Due to the weird Makefile setup of sched the various files do not
compile as stand alone units. The new generation of editors are trying
to do just this -- mostly to offer fancy things like completions but
also better syntax highlighting and code navigation.
Specifically, I've been playing around with neovim and clangd.
Setting up clangd on the kernel source is a giant pain in the arse
(this really should be improved), but once you do manage, you run into
dumb stuff like the above.
Fix up the scheduler files to at least pretend to work.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20250523164348.GN39944@noisy.programming.kicks-ass.net
scx_locked_rq() is used both from ext.c and ext_idle.c, move it to ext.h
as a static inline function.
No functional changes.
v2: Rename locked_rq to scx_locked_rq_state, expose it and make
scx_locked_rq() inline, as suggested by Tejun.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_rq_bypassing() is used both from ext.c and ext_idle.c, move it to
ext.h as a static inline function.
No functional changes.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Functions that are only used within ext_idle.c can be marked as static
to limit their scope.
No functional changes.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There's no need to make scx_bpf_cpu_node() dependent on CONFIG_NUMA,
since cpu_to_node() can be used also in systems with CONFIG_NUMA
disabled.
This also allows to always validate the @cpu argument regardless of the
CONFIG_NUMA settings.
Fixes: 01059219b0 ("sched_ext: idle: Introduce node-aware idle cpu kfunc helpers")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move this API to the canonical timer_*() namespace.
[ tglx: Redone against pre rc1 ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com
Two fixes in the built-in idle selection helpers.
- Fix prev_cpu handling to guarantee that idle selection never returns a CPU
that's not allowed.
- Skip cross-node search when !NUMA which could lead to infinite looping due
to a bug in NUMA iterator.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCaECWBw4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGfV9AP4mk63TUsLdqwa6iqE0dZArOAhj8QXETsv1Q0+y
FGQKEQEAxPNJx3ifhzgXoQi1SOZkqeq44erbcy0x7owtb+QBVgs=
=G1uN
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"Two fixes in the built-in idle selection helpers:
- Fix prev_cpu handling to guarantee that idle selection never
returns a CPU that's not allowed
- Skip cross-node search when !NUMA which could lead to infinite
looping due to a bug in NUMA iterator"
* tag 'sched_ext-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: idle: Skip cross-node search with !CONFIG_NUMA
sched_ext: idle: Properly handle invalid prev_cpu during idle selection
In the idle CPU selection logic, attempting cross-node searches adds
unnecessary complexity when CONFIG_NUMA is disabled.
Since there's no meaningful concept of nodes in this case, simplify the
logic by restricting the idle CPU search to the current node only.
Fixes: 48849271e6 ("sched_ext: idle: Per-node idle cpumasks")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Sergey Senozhatsky adds infrastructure for passing algorithm-specific
parameters into zram. A single parameter `winbits' is implemented at
this time.
- The 5 patch series "memcg: nmi-safe kmem charging" from Shakeel Butt
makes memcg charging nmi-safe, which is required by BFP, which can
operate in NMI context.
- The 5 patch series "Some random fixes and cleanup to shmem" from
Kemeng Shi implements small fixes and cleanups in the shmem code.
- The 2 patch series "Skip mm selftests instead when kernel features are
not present" from Zi Yan fixes some issues in the MM selftest code.
- The 2 patch series "mm/damon: build-enable essential DAMON components
by default" from SeongJae Park reworks DAMON Kconfig to make it easier
to enable CONFIG_DAMON.
- The 2 patch series "sched/numa: add statistics of numa balance task
migration" from Libo Chen adds more info into sysfs and procfs files to
improve visibility into the NUMA balancer's task migration activity.
- The 4 patch series "selftests/mm: cow and gup_longterm cleanups" from
Mark Brown provides various updates to some of the MM selftests to make
them play better with the overall containing framework.
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCaDzA9wAKCRDdBJ7gKXxA
js8sAP9V3COg+vzTmimzP3ocTkkbbIJzDfM6nXpE2EQ4BR3ejwD+NsIT2ZLtTF6O
LqAZpgO7ju6wMjR/lM30ebCq5qFbZAw=
=oruw
-----END PGP SIGNATURE-----
Merge tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull more MM updates from Andrew Morton:
- "zram: support algorithm-specific parameters" from Sergey Senozhatsky
adds infrastructure for passing algorithm-specific parameters into
zram. A single parameter `winbits' is implemented at this time.
- "memcg: nmi-safe kmem charging" from Shakeel Butt makes memcg
charging nmi-safe, which is required by BFP, which can operate in NMI
context.
- "Some random fixes and cleanup to shmem" from Kemeng Shi implements
small fixes and cleanups in the shmem code.
- "Skip mm selftests instead when kernel features are not present" from
Zi Yan fixes some issues in the MM selftest code.
- "mm/damon: build-enable essential DAMON components by default" from
SeongJae Park reworks DAMON Kconfig to make it easier to enable
CONFIG_DAMON.
- "sched/numa: add statistics of numa balance task migration" from Libo
Chen adds more info into sysfs and procfs files to improve visibility
into the NUMA balancer's task migration activity.
- "selftests/mm: cow and gup_longterm cleanups" from Mark Brown
provides various updates to some of the MM selftests to make them
play better with the overall containing framework.
* tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (43 commits)
mm/khugepaged: clean up refcount check using folio_expected_ref_count()
selftests/mm: fix test result reporting in gup_longterm
selftests/mm: report unique test names for each cow test
selftests/mm: add helper for logging test start and results
selftests/mm: use standard ksft_finished() in cow and gup_longterm
selftests/damon/_damon_sysfs: skip testcases if CONFIG_DAMON_SYSFS is disabled
sched/numa: add statistics of numa balance task
sched/numa: fix task swap by skipping kernel threads
tools/testing: check correct variable in open_procmap()
tools/testing/vma: add missing function stub
mm/gup: update comment explaining why gup_fast() disables IRQs
selftests/mm: two fixes for the pfnmap test
mm/khugepaged: fix race with folio split/free using temporary reference
mm: add CONFIG_PAGE_BLOCK_ORDER to select page block order
mmu_notifiers: remove leftover stub macros
selftests/mm: deduplicate test names in madv_populate
kcov: rust: add flags for KCOV with Rust
mm: rust: make CONFIG_MMU ifdefs more narrow
mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables()
mm/damon/Kconfig: enable CONFIG_DAMON by default
...
On systems with NUMA balancing enabled, it has been found that tracking
task activities resulting from NUMA balancing is beneficial. NUMA
balancing employs two mechanisms for task migration: one is to migrate
a task to an idle CPU within its preferred node, and the other is to
swap tasks located on different nodes when they are on each other's
preferred nodes.
The kernel already provides NUMA page migration statistics in
/sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched. However, it
lacks statistics regarding task migration and swapping. Therefore,
relevant counts for task migration and swapping should be added.
The following two new fields:
numa_task_migrated
numa_task_swapped
will be shown in /sys/fs/cgroup/{GROUP}/memory.stat, /proc/{PID}/sched
and /proc/vmstat.
Introducing both per-task and per-memory cgroup (memcg) NUMA balancing
statistics facilitates a rapid evaluation of the performance and
resource utilization of the target workload. For instance, users can
first identify the container with high NUMA balancing activity and then
further pinpoint a specific task within that group, and subsequently
adjust the memory policy for that task. In short, although it is
possible to iterate through /proc/$pid/sched to locate the problematic
task, the introduction of aggregated NUMA balancing activity for tasks
within each memcg can assist users in identifying the task more
efficiently through a divide-and-conquer approach.
As Libo Chen pointed out, the memcg event relies on the text names in
vmstat_text, and /proc/vmstat generates corresponding items based on
vmstat_text. Thus, the relevant task migration and swapping events
introduced in vmstat_text also need to be populated by
count_vm_numa_event(), otherwise these values are zero in /proc/vmstat.
In theory, task migration and swap events are part of the scheduler's
activities. The reason for exposing them through the
memory.stat/vmstat interface is that we already have NUMA balancing
statistics in memory.stat/vmstat, and these events are closely related
to each other. Following Shakeel's suggestion, we describe the
end-to-end flow/story of all these events occurring on a timeline for
future reference:
The goal of NUMA balancing is to co-locate a task and its memory pages
on the same NUMA node. There are two strategies: migrate the pages to
the task's node, or migrate the task to the node where its pages
reside.
Suppose a task p1 is running on Node 0, but its pages are located on
Node 1. NUMA page fault statistics for p1 reveal its "page footprint"
across nodes. If NUMA balancing detects that most of p1's pages are on
Node 1:
1.Page Migration Attempt:
The Numa balance first tries to migrate p1's pages to Node 0.
The numa_page_migrate counter increments.
2.Task Migration Strategies:
After the page migration finishes, Numa balance checks every
1 second to see if p1 can be migrated to Node 1.
Case 2.1: Idle CPU Available
If Node 1 has an idle CPU, p1 is directly scheduled there. This
event is logged as numa_task_migrated.
Case 2.2: No Idle CPU (Task Swap)
If all CPUs on Node1 are busy, direct migration could cause CPU
contention or load imbalance. Instead: The Numa balance selects a
candidate task p2 on Node 1 that prefers Node 0 (e.g., due to its own
page footprint). p1 and p2 are swapped. This cross-node swap is
recorded as numa_task_swapped.
Link: https://lkml.kernel.org/r/d00edb12ba0f0de3c5222f61487e65f2ac58f5b1.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/7ef90a88602ed536be46eba7152ed0d33bad5790.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Ayush Jain <Ayush.jain3@amd.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Libo Chen <libo.chen@oracle.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "sched/numa: add statistics of numa balance task migration",
v6.
Introduce task migration and swap statistics in the following places:
/sys/fs/cgroup/{GROUP}/memory.stat
/proc/{PID}/sched
/proc/vmstat
These statistics facilitate a rapid evaluation of the performance and
resource utilization of the target workload.
This patch (of 2):
Task swapping is triggered when there are no idle CPUs in task A's
preferred node. In this case, the NUMA load balancer chooses a task B
on A's preferred node and swaps B with A. This helps improve NUMA
locality without introducing load imbalance between nodes. In the
current implementation, B's NUMA node preference is not mandatory.
That is to say, a kernel thread might be incorrectly chosen as B.
However, kernel thread and user space thread that does not have mm are
not supposed to be covered by NUMA balancing because NUMA balancing
only considers user pages via VMAs.
According to Peter's suggestion for fixing this issue, we use
PF_KTHREAD to skip the kernel thread. curr->mm is also checked because
it is possible that user_mode_thread() might create a user thread
without an mm. As per Prateek's analysis, after adding the PF_KTHREAD
check, there is no need to further check the PF_IDLE flag:
: - play_idle_precise() already ensures PF_KTHREAD is set before adding
: PF_IDLE
:
: - cpu_startup_entry() is only called from the startup thread which
: should be marked with PF_KTHREAD (based on my understanding looking at
: commit cff9b2332a ("kernel/sched: Modify initial boot task idle
: setup"))
In summary, the check in task_numa_compare() now aligns with
task_tick_numa().
Link: https://lkml.kernel.org/r/cover.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/43d68b356b25d124f0d222ebedf3859e86eefb9f.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/cover.1748002400.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/eaacc9c9bd37bac92d43a671867d85b2fdad3b06.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Libo Chen <libo.chen@oracle.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Tested-by: Ayush Jain <Ayush.jain3@amd.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
simplifies the act of creating a pte which addresses the first page in a
folio and reduces the amount of plumbing which architecture must
implement to provide this.
- The 8 patch series "Misc folio patches for 6.16" from Matthew Wilcox
is a shower of largely unrelated folio infrastructure changes which
clean things up and better prepare us for future work.
- The 3 patch series "memory,x86,acpi: hotplug memory alignment
advisement" from Gregory Price adds early-init code to prevent x86 from
leaving physical memory unused when physical address regions are not
aligned to memory block size.
- The 2 patch series "mm/compaction: allow more aggressive proactive
compaction" from Michal Clapinski provides some tuning of the (sadly,
hard-coded (more sadly, not auto-tuned)) thresholds for our invokation
of proactive compaction. In a simple test case, the reduction of a guest
VM's memory consumption was dramatic.
- The 8 patch series "Minor cleanups and improvements to swap freeing
code" from Kemeng Shi provides some code cleaups and a small efficiency
improvement to this part of our swap handling code.
- The 6 patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API"
from Dmitry Levin adds the ability for a ptracer to modify syscalls
arguments. At this time we can alter only "system call information that
are used by strace system call tampering, namely, syscall number,
syscall arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- The 3 patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report
guard regions" from Andrei Vagin extends the info returned by the
PAGEMAP_SCAN ioctl against /proc/pid/pagemap. This permits CRIU to more
efficiently get at the info about guard regions.
- The 2 patch series "Fix parameter passed to page_mapcount_is_type()"
from Gavin Shan implements that fix. No runtime effect is expected
because validate_page_before_insert() happens to fix up this error.
- The 3 patch series "kernel/events/uprobes: uprobe_write_opcode()
rewrite" from David Hildenbrand basically brings uprobe text poking into
the current decade. Remove a bunch of hand-rolled implementation in
favor of using more current facilities.
- The 3 patch series "mm/ptdump: Drop assumption that pxd_val() is u64"
from Anshuman Khandual provides enhancements and generalizations to the
pte dumping code. This might be needed when 128-bit Page Table
Descriptors are enabled for ARM.
- The 12 patch series "Always call constructor for kernel page tables"
from Kevin Brodsky "ensures that the ctor/dtor is always called for
kernel pgtables, as it already is for user pgtables". This permits the
addition of more functionality such as "insert hooks to protect page
tables". This change does result in various architectures performing
unnecesary work, but this is fixed up where it is anticipated to occur.
- The 9 patch series "Rust support for mm_struct, vm_area_struct, and
mmap" from Alice Ryhl adds plumbing to permit Rust access to core MM
structures.
- The 3 patch series "fix incorrectly disallowed anonymous VMA merges"
from Lorenzo Stoakes takes advantage of some VMA merging opportunities
which we've been missing for 15 years.
- The 4 patch series "mm/madvise: batch tlb flushes for MADV_DONTNEED
and MADV_FREE" from SeongJae Park optimizes process_madvise()'s TLB
flushing. Instead of flushing each address range in the provided iovec,
we batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- The 6 patch series "Track node vacancy to reduce worst case allocation
counts" from Sidhartha Kumar makes the maple tree smarter about its node
preallocation. stress-ng mmap performance increased by single-digit
percentages and the amount of unnecessarily preallocated memory was
dramaticelly reduced.
- The 3 patch series "mm/gup: Minor fix, cleanup and improvements" from
Baoquan He removes a few unnecessary things which Baoquan noted when
reading the code.
- The 3 patch series ""Enhance sysfs handling for memory hotplug in
weighted interleave" from Rakie Kim "enhances the weighted interleave
policy in the memory management subsystem by improving sysfs handling,
fixing memory leaks, and introducing dynamic sysfs updates for memory
hotplug support". Fixes things on error paths which we are unlikely to
hit.
- The 7 patch series "mm/damon: auto-tune DAMOS for NUMA setups
including tiered memory" from SeongJae Park introduces new DAMOS quota
goal metrics which eliminate the manual tuning which is required when
utilizing DAMON for memory tiering.
- The 5 patch series "mm/vmalloc.c: code cleanup and improvements" from
Baoquan He provides cleanups and small efficiency improvements which
Baoquan found via code inspection.
- The 2 patch series "vmscan: enforce mems_effective during demotion"
from Gregory Price "changes reclaim to respect cpuset.mems_effective
during demotion when possible". because "presently, reclaim explicitly
ignores cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated." "This is useful for isolating workloads on a
multi-tenant system from certain classes of memory more consistently."
- The 2 patch series ""Clean up split_huge_pmd_locked() and remove
unnecessary folio pointers" from Gavin Guo provides minor cleanups and
efficiency gains in in the huge page splitting and migrating code.
- The 3 patch series "Use kmem_cache for memcg alloc" from Huan Yang
creates a slab cache for `struct mem_cgroup', yielding improved memory
utilization.
- The 4 patch series "add max arg to swappiness in memory.reclaim and
lru_gen" from Zhongkun He adds a new "max" argument to the "swappiness="
argument for memory.reclaim MGLRU's lru_gen. This directs proactive
reclaim to reclaim from only anon folios rather than file-backed folios.
- The 17 patch series "kexec: introduce Kexec HandOver (KHO)" from Mike
Rapoport is the first step on the path to permitting the kernel to
maintain existing VMs while replacing the host kernel via file-based
kexec. At this time only memblock's reserve_mem is preserved.
- The 7 patch series "mm: Introduce for_each_valid_pfn()" from David
Woodhouse provides and uses a smarter way of looping over a pfn range.
By skipping ranges of invalid pfns.
- The 2 patch series "sched/numa: Skip VMA scanning on memory pinned to
one NUMA node via cpuset.mems" from Libo Chen removes a lot of pointless
VMA scanning when a task is pinned a single NUMA mode. Dramatic
performance benefits were seen in some real world cases.
- The 2 patch series "JFS: Implement migrate_folio for
jfs_metapage_aops" from Shivank Garg addresses a warning which occurs
during memory compaction when using JFS.
- The 4 patch series "move all VMA allocation, freeing and duplication
logic to mm" from Lorenzo Stoakes moves some VMA code from kernel/fork.c
into the more appropriate mm/vma.c.
- The 6 patch series "mm, swap: clean up swap cache mapping helper" from
Kairui Song provides code consolidation and cleanups related to the
folio_index() function.
- The 2 patch series "mm/gup: Cleanup memfd_pin_folios()" from Vishal
Moola does that.
- The 8 patch series "memcg: Fix test_memcg_min/low test failures" from
Waiman Long addresses some bogus failures which are being reported by
the test_memcontrol selftest.
- The 3 patch series "eliminate mmap() retry merge, add .mmap_prepare
hook" from Lorenzo Stoakes commences the deprecation of
file_operations.mmap() in favor of the new
file_operations.mmap_prepare(). The latter is more restrictive and
prevents drivers from messing with things in ways which, amongst other
problems, may defeat VMA merging.
- The 4 patch series "memcg: decouple memcg and objcg stocks"" from
Shakeel Butt decouples the per-cpu memcg charge cache from the objcg's
one. This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- The 6 patch series "mm/damon: minor fixups and improvements for code,
tests, and documents" from SeongJae Park is "yet another batch of
miscellaneous DAMON changes. Fix and improve minor problems in code,
tests and documents."
- The 7 patch series "memcg: make memcg stats irq safe" from Shakeel
Butt converts memcg stats to be irq safe. Another step along the way to
making memcg charging and stats updates NMI-safe, a BPF requirement.
- The 4 patch series "Let unmap_hugepage_range() and several related
functions take folio instead of page" from Fan Ni provides folio
conversions in the hugetlb code.
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCaDt5qgAKCRDdBJ7gKXxA
ju6XAP9nTiSfRz8Cz1n5LJZpFKEGzLpSihCYyR6P3o1L9oe3mwEAlZ5+XAwk2I5x
Qqb/UGMEpilyre1PayQqOnct3aSL9Ao=
=tYYm
-----END PGP SIGNATURE-----
Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.
- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.
- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.
- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.
- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.
- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.
- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.
- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.
- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.
- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.
This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.
- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.
- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.
- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.
Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.
stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.
- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.
- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.
- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.
- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.
- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.
This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.
- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.
- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.
- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.
This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.
- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.
- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.
- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.
Dramatic performance benefits were seen in some real world cases.
- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.
- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.
- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.
- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.
- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.
- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().
The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.
- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.
This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.
- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.
- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.
* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...
The default idle selection policy doesn't properly handle the case where
@prev_cpu is not part of the task's allowed CPUs.
In this situation, it may return an idle CPU that is not usable by the
task, breaking the assumption that the returned CPU must always be
within the allowed cpumask, causing inefficiencies or even stalls in
certain cases.
This issue can arise in the following cases:
- The task's affinity may have changed by the time the function is
invoked, especially now that the idle selection logic can be used
from multiple contexts (i.e., BPF test_run call).
- The BPF scheduler may provide a @prev_cpu that is not part of the
allowed mask, either unintentionally or as a placement hint. In fact
@prev_cpu may not necessarily refer to the CPU the task last ran on,
but it can also be considered as a target CPU that the scheduler
wishes to use for the task.
Therefore, enforce the right behavior by always checking whether
@prev_cpu is in the allowed mask, when using scx_bpf_select_cpu_and(),
and it's also usable by the task (@p->cpus_ptr). If it is not, try to
find a valid CPU nearby @prev_cpu, following the usual locality-aware
fallback path (SMT, LLC, node, allowed CPUs).
This ensures the returned CPU is always allowed, improving robustness to
affinity changes and invalid scheduler hints, while preserving locality
as much as possible.
Fixes: a730e3f7a4 ("sched_ext: idle: Consolidate default idle CPU selection kfuncs")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
-----BEGIN PGP SIGNATURE-----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=j3t8
-----END PGP SIGNATURE-----
Merge tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Fix and improve BTF deduplication of identical BTF types (Alan
Maguire and Andrii Nakryiko)
- Support up to 12 arguments in BPF trampoline on arm64 (Xu Kuohai and
Alexis Lothoré)
- Support load-acquire and store-release instructions in BPF JIT on
riscv64 (Andrea Parri)
- Fix uninitialized values in BPF_{CORE,PROBE}_READ macros (Anton
Protopopov)
- Streamline allowed helpers across program types (Feng Yang)
- Support atomic update for hashtab of BPF maps (Hou Tao)
- Implement json output for BPF helpers (Ihor Solodrai)
- Several s390 JIT fixes (Ilya Leoshkevich)
- Various sockmap fixes (Jiayuan Chen)
- Support mmap of vmlinux BTF data (Lorenz Bauer)
- Support BPF rbtree traversal and list peeking (Martin KaFai Lau)
- Tests for sockmap/sockhash redirection (Michal Luczaj)
- Introduce kfuncs for memory reads into dynptrs (Mykyta Yatsenko)
- Add support for dma-buf iterators in BPF (T.J. Mercier)
- The verifier support for __bpf_trap() (Yonghong Song)
* tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (135 commits)
bpf, arm64: Remove unused-but-set function and variable.
selftests/bpf: Add tests with stack ptr register in conditional jmp
bpf: Do not include stack ptr register in precision backtracking bookkeeping
selftests/bpf: enable many-args tests for arm64
bpf, arm64: Support up to 12 function arguments
bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()
bpf: Avoid __bpf_prog_ret0_warn when jit fails
bpftool: Add support for custom BTF path in prog load/loadall
selftests/bpf: Add unit tests with __bpf_trap() kfunc
bpf: Warn with __bpf_trap() kfunc maybe due to uninitialized variable
bpf: Remove special_kfunc_set from verifier
selftests/bpf: Add test for open coded dmabuf_iter
selftests/bpf: Add test for dmabuf_iter
bpf: Add open coded dmabuf iterator
bpf: Add dmabuf iterator
dma-buf: Rename debugfs symbols
bpf: Fix error return value in bpf_copy_from_user_dynptr
libbpf: Use mmap to parse vmlinux BTF from sysfs
selftests: bpf: Add a test for mmapable vmlinux BTF
btf: Allow mmap of vmlinux btf
...
- More in-kernel idle CPU selection improvements. Expand topology awareness
coverage add scx_bpf_select_cpu_and() to allow more flexibility. The idle
CPU selection kfuncs can now be called from unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable change is
replacing some static_key tests with dynamic tests as the test results may
differ depending on the scheduler instance. This isn't expected to cause
meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into for-6.16
to resolve the conflicts.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCaDYZMw4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGfbcAQDRloVb/d5RfC6VYlue9EV1jHuoJefTYHvR3jmO
ju70EQEAjLBXw58XAePQ9La/570JELgsC5FzJp3tLTilGx2JyQA=
=7cDG
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- More in-kernel idle CPU selection improvements. Expand topology
awareness coverage add scx_bpf_select_cpu_and() to allow more
flexibility. The idle CPU selection kfuncs can now be called from
unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable
change is replacing some static_key tests with dynamic tests as the
test results may differ depending on the scheduler instance. This
isn't expected to cause meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into
for-6.16 to resolve the conflicts.
* tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (49 commits)
sched_ext: Call ops.update_idle() after updating builtin idle bits
sched_ext, docs: convert mentions of "CFS" to "fair-class scheduler"
selftests/sched_ext: Update test enq_select_cpu_fails
sched_ext: idle: Consolidate default idle CPU selection kfuncs
selftests/sched_ext: Add test for scx_bpf_select_cpu_and() via test_run
sched_ext: idle: Allow scx_bpf_select_cpu_and() from unlocked context
sched_ext: idle: Validate locking correctness in scx_bpf_select_cpu_and()
sched_ext: Make scx_kf_allowed_if_unlocked() available outside ext.c
sched_ext, docs: add label
sched_ext: Explain the temporary situation around scx_root dereferences
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Cleanup [__]scx_exit/error*()
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Clean up scx_root usages
Documentation: scheduler: Changed lowercase acronyms to uppercase
sched_ext: Avoid NULL scx_root deref in __scx_exit()
sched_ext: Add RCU protection to scx_root in DSQ iterator
sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()
sched_ext: Move disable machinery into scx_sched
sched_ext: Move event_stats_cpu into scx_sched
...
- Fix potential division-by-zero error in em_compute_costs() (Yaxiong
Tian).
- Fix typos in energy model documentation and example driver code (Moon
Hee Lee, Atul Kumar Pant).
- Rearrange the energy model management code and add a new function for
adjusting a CPU energy model after adjusting the capacity of the
given CPU to it (Rafael Wysocki).
- Refactor cpufreq_online(), add and use cpufreq policy locking guards,
use __free() in policy reference counting, and clean up core cpufreq
code on top of that (Rafael Wysocki).
- Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
Kumar).
- Fix des_perf clamping with max_perf in amd_pstate_update() (Dhananjay
Ugwekar).
- Add offline, online and suspend callbacks to the amd-pstate driver,
rename and use the existing amd_pstate_epp callbacks in it (Dhananjay
Ugwekar).
- Add support for the "Requested CPU Min frequency" BIOS option to the
amd-pstate driver (Dhananjay Ugwekar).
- Reset amd-pstate driver mode after running selftests (Swapnil
Sapkal).
- Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
Chancellor).
- Add helper for governor checks to the schedutil cpufreq governor and
move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki).
- Populate the cpu_capacity sysfs entries from the intel_pstate driver
after registering asym capacity support (Ricardo Neri).
- Add support for enabling Energy-aware scheduling (EAS) to the
intel_pstate driver when operating in the passive mode on a hybrid
platform (Rafael Wysocki).
- Drop redundant cpus_read_lock() from store_local_boost() in the
cpufreq core (Seyediman Seyedarab).
- Replace sscanf() with kstrtouint() in the cpufreq code and use a
symbol instead of a raw number in it (Bowen Yu).
- Add support for autonomous CPU performance state selection to the
CPPC cpufreq driver (Lifeng Zheng).
- OPP: Add dev_pm_opp_set_level() (Praveen Talari).
- Introduce scope-based cleanup headers and mutex locking guards in OPP
core (Viresh Kumar).
- Switch OPP to use kmemdup_array() (Zhang Enpei).
- Optimize bucket assignment when next_timer_ns equals KTIME_MAX in the
menu cpuidle governor (Zhongqiu Han).
- Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla).
- Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
Bityutskiy).
- Fix typos in two comments in the teo cpuidle governor (Atul Kumar
Pant).
- Fix denying of auto suspend in pm_suspend_timer_fn() (Charan Teja
Kalla).
- Move debug runtime PM attributes to runtime_attrs[] (Rafael Wysocki).
- Add new devm_ functions for enabling runtime PM and runtime PM
reference counting (Bence Csókás).
- Remove size arguments from strscpy() calls in the hibernation core
code (Thorsten Blum).
- Adjust the handling of devices with asynchronous suspend enabled
during system suspend and resume to start resuming them immediately
after resuming their parents and to start suspending such a device
immediately after suspending its first child (Rafael Wysocki).
- Adjust messages printed during tasks freezing to avoid using
pr_cont() (Andrew Sayers, Paul Menzel).
- Clean up unnecessary usage of !! in pm_print_times_init() (Zihuan
Zhang).
- Add missing wakeup source attribute relax_count to sysfs and
remove the space character at the end ofi the string produced by
pm_show_wakelocks() (Zijun Hu).
- Add configurable pm_test delay for hibernation (Zihuan Zhang).
- Disable asynchronous suspend in ucsi_ccg_probe() to prevent the
cypd4226 device on Tegra boards from suspending prematurely (Jon
Hunter).
- Unbreak printing PM debug messages during hibernation and clean up
some related code (Rafael Wysocki).
- Add a systemd service to run cpupower and change cpupower binding's
Makefile to use -lcpupower (John B. Wyatt IV, Francesco Poli).
-----BEGIN PGP SIGNATURE-----
iQFGBAABCAAwFiEEcM8Aw/RY0dgsiRUR7l+9nS/U47UFAmg0xS0SHHJqd0Byand5
c29ja2kubmV0AAoJEO5fvZ0v1OO1AwwH/Rvgza5YBPb9JZqWJT/ZiBw7HcEWHhP1
fNfcVU1gXPZiF0yoPfjfJua6BcLj6lyQ3d/+zWqqAcWfmRSD6HPe8yYz8qALUAqj
RWhDa04aGj6B9bQuOjejatznYlQlkwCRT7zec+75D+dAHVMqR/Vt2LFAetCadgHe
MQibAQmVFXu3RFkBjReTAdGzVoTXkwoZDrzdfA2aFAfMJNtJpOW4atUZvnucuctv
VK3ZratrctCIw7yXEoB1nWSmlY7R5JlslplBfndjmmOnky3YxNr7C6paqwtbTWoF
MiX48qkmLOGeO6gS8s/lVCDQ4oZ+UNFQvXRsM5NGjycBikhHX/dp/w4=
=dIqJ
-----END PGP SIGNATURE-----
Merge tag 'pm-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Once again, the changes are dominated by cpufreq updates, but this
time the majority of them are cpufreq core changes, mostly related to
the introduction of policy locking guards and __free() usage, and
fixes related to boost handling.
Still, there is also a significant update of the intel_pstate driver
making it register an energy model when running on a hybrid platform
which is used for enabling energy-aware scheduling (EAS) if the driver
operates in the passive mode (and schedutil is used as the cpufreq
governor for all CPUs which is the passive mode default).
There are some amd-pstate driver updates too, for a good measure,
including the "Requested CPU Min frequency" BIOS option support and
new online/offline callbacks.
In the cpuidle space, the most significant change is the addition of a
C1 demotion on/off sysfs knob to intel_idle which should help some
users to configure their systems more precisely. There is also the
conversion of the PSCI cpuidle driver to a faux device one and there
are two small updates of cpuidle governors.
Device power management is also modified quite a bit, especially the
handling of devices with asynchronous suspend and resume enabled
during system transitions. They are now going to be handled more
asynchronously during suspend transitions and somewhat less
aggressively during resume transitions.
Apart from the above, the operating performance points (OPP) library
is now going to use mutex locking guards and scope-based cleanup
helpers and there is the usual bunch of assorted fixes and code
cleanups.
Specifics:
- Fix potential division-by-zero error in em_compute_costs() (Yaxiong
Tian)
- Fix typos in energy model documentation and example driver code
(Moon Hee Lee, Atul Kumar Pant)
- Rearrange the energy model management code and add a new function
for adjusting a CPU energy model after adjusting the capacity of
the given CPU to it (Rafael Wysocki)
- Refactor cpufreq_online(), add and use cpufreq policy locking
guards, use __free() in policy reference counting, and clean up
core cpufreq code on top of that (Rafael Wysocki)
- Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
Kumar)
- Fix des_perf clamping with max_perf in amd_pstate_update()
(Dhananjay Ugwekar)
- Add offline, online and suspend callbacks to the amd-pstate driver,
rename and use the existing amd_pstate_epp callbacks in it
(Dhananjay Ugwekar)
- Add support for the "Requested CPU Min frequency" BIOS option to
the amd-pstate driver (Dhananjay Ugwekar)
- Reset amd-pstate driver mode after running selftests (Swapnil
Sapkal)
- Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
Chancellor)
- Add helper for governor checks to the schedutil cpufreq governor
and move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki)
- Populate the cpu_capacity sysfs entries from the intel_pstate
driver after registering asym capacity support (Ricardo Neri)
- Add support for enabling Energy-aware scheduling (EAS) to the
intel_pstate driver when operating in the passive mode on a hybrid
platform (Rafael Wysocki)
- Drop redundant cpus_read_lock() from store_local_boost() in the
cpufreq core (Seyediman Seyedarab)
- Replace sscanf() with kstrtouint() in the cpufreq code and use a
symbol instead of a raw number in it (Bowen Yu)
- Add support for autonomous CPU performance state selection to the
CPPC cpufreq driver (Lifeng Zheng)
- OPP: Add dev_pm_opp_set_level() (Praveen Talari)
- Introduce scope-based cleanup headers and mutex locking guards in
OPP core (Viresh Kumar)
- Switch OPP to use kmemdup_array() (Zhang Enpei)
- Optimize bucket assignment when next_timer_ns equals KTIME_MAX in
the menu cpuidle governor (Zhongqiu Han)
- Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla)
- Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
Bityutskiy)
- Fix typos in two comments in the teo cpuidle governor (Atul Kumar
Pant)
- Fix denying of auto suspend in pm_suspend_timer_fn() (Charan Teja
Kalla)
- Move debug runtime PM attributes to runtime_attrs[] (Rafael
Wysocki)
- Add new devm_ functions for enabling runtime PM and runtime PM
reference counting (Bence Csókás)
- Remove size arguments from strscpy() calls in the hibernation core
code (Thorsten Blum)
- Adjust the handling of devices with asynchronous suspend enabled
during system suspend and resume to start resuming them immediately
after resuming their parents and to start suspending such a device
immediately after suspending its first child (Rafael Wysocki)
- Adjust messages printed during tasks freezing to avoid using
pr_cont() (Andrew Sayers, Paul Menzel)
- Clean up unnecessary usage of !! in pm_print_times_init() (Zihuan
Zhang)
- Add missing wakeup source attribute relax_count to sysfs and remove
the space character at the end ofi the string produced by
pm_show_wakelocks() (Zijun Hu)
- Add configurable pm_test delay for hibernation (Zihuan Zhang)
- Disable asynchronous suspend in ucsi_ccg_probe() to prevent the
cypd4226 device on Tegra boards from suspending prematurely (Jon
Hunter)
- Unbreak printing PM debug messages during hibernation and clean up
some related code (Rafael Wysocki)
- Add a systemd service to run cpupower and change cpupower binding's
Makefile to use -lcpupower (John B. Wyatt IV, Francesco Poli)"
* tag 'pm-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (72 commits)
cpufreq: CPPC: Add support for autonomous selection
cpufreq: Update sscanf() to kstrtouint()
cpufreq: Replace magic number
OPP: switch to use kmemdup_array()
PM: freezer: Rewrite restarting tasks log to remove stray *done.*
PM: runtime: fix denying of auto suspend in pm_suspend_timer_fn()
cpufreq: drop redundant cpus_read_lock() from store_local_boost()
cpupower: do not install files to /etc/default/
cpupower: do not call systemctl at install time
cpupower: do not write DESTDIR to cpupower.service
PM: sleep: Introduce pm_sleep_transition_in_progress()
cpufreq/amd-pstate: Avoid shadowing ret in amd_pstate_ut_check_driver()
cpufreq: intel_pstate: Document hybrid processor support
cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache
cpufreq: intel_pstate: EAS support for hybrid platforms
PM: EM: Introduce em_adjust_cpu_capacity()
PM: EM: Move CPU capacity check to em_adjust_new_capacity()
PM: EM: Documentation: Fix typos in example driver code
cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()
PM: sleep: Introduce pm_suspend_in_progress()
...
Merge cpufreq updates for 6.16-rc1:
- Refactor cpufreq_online(), add and use cpufreq policy locking guards,
use __free() in policy reference counting, and clean up core cpufreq
code on top of that (Rafael Wysocki).
- Fix boost handling on CPU suspend/resume and sysfs updates (Viresh
Kumar).
- Fix des_perf clamping with max_perf in amd_pstate_update() (Dhananjay
Ugwekar).
- Add offline, online and suspend callbacks to the amd-pstate driver,
rename and use the existing amd_pstate_epp callbacks in it (Dhananjay
Ugwekar).
- Add support for the "Requested CPU Min frequency" BIOS option to the
amd-pstate driver (Dhananjay Ugwekar).
- Reset amd-pstate driver mode after running selftests (Swapnil
Sapkal).
- Add helper for governor checks to the schedutil cpufreq governor and
move cpufreq-specific EAS checks to cpufreq (Rafael Wysocki).
- Populate the cpu_capacity sysfs entries from the intel_pstate driver
after registering asym capacity support (Ricardo Neri).
- Add support for enabling Energy-aware scheduling (EAS) to the
intel_pstate driver when operating in the passive mode on a hybrid
platform (Rafael Wysocki).
- Avoid shadowing ret in amd_pstate_ut_check_driver() (Nathan
Chancellor).
- Drop redundant cpus_read_lock() from store_local_boost() in the
cpufreq core (Seyediman Seyedarab).
- Replace sscanf() with kstrtouint() in the cpufreq code and use a
symbol instead of a raw number in it (Bowen Yu).
- Add support for autonomous CPU performance state selection to the
CPPC cpufreq driver (Lifeng Zheng).
* pm-cpufreq: (31 commits)
cpufreq: CPPC: Add support for autonomous selection
cpufreq: Update sscanf() to kstrtouint()
cpufreq: Replace magic number
cpufreq: drop redundant cpus_read_lock() from store_local_boost()
cpufreq/amd-pstate: Avoid shadowing ret in amd_pstate_ut_check_driver()
cpufreq: intel_pstate: Document hybrid processor support
cpufreq: intel_pstate: EAS: Increase cost for CPUs using L3 cache
cpufreq: intel_pstate: EAS support for hybrid platforms
cpufreq: Drop policy locking from cpufreq_policy_is_good_for_eas()
cpufreq: intel_pstate: Populate the cpu_capacity sysfs entries
arch_topology: Relocate cpu_scale to topology.[h|c]
cpufreq/sched: Move cpufreq-specific EAS checks to cpufreq
cpufreq/sched: schedutil: Add helper for governor checks
amd-pstate-ut: Reset amd-pstate driver mode after running selftests
cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option
cpufreq/amd-pstate: Add offline, online and suspend callbacks for amd_pstate_driver
cpufreq: Force sync policy boost with global boost on sysfs update
cpufreq: Preserve policy's boost state after resume
cpufreq: Introduce policy_set_boost()
cpufreq: Don't unnecessarily call set_boost()
...
BPF schedulers that use both builtin CPU idle mechanism and
ops.update_idle() may want to use the latter to create interlocking between
ops.enqueue() and CPU idle transitions so that either ops.enqueue() sees the
idle bit or ops.update_idle() sees the task queued somewhere. This can
prevent race conditions where CPUs go idle while tasks are waiting in DSQs.
For such interlocking to work, ops.update_idle() must be called after
builtin CPU masks are updated. Relocate the invocation. Currently, there are
no ordering requirements on transitions from idle and this relocation isn't
expected to make meaningful differences in that direction.
This also makes the ops.update_idle() behavior semantically consistent:
any action performed in this callback should be able to override the
builtin idle state, not the other way around.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-and-tested-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
There is no reason to restrict scx_bpf_select_cpu_dfl() invocations to
ops.select_cpu() while allowing scx_bpf_select_cpu_and() to be used from
multiple contexts, as both provide equivalent functionality, with the
latter simply accepting an additional "allowed" cpumask.
Therefore, unify the two APIs, enabling both kfuncs to be used from
ops.select_cpu(), ops.enqueue(), and unlocked contexts (e.g., via BPF
test_run).
This allows schedulers to implement a consistent idle CPU selection
policy and helps reduce code duplication.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit dfa0a574cb ("sched/uclamg: Handle delayed dequeue")
has add the sched_delayed check to prevent double uclamp_dec/inc.
However, it put the uclamp_rq_inc() after enqueue_task().
This may lead to the following issues:
When a task with uclamp goes through enqueue_task() and could trigger
cpufreq update, its uclamp won't even be considered in the cpufreq
update. It is only after enqueue will the uclamp be added to rq
buckets, and cpufreq will only pick it up at the next update.
This could cause a delay in frequency updating. It may affect
the performance(uclamp_min > 0) or power(uclamp_max < 1024).
So, just like util_est, put the uclamp_rq_inc() before enqueue_task().
And as for the sched_delayed_task, same as util_est, using the
sched_delayed flag to prevent inc the sched_delayed_task's uclamp,
using the ENQUEUE_DELAYED flag to allow inc the sched_delayed_task's uclamp
which is being woken up.
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20250417043457.10632-3-xuewen.yan@unisoc.com
To prevent double enqueue/dequeue of the util-est for sched_delayed tasks,
commit 729288bc68 ("kernel/sched: Fix util_est accounting for DELAY_DEQUEUE")
added the corresponding check. This check excludes double en/dequeue during
task migration and priority changes.
In fact, these conditions can be simplified.
For util_est_dequeue, we know that sched_delayed flag is set in dequeue_entity.
When the task is sleeping, we need to call util_est_dequeue to subtract
util-est from the cfs_rq. At this point, sched_delayed has not yet been set.
If we find that sched_delayed is already set, it indicates that this task
has already called dequeue_task_fair once. In this case, there is no need to
call util_est_dequeue again. Therefore, simply checking the sched_delayed flag
should be sufficient to prevent unnecessary util_est updates during the dequeue.
For util_est_enqueue, our goal is to add the util_est to the cfs_rq
when task enqueue. However, we don't want to add the util_est of a
sched_delayed task to the cfs_rq because the task is sleeping.
Therefore, we can exclude the util_est_enqueue for sched_delayed tasks
by checking the sched_delayed flag. However, when waking up a delayed task,
the sched_delayed flag is cleared after util_est_enqueue. As a result,
if we only check the sched_delayed flag, we would miss the util_est_enqueue.
Since waking up a sched_delayed task calls enqueue_task with the ENQUEUE_DELAYED flag,
we can determine whether to call util_est_enqueue by checking if the
enqueue_flag contains ENQUEUE_DELAYED.
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20250417043457.10632-2-xuewen.yan@unisoc.com
Delayed dequeued feature keeps a sleeping task enqueued until its
lag has elapsed. As a result, it stays also visible in rq->nr_running.
So when in wake_affine_idle(), we should use the real running-tasks
in rq to check whether we should place the wake-up task to
current cpu.
On the other hand, add a helper function to return the nr-delayed.
Fixes: 152e11f6df ("sched/fair: Implement delayed dequeue")
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Reviewed-and-tested-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250303105241.17251-2-xuewen.yan@unisoc.com
Allow scx_bpf_select_cpu_and() to be used from an unlocked context, in
addition to ops.enqueue() or ops.select_cpu().
This enables schedulers, including user-space ones, to implement a
consistent idle CPU selection policy and helps reduce code duplication.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Validate locking correctness when accessing p->nr_cpus_allowed and
p->cpus_ptr inside scx_bpf_select_cpu_and(): if the rq lock is held,
access is safe; otherwise, require that p->pi_lock is held.
This allows to catch potential unsafe calls to scx_bpf_select_cpu_and().
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Relocate the scx_kf_allowed_if_unlocked(), so it can be used from other
source files (e.g., ext_idle.c).
No functional change.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Naked scx_root dereferences are being used as temporary markers to indicate
that they need to be updated to point to the right scheduler instance.
Explain the situation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
In preparation of hierarchical scheduling support, add @sch to scx_exit()
and friends:
- scx_exit/error() updated to take explicit @sch instead of assuming
scx_root.
- scx_kf_exit/error() added. These are to be used from kfuncs, don't take
@sch and internally determine the scx_sched instance to abort. Currently,
it's always scx_root but once multiple scheduler support is in place, it
will be the scx_sched instance that invoked the kfunc. This simplifies
many callsites and defers scx_sched lookup until error is triggered.
- @sch is propagated to ops_cpu_valid() and ops_sanitize_err(). The CPU
validity conditions in ops_cpu_valid() are factored into __cpu_valid() to
implement kf_cpu_valid() which is the counterpart to scx_kf_exit/error().
- All users are converted. Most conversions are straightforward.
check_rq_for_timeouts() and scx_softlockup() are updated to use explicit
rcu_dereference*(scx_root) for safety as they may execute asynchronous to
the exit path. scx_tick() is also updated to use rcu_dereference(). While
not strictly necessary due to the preceding scx_enabled() test and IRQ
disabled context, this removes the subtlety at no noticeable cost.
No behavior changes intended.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
__scx_exit() is the base exit implementation and there are three wrappers on
top of it - scx_exit(), __scx_error() and scx_error(). This is more
confusing than helpful especially given that there are only a couple users
of scx_exit() and __scx_error(). To simplify the situation:
- Make __scx_exit() take va_list and rename it to scx_vexit(). This is to
ease implementing more complex extensions on top.
- Make scx_exit() a varargs wrapper around __scx_exit(). scx_exit() now
takes both @kind and @exit_code.
- Convert existing scx_exit() and __scx_error() users to use the new
scx_exit().
- scx_error() remains unchanged.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
In preparation of hierarchical scheduling support, make SCX_CALL_OP*() take
explicit @sch instead of assuming scx_root. As scx_root is still the only
scheduler instance, this patch doesn't make any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
- Always cache scx_root into local variable sch before using.
- Don't use scx_root if cached sch is available.
- Wrap !sch test with unlikely().
- Pass @scx into scx_cgroup_init/exit().
No behavior changes intended.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
With the goal of deprecating / removing VOLUNTARY preempt, live-patch
needs to stop relying on cond_resched() to make forward progress.
Instead, rely on schedule() with TASK_FREEZABLE set. Just like
live-patching, the freezer needs to be able to stop tasks in a safe /
known state.
[bigeasy: use likely() in __klp_sched_try_switch() and update comments]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Tested-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20250509113659.wkP_HJ5z@linutronix.de
Patch series "sched/numa: Skip VMA scanning on memory pinned to one NUMA
node via cpuset.mems", v5.
This patch (of 2):
When the memory of the current task is pinned to one NUMA node by cgroup,
there is no point in continuing the rest of VMA scanning and hinting page
faults as they will just be overhead. With this change, there will be no
more unnecessary PTE updates or page faults in this scenario.
We have seen up to a 6x improvement on a typical java workload running on
VMs with memory and CPU pinned to one NUMA node via cpuset in a two-socket
AARCH64 system. With the same pinning, on a 18-cores-per-socket Intel
platform, we have seen 20% improvment in a microbench that creates a
30-vCPU selftest KVM guest with 4GB memory, where each vCPU reads 4KB
pages in a fixed number of loops.
Link: https://lkml.kernel.org/r/20250424024523.2298272-1-libo.chen@oracle.com
Link: https://lkml.kernel.org/r/20250424024523.2298272-2-libo.chen@oracle.com
Signed-off-by: Libo Chen <libo.chen@oracle.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Chris Hyser <chris.hyser@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A little bit invasive for rc6 but they're important fixes, pass tests fine
and won't break anything outside sched_ext.
- scx_bpf_cpuperf_set() calls internal functions that require the rq to be
locked. It assumed that the BPF caller has rq locked but that's not always
true. Fix it by tracking whether rq is currently held by the CPU and
grabbing it if necessary.
- bpf_iter_scx_dsq_new() was leaving the DSQ iterator in an uninitialized
state after an error. However, next() and destroy() can be called on an
iterator which failed initialization and thus they always need to be
initialized even after an init error. Fix by always initializing the
iterator.
- Remove duplicate BTF_ID_FLAGS() entries.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCaCKYDw4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGV0nAP9UX1sGJV7a8by8L0hq3luZRSQo7Kjw0pTaMeD+
/oIlOgD/VX3epHmSKvwIOO2W4bv5oSR8B+Yx+4uAhhLfTgdlxgk=
=clg7
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.15-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"A little bit invasive for rc6 but they're important fixes, pass tests
fine and won't break anything outside sched_ext:
- scx_bpf_cpuperf_set() calls internal functions that require the rq
to be locked. It assumed that the BPF caller has rq locked but
that's not always true. Fix it by tracking whether rq is currently
held by the CPU and grabbing it if necessary
- bpf_iter_scx_dsq_new() was leaving the DSQ iterator in an
uninitialized state after an error. However, next() and destroy()
can be called on an iterator which failed initialization and thus
they always need to be initialized even after an init error. Fix by
always initializing the iterator
- Remove duplicate BTF_ID_FLAGS() entries"
* tag 'sched_ext-for-6.15-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: bpf_iter_scx_dsq_new() should always initialize iterator
sched_ext: Fix rq lock state in hotplug ops
sched_ext: Remove duplicate BTF_ID_FLAGS definitions
sched_ext: Fix missing rq lock in scx_bpf_cpuperf_set()
sched_ext: Track currently locked rq
task_storage_{get,delete} has been moved to bpf_base_func_proto.
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/bpf/20250506061434.94277-3-yangfeng59949@163.com
Doing cpufreq-specific EAS checks that require accessing policy
internals directly from sched_is_eas_possible() is a bit unfortunate,
so introduce cpufreq_ready_for_eas() in cpufreq, move those checks
into that new function and make sched_is_eas_possible() call it.
While at it, address a possible race between the EAS governor check
and governor change by doing the former under the policy rwsem.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/2317800.iZASKD2KPV@rjwysocki.net
Add a helper for checking if schedutil is the current governor for
a given cpufreq policy and use it in sched_is_eas_possible() to avoid
accessing cpufreq policy internals directly from there.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://patch.msgid.link/3365956.44csPzL39Z@rjwysocki.net
To receive 428dc9fc08 ("sched_ext: bpf_iter_scx_dsq_new() should always
initialize iterator") which conflicts with cdf5a6faa8 ("sched_ext: Move
dsq_hash into scx_sched"). The conflict is a simple context conflict which
can be resolved by taking changes from both changes in the right order.
BPF programs may call next() and destroy() on BPF iterators even after new()
returns an error value (e.g. bpf_for_each() macro ignores error returns from
new()). bpf_iter_scx_dsq_new() could leave the iterator in an uninitialized
state after an error return causing bpf_iter_scx_dsq_next() to dereference
garbage data. Make bpf_iter_scx_dsq_new() always clear $kit->dsq so that
next() and destroy() become noops.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 650ba21b13 ("sched_ext: Implement DSQ iterator")
Cc: stable@vger.kernel.org # v6.12+
Acked-by: Andrea Righi <arighi@nvidia.com>
A sched_ext scheduler may trigger __scx_exit() from a BPF timer
callback, where scx_root may not be safely dereferenced.
This can lead to a NULL pointer dereference as shown below (triggered by
scx_tickless):
BUG: kernel NULL pointer dereference, address: 0000000000000330
...
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-virtme #1 PREEMPT(full)
RIP: 0010:__scx_exit+0x2b/0x190
...
Call Trace:
<IRQ>
scx_bpf_get_idle_smtmask+0x59/0x80
bpf_prog_8320d4217989178c_dispatch_all_cpus+0x35/0x1b6
...
bpf_prog_97f847d871513f95_sched_timerfn+0x4c/0x264
bpf_timer_cb+0x7a/0x140
__hrtimer_run_queues+0x1f9/0x3a0
hrtimer_run_softirq+0x8c/0xd0
handle_softirqs+0xd3/0x3d0
__irq_exit_rcu+0x9a/0xc0
irq_exit_rcu+0xe/0x20
Fix this by checking for a valid scx_root and adding proper RCU
protection.
Fixes: 48e1267773 ("sched_ext: Introduce scx_sched")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Using a DSQ iterators from a timer callback can trigger the following
lockdep splat when accessing scx_root:
=============================
WARNING: suspicious RCU usage
6.14.0-virtme #1 Not tainted
-----------------------------
kernel/sched/ext.c:6907 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
no locks held by swapper/0/0.
stack backtrace:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-virtme #1 PREEMPT(full)
Sched_ext: tickless (enabled+all)
Call Trace:
<IRQ>
dump_stack_lvl+0x6f/0xb0
lockdep_rcu_suspicious.cold+0x4e/0xa3
bpf_iter_scx_dsq_new+0xb1/0xd0
bpf_prog_63f4fd1bccc101e7_dispatch_cpu+0x3e/0x156
bpf_prog_8320d4217989178c_dispatch_all_cpus+0x153/0x1b6
bpf_prog_97f847d871513f95_sched_timerfn+0x4c/0x264
? hrtimer_run_softirq+0x4f/0xd0
bpf_timer_cb+0x7a/0x140
__hrtimer_run_queues+0x1f9/0x3a0
hrtimer_run_softirq+0x8c/0xd0
handle_softirqs+0xd3/0x3d0
__irq_exit_rcu+0x9a/0xc0
irq_exit_rcu+0xe/0x20
sysvec_apic_timer_interrupt+0x73/0x80
Add a proper dereference check to explicitly validate RCU-safe access to
scx_root from rcu_read_lock() contexts and also from contexts that hold
rcu_read_lock_bh(), such as timer callbacks.
Fixes: cdf5a6faa8 ("sched_ext: Move dsq_hash into scx_sched")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was reported that in 6.12, smpboot_create_threads() was
taking much longer then in 6.6.
I narrowed down the call path to:
smpboot_create_threads()
-> kthread_create_on_cpu()
-> kthread_bind()
-> __kthread_bind_mask()
->wait_task_inactive()
Where in wait_task_inactive() we were regularly hitting the
queued case, which sets a 1 tick timeout, which when called
multiple times in a row, accumulates quickly into a long
delay.
I noticed disabling the DELAY_DEQUEUE sched feature recovered
the performance, and it seems the newly create tasks are usually
sched_delayed and left on the runqueue.
So in wait_task_inactive() when we see the task
p->se.sched_delayed, manually dequeue the sched_delayed task
with DEQUEUE_DELAYED, so we don't have to constantly wait a
tick.
Fixes: 152e11f6df ("sched/fair: Implement delayed dequeue")
Reported-by: peter-yc.chang@mediatek.com
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20250429150736.3778580-1-jstultz@google.com
With the global states and disable machinery moved into scx_sched,
scx_disable_workfn() can only be scheduled and run for the specific
scheduler instance. This makes it impossible for scx_disable_workfn() to see
SCX_EXIT_NONE. Turn that condition into WARN_ON_ONCE().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Because disable can be triggered from any place and the scheduler cannot be
trusted, disable path uses an irq_work to bounce and a kthread_work which is
executed on an RT helper kthread to perform disable. These must be per
scheduler instance to guarantee forward progress. Move them into scx_sched.
- If an scx_sched is accessible, its helper kthread is always valid making
the `helper` check in schedule_scx_disable_work() unnecessary. As the
function becomes trivial after the removal of the test, inline it.
- scx_create_rt_helper() has only one user - creation of the disable helper
kthread. Inline it into scx_alloc_and_add_sched().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
The event counters are going to become per scheduler instance. Move
event_stats_cpu into scx_sched.
- [__]scx_add_event() are updated to take @sch. While at it, add missing
parentheses around @cnt expansions.
- scx_read_events() is updated to take @sch.
- scx_bpf_events() accesses scx_root under RCU read lock.
v2: - Replace stale scx_bpf_get_event_stat() reference in a comment with
scx_bpf_events().
- Trivial goto label rename.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
In prepration of moving event_stats_cpu into scx_sched, factor out
scx_read_events() out of scx_bpf_events() and update the in-kernel users -
scx_attr_events_show() and scx_dump_state() - to use scx_read_events()
instead of scx_bpf_events(). No observable behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
In prepration of moving event_stats_cpu into scx_sched, move scx_event_stats
definitions above scx_sched definition. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Global DSQs are going to become per scheduler instance. Move global_dsqs
into scx_sched. find_global_dsq() already takes a task_struct pointer as an
argument and should later be able to determine the scx_sched to use from
that. For now, assume scx_root.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
User DSQs are going to become per scheduler instance. Move dsq_hash into
scx_sched. This shifts the code that assumes scx_root to be the only
scx_sched instance up the call stack but doesn't remove them yet.
v2: Add missing rcu_read_lock() in scx_bpf_destroy_dsq() as per Andrea.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
More will be moved into scx_sched. Factor out the allocation and kobject
addition path into scx_alloc_and_add_sched().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
create_dsq() is only used by scx_bpf_create_dsq() and the separation gets in
the way of making dsq_hash per scx_sched. Inline it into
scx_bpf_create_dsq(). While at it, add unlikely() around
SCX_DSQ_FLAG_BUILTIN test.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
To prepare for supporting multiple schedulers, make scx_sched allocated
dynamically. scx_sched->kobj is now an embedded field and the kobj's
lifetime determines the lifetime of the containing scx_sched.
- Enable path is updated so that kobj init and addition are performed later.
- scx_sched freeing is initiated in scx_kobj_release() and also goes through
an rcu_work so that scx_root can be accessed from an unsynchronized path -
scx_disable().
- sched_ext_ops->priv is added and used to point to scx_sched instance
created for the ops instance. This is used by bpf_scx_unreg() to determine
the scx_sched instance to disable and put.
No behavior changes intended.
v2: Andrea reported kernel oops due to scx_bpf_unreg() trying to deref NULL
scx_root after scheduler init failure. sched_ext_ops->priv added so that
scx_bpf_unreg() can always find the scx_sched instance to unregister
even if it failed early during init.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
SCX_HAS_OP() tests scx_root->has_op bitmap. The bitmap is currently in a
statically allocated struct scx_sched and initialized while loading the BPF
scheduler and cleared while unloading, and thus can be tested anytime.
However, scx_root will be switched to dynamic allocation and thus won't
always be deferenceable.
Most usages of SCX_HAS_OP() are already protected by scx_enabled() either
directly or indirectly (e.g. through a task which is on SCX). However, there
are a couple places that could try to dereference NULL scx_root. Update them
so that scx_root is guaranteed to be valid before SCX_HAS_OP() is called.
- In handle_hotplug(), test whether scx_root is NULL before doing anything
else. This is safe because scx_root updates will be protected by
cpus_read_lock().
- In scx_tg_offline(), test scx_cgroup_enabled before invoking SCX_HAS_OP(),
which should guarnatee that scx_root won't turn NULL. This is also in line
with other cgroup operations. As the code path is synchronized against
scx_cgroup_init/exit() through scx_cgroup_rwsem, this shouldn't cause any
behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
To support multiple scheduler instances, collect some of the global
variables that should be specific to a scheduler instance into the new
struct scx_sched. scx_root is the root scheduler instance and points to a
static instance of struct scx_sched. Except for an extra dereference through
the scx_root pointer, this patch makes no functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
The ops.cpu_online() and ops.cpu_offline() callbacks incorrectly assume
that the rq involved in the operation is locked, which is not the case
during hotplug, triggering the following warning:
WARNING: CPU: 1 PID: 20 at kernel/sched/sched.h:1504 handle_hotplug+0x280/0x340
Fix by not tracking the target rq as locked in the context of
ops.cpu_online() and ops.cpu_offline().
Fixes: 18853ba782 ("sched_ext: Track currently locked rq")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Tested-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[ Arguably if pick_eevdf()/pick_next_entity() was less trusting
of complex math being correct it could have de-escalated a
crash into a warning, but that's for a different patch. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=pJ11
-----END PGP SIGNATURE-----
Merge tag 'sched-urgent-2025-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"Fix sporadic crashes in dequeue_entities() due to ... bad math.
[ Arguably if pick_eevdf()/pick_next_entity() was less trusting of
complex math being correct it could have de-escalated a crash into
a warning, but that's for a different patch ]"
* tag 'sched-urgent-2025-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/eevdf: Fix se->slice being set to U64_MAX and resulting crash
There is a code path in dequeue_entities() that can set the slice of a
sched_entity to U64_MAX, which sometimes results in a crash.
The offending case is when dequeue_entities() is called to dequeue a
delayed group entity, and then the entity's parent's dequeue is delayed.
In that case:
1. In the if (entity_is_task(se)) else block at the beginning of
dequeue_entities(), slice is set to
cfs_rq_min_slice(group_cfs_rq(se)). If the entity was delayed, then
it has no queued tasks, so cfs_rq_min_slice() returns U64_MAX.
2. The first for_each_sched_entity() loop dequeues the entity.
3. If the entity was its parent's only child, then the next iteration
tries to dequeue the parent.
4. If the parent's dequeue needs to be delayed, then it breaks from the
first for_each_sched_entity() loop _without updating slice_.
5. The second for_each_sched_entity() loop sets the parent's ->slice to
the saved slice, which is still U64_MAX.
This throws off subsequent calculations with potentially catastrophic
results. A manifestation we saw in production was:
6. In update_entity_lag(), se->slice is used to calculate limit, which
ends up as a huge negative number.
7. limit is used in se->vlag = clamp(vlag, -limit, limit). Because limit
is negative, vlag > limit, so se->vlag is set to the same huge
negative number.
8. In place_entity(), se->vlag is scaled, which overflows and results in
another huge (positive or negative) number.
9. The adjusted lag is subtracted from se->vruntime, which increases or
decreases se->vruntime by a huge number.
10. pick_eevdf() calls entity_eligible()/vruntime_eligible(), which
incorrectly returns false because the vruntime is so far from the
other vruntimes on the queue, causing the
(vruntime - cfs_rq->min_vruntime) * load calulation to overflow.
11. Nothing appears to be eligible, so pick_eevdf() returns NULL.
12. pick_next_entity() tries to dereference the return value of
pick_eevdf() and crashes.
Dumping the cfs_rq states from the core dumps with drgn showed tell-tale
huge vruntime ranges and bogus vlag values, and I also traced se->slice
being set to U64_MAX on live systems (which was usually "benign" since
the rest of the runqueue needed to be in a particular state to crash).
Fix it in dequeue_entities() by always setting slice from the first
non-empty cfs_rq.
Fixes: aef6987d89 ("sched/eevdf: Propagate min_slice up the cgroup hierarchy")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/f0c2d1072be229e1bdddc73c0703919a8b00c652.1745570998.git.osandov@fb.com
Some kfuncs specific to the idle CPU selection policy are registered in
both the scx_kfunc_ids_any and scx_kfunc_ids_idle blocks, even though
they should only be defined in the latter.
Remove the duplicates from scx_kfunc_ids_any.
Fixes: 337d1b354a ("sched_ext: Move built-in idle CPU selection policy to a separate file")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The ops.running() and ops.stopping() callbacks can be invoked from a CPU
other than the one the task is assigned to, particularly when a task
property is changed, as both scx_next_task_scx() and dequeue_task_scx() may
run on CPUs different from the task's target CPU.
This behavior can lead to confusion or incorrect assumptions if not
properly clarified, potentially resulting in bugs (see [1]).
Therefore, update the documentation to clarify this aspect and advise
users to use scx_bpf_task_cpu() to determine the actual CPU the task
will run on or was running on.
[1] https://github.com/sched-ext/scx/pull/1728
Cc: Jake Hillion <jake@hillion.co.uk>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
a11d6784d7 ("sched_ext: Fix missing rq lock in scx_bpf_cpuperf_set()")
added a call to scx_ops_error() which was renamed to scx_error() in
for-6.16. Fix it up.
scx_bpf_cpuperf_set() can be used to set a performance target level on
any CPU. However, it doesn't correctly acquire the corresponding rq
lock, which may lead to unsafe behavior and trigger the following
warning, due to the lockdep_assert_rq_held() check:
[ 51.713737] WARNING: CPU: 3 PID: 3899 at kernel/sched/sched.h:1512 scx_bpf_cpuperf_set+0x1a0/0x1e0
...
[ 51.713836] Call trace:
[ 51.713837] scx_bpf_cpuperf_set+0x1a0/0x1e0 (P)
[ 51.713839] bpf_prog_62d35beb9301601f_bpfland_init+0x168/0x440
[ 51.713841] bpf__sched_ext_ops_init+0x54/0x8c
[ 51.713843] scx_ops_enable.constprop.0+0x2c0/0x10f0
[ 51.713845] bpf_scx_reg+0x18/0x30
[ 51.713847] bpf_struct_ops_link_create+0x154/0x1b0
[ 51.713849] __sys_bpf+0x1934/0x22a0
Fix by properly acquiring the rq lock when possible or raising an error
if we try to operate on a CPU that is not the one currently locked.
Fixes: d86adb4fc0 ("sched_ext: Add cpuperf support")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Some kfuncs provided by sched_ext may need to operate on a struct rq,
but they can be invoked from various contexts, specifically, different
scx callbacks.
While some of these callbacks are invoked with a particular rq already
locked, others are not. This makes it impossible for a kfunc to reliably
determine whether it's safe to access a given rq, triggering potential
bugs or unsafe behaviors, see for example [1].
To address this, track the currently locked rq whenever a sched_ext
callback is invoked via SCX_CALL_OP*().
This allows kfuncs that need to operate on an arbitrary rq to retrieve
the currently locked one and apply the appropriate action as needed.
[1] https://lore.kernel.org/lkml/20250325140021.73570-1-arighi@nvidia.com/
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
- Use kvzalloc() so that large exit_dump buffer allocations don't fail
easily.
- Remove cpu.weight / cpu.idle unimplemented warnings which are more
annoying than helpful. This makes SCX_OPS_HAS_CGROUP_WEIGHT unnecessary.
Mark it for deprecation.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCaAaeKw4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGcDjAQDM14FReObIKOOuqzlNaYXQqcSW2///ZVf/FR8j
HpWtyAD/Tsqg6CzBpTxKkpMRLsE2iKI1t770vkUnDbjcnR0Rxgc=
=rIV5
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.15-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Use kvzalloc() so that large exit_dump buffer allocations don't fail
easily
- Remove cpu.weight / cpu.idle unimplemented warnings which are more
annoying than helpful.
This makes SCX_OPS_HAS_CGROUP_WEIGHT unnecessary. Mark it for
deprecation
* tag 'sched_ext-for-6.15-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Mark SCX_OPS_HAS_CGROUP_WEIGHT for deprecation
sched_ext: Remove cpu.weight / cpu.idle unimplemented warnings
sched_ext: Use kvzalloc for large exit_dump allocation
Add helper for refilling task with default slice and event
statistics accordingly.
Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
when the tasks were enqueued, which seems not accurate. What it actually
means is the refilling with defalt slice, and this can occur either when
enqueue or pick_task. Let's change the variable to
SCX_EV_REFILL_SLICE_DFL.
Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Notice that ignore_dl_rate_limit() need not piggy back on the
limits_changed handling to achieve its goal (which is to enforce a
frequency update before its due time).
Namely, if sugov_should_update_freq() is updated to check
sg_policy->need_freq_update and return 'true' if it is set when
sg_policy->limits_changed is not set, ignore_dl_rate_limit() may
set the former directly instead of setting the latter, so it can
avoid hitting the memory barrier in sugov_should_update_freq().
Update the code accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/10666429.nUPlyArG6x@rjwysocki.net
The handling of the limits_changed flag in struct sugov_policy needs to
be explicitly synchronized to ensure that cpufreq policy limits updates
will not be missed in some cases.
Without that synchronization it is theoretically possible that
the limits_changed update in sugov_should_update_freq() will be
reordered with respect to the reads of the policy limits in
cpufreq_driver_resolve_freq() and in that case, if the limits_changed
update in sugov_limits() clobbers the one in sugov_should_update_freq(),
the new policy limits may not take effect for a long time.
Likewise, the limits_changed update in sugov_limits() may theoretically
get reordered with respect to the updates of the policy limits in
cpufreq_set_policy() and if sugov_should_update_freq() runs between
them, the policy limits change may be missed.
To ensure that the above situations will not take place, add memory
barriers preventing the reordering in question from taking place and
add READ_ONCE() and WRITE_ONCE() annotations around all of the
limits_changed flag updates to prevent the compiler from messing up
with that code.
Fixes: 600f5badb7 ("cpufreq: schedutil: Don't skip freq update when limits change")
Cc: 5.3+ <stable@vger.kernel.org> # 5.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/3376719.44csPzL39Z@rjwysocki.net
Commit 8e461a1cb4 ("cpufreq: schedutil: Fix superfluous updates caused
by need_freq_update") modified sugov_should_update_freq() to set the
need_freq_update flag only for drivers with CPUFREQ_NEED_UPDATE_LIMITS
set, but that flag generally needs to be set when the policy limits
change because the driver callback may need to be invoked for the new
limits to take effect.
However, if the return value of cpufreq_driver_resolve_freq() after
applying the new limits is still equal to the previously selected
frequency, the driver callback needs to be invoked only in the case
when CPUFREQ_NEED_UPDATE_LIMITS is set (which means that the driver
specifically wants its callback to be invoked every time the policy
limits change).
Update the code accordingly to avoid missing policy limits changes for
drivers without CPUFREQ_NEED_UPDATE_LIMITS.
Fixes: 8e461a1cb4 ("cpufreq: schedutil: Fix superfluous updates caused by need_freq_update")
Closes: https://lore.kernel.org/lkml/Z_Tlc6Qs-tYpxWYb@linaro.org/
Reported-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/3010358.e9J7NaK4W3@rjwysocki.net
Mike reports that commit 6d71a9c616 ("sched/fair: Fix EEVDF entity
placement bug causing scheduling lag") relies on commit 4423af84b2
("sched/fair: optimize the PLACE_LAG when se->vlag is zero") to not
trip a WARN in place_entity().
What happens is that the lag of the very last entity is 0 per
definition -- the average of one element matches the value of that
element. Therefore place_entity() will match the condition skipping
the lag adjustment:
if (sched_feat(PLACE_LAG) && cfs_rq->nr_queued && se->vlag) {
Without the 'se->vlag' condition -- it will attempt to adjust the zero
lag even though we're inserting into an empty tree.
Notably, we should have failed the 'cfs_rq->nr_queued' condition, but
don't because they didn't get updated.
Additionally, move update_load_add() after placement() as is
consistent with other place_entity() users -- this change is
non-functional, place_entity() does not use cfs_rq->load.
Fixes: 6d71a9c616 ("sched/fair: Fix EEVDF entity placement bug causing scheduling lag")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/c216eb4ef0e0e0029c600aefc69d56681cee5581.camel@gmx.de
Add a file to read local group's "asym_prefer_cpu" from debugfs. This
information was useful when debugging issues where "asym_prefer_cpu" was
incorrectly set to a CPU with a lower asym priority.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-5-kprateek.nayak@amd.com
A subset of AMD Processors supporting Preferred Core Rankings also
feature the ability to dynamically switch these rankings at runtime to
bias load balancing towards or away from the LLC domain with larger
cache.
To support dynamically updating "sg->asym_prefer_cpu" without needing to
rebuild the sched domain, introduce sched_update_asym_prefer_cpu() which
recomutes the "asym_prefer_cpu" when the core-ranking of a CPU changes.
sched_update_asym_prefer_cpu() swaps the "sg->asym_prefer_cpu" with the
CPU whose ranking has changed if the new ranking is greater than that of
the "asym_prefer_cpu". If CPU whose ranking has changed is the current
"asym_prefer_cpu", it scans the CPUs of the sched groups to find the new
"asym_prefer_cpu" and sets it accordingly.
get_group() for non-overlapping sched domains returns the sched group
for the first CPU in the sched_group_span() which ensures all CPUs in
the group see the updated value of "asym_prefer_cpu".
Overlapping groups are allocated differently and will require moving the
"asym_prefer_cpu" to "sg->sgc" but since the current implementations do
not set "SD_ASYM_PACKING" at NUMA domains, skip additional
indirection and place a SCHED_WARN_ON() to alert any future users.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-3-kprateek.nayak@amd.com
Subsequent commits add the support to dynamically update the sched_group
struct's "asym_prefer_cpu" member from a remote CPU. Use READ_ONCE()
when reading the "sg->asym_prefer_cpu" to ensure load balancer always
reads the latest value.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-2-kprateek.nayak@amd.com
scx_has_op is used to encode which ops are implemented by the BPF scheduler
into an array of static_keys. While this saves a bit of branching overhead,
that is unlikely to be noticeable compared to the overall cost. As the
global static_keys can't work with the planned hierarchical multiple
scheduler support, replace the static_key array with a bitmap.
In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
scx_ops_allow_queued_wakeup is used to encode SCX_OPS_ALLOW_QUEUED_WAKEUP
into a static_key. The test is gated behind scx_enabled(), and, even when
sched_ext is enabled, is unlikely for the static_key usage to make any
meaningful difference. It is made to use a static_key mostly because there
was no reason not to. However, global static_keys can't work with the
planned hierarchical multiple scheduler support. Remove the static_key and
instead test SCX_OPS_ALLOW_QUEUED_WAKEUP directly.
In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
scx_ops_cpu_preempt is used to encode whether ops.cpu_acquire/release() are
implemented into a static_key. These tests aren't hot enough for static_key
usage to make any meaningful difference and are made to use a static_key
mostly because there was no reason not to. However, global static_keys can't
work with the planned hierarchical multiple scheduler support. Remove the
static_key and instead use an internal ops flag SCX_OPS_HAS_CPU_PREEMPT to
record and test whether ops.cpu_acquire/release() are implemented.
In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
scx_ops_enq_last/exiting/migration_disabled are used to encode the
corresponding SCX_OPS_ flags into static_keys. These flags aren't hot enough
for static_key usage to make any meaningful difference and are made
static_keys mostly because there was no reason not to. However, global
static_keys can't work with the planned hierarchical multiple scheduler
support. Remove the static_keys and test the ops flags directly.
In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Pull for-6.15-fixes to receive:
e776b26e37 ("sched_ext: Remove cpu.weight / cpu.idle unimplemented warnings")
which conflicts with:
1a7ff7216c ("sched_ext: Drop "ops" from scx_ops_enable_state and friends")
The former removes code updated by the latter. Resolved by removing the
updated section.
Signed-off-by: Tejun Heo <tj@kernel.org>
The exising code uses housekeeping_any_cpu() to select a cpu for
a given housekeeping task. However, this often ends up calling
cpumask_any_and() which is defined as cpumask_first_and() which has
the effect of alyways using the first cpu among those available.
The same applies when multiple NUMA nodes are involved. In that
case the first cpu in the local node is chosen which does provide
a bit of spreading but with multiple HK cpus per node the same
issues arise.
We have numerous cases where a single HK cpu just cannot keep up
and the remote_tick warning fires. It also can lead to the other
things (orchastration sw, HA keepalives etc) on the HK cpus getting
starved which leads to other issues. In these cases we recommend
increasing the number of HK cpus. But... that only helps the
userspace tasks somewhat. It does not help the actual housekeeping
part.
Spread the HK work out by having housekeeping_any_cpu() and
sched_numa_find_closest() use cpumask_any_and_distribute()
instead of cpumask_any_and().
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Vishal Chourasia <vishalc@linux.ibm.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20250218184618.1331715-1-pauld@redhat.com
Overview
========
When a CPU chooses to call push_rt_task and picks a task to push to
another CPU's runqueue then it will call find_lock_lowest_rq method
which would take a double lock on both CPUs' runqueues. If one of the
locks aren't readily available, it may lead to dropping the current
runqueue lock and reacquiring both the locks at once. During this window
it is possible that the task is already migrated and is running on some
other CPU. These cases are already handled. However, if the task is
migrated and has already been executed and another CPU is now trying to
wake it up (ttwu) such that it is queued again on the runqeue
(on_rq is 1) and also if the task was run by the same CPU, then the
current checks will pass even though the task was migrated out and is no
longer in the pushable tasks list.
Crashes
=======
This bug resulted in quite a few flavors of crashes triggering kernel
panics with various crash signatures such as assert failures, page
faults, null pointer dereferences, and queue corruption errors all
coming from scheduler itself.
Some of the crashes:
-> kernel BUG at kernel/sched/rt.c:1616! BUG_ON(idx >= MAX_RT_PRIO)
Call Trace:
? __die_body+0x1a/0x60
? die+0x2a/0x50
? do_trap+0x85/0x100
? pick_next_task_rt+0x6e/0x1d0
? do_error_trap+0x64/0xa0
? pick_next_task_rt+0x6e/0x1d0
? exc_invalid_op+0x4c/0x60
? pick_next_task_rt+0x6e/0x1d0
? asm_exc_invalid_op+0x12/0x20
? pick_next_task_rt+0x6e/0x1d0
__schedule+0x5cb/0x790
? update_ts_time_stats+0x55/0x70
schedule_idle+0x1e/0x40
do_idle+0x15e/0x200
cpu_startup_entry+0x19/0x20
start_secondary+0x117/0x160
secondary_startup_64_no_verify+0xb0/0xbb
-> BUG: kernel NULL pointer dereference, address: 00000000000000c0
Call Trace:
? __die_body+0x1a/0x60
? no_context+0x183/0x350
? __warn+0x8a/0xe0
? exc_page_fault+0x3d6/0x520
? asm_exc_page_fault+0x1e/0x30
? pick_next_task_rt+0xb5/0x1d0
? pick_next_task_rt+0x8c/0x1d0
__schedule+0x583/0x7e0
? update_ts_time_stats+0x55/0x70
schedule_idle+0x1e/0x40
do_idle+0x15e/0x200
cpu_startup_entry+0x19/0x20
start_secondary+0x117/0x160
secondary_startup_64_no_verify+0xb0/0xbb
-> BUG: unable to handle page fault for address: ffff9464daea5900
kernel BUG at kernel/sched/rt.c:1861! BUG_ON(rq->cpu != task_cpu(p))
-> kernel BUG at kernel/sched/rt.c:1055! BUG_ON(!rq->nr_running)
Call Trace:
? __die_body+0x1a/0x60
? die+0x2a/0x50
? do_trap+0x85/0x100
? dequeue_top_rt_rq+0xa2/0xb0
? do_error_trap+0x64/0xa0
? dequeue_top_rt_rq+0xa2/0xb0
? exc_invalid_op+0x4c/0x60
? dequeue_top_rt_rq+0xa2/0xb0
? asm_exc_invalid_op+0x12/0x20
? dequeue_top_rt_rq+0xa2/0xb0
dequeue_rt_entity+0x1f/0x70
dequeue_task_rt+0x2d/0x70
__schedule+0x1a8/0x7e0
? blk_finish_plug+0x25/0x40
schedule+0x3c/0xb0
futex_wait_queue_me+0xb6/0x120
futex_wait+0xd9/0x240
do_futex+0x344/0xa90
? get_mm_exe_file+0x30/0x60
? audit_exe_compare+0x58/0x70
? audit_filter_rules.constprop.26+0x65e/0x1220
__x64_sys_futex+0x148/0x1f0
do_syscall_64+0x30/0x80
entry_SYSCALL_64_after_hwframe+0x62/0xc7
-> BUG: unable to handle page fault for address: ffff8cf3608bc2c0
Call Trace:
? __die_body+0x1a/0x60
? no_context+0x183/0x350
? spurious_kernel_fault+0x171/0x1c0
? exc_page_fault+0x3b6/0x520
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? asm_exc_page_fault+0x1e/0x30
? _cond_resched+0x15/0x30
? futex_wait_queue_me+0xc8/0x120
? futex_wait+0xd9/0x240
? try_to_wake_up+0x1b8/0x490
? futex_wake+0x78/0x160
? do_futex+0xcd/0xa90
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? plist_del+0x6a/0xd0
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? dequeue_pushable_task+0x20/0x70
? __schedule+0x382/0x7e0
? asm_sysvec_reschedule_ipi+0xa/0x20
? schedule+0x3c/0xb0
? exit_to_user_mode_prepare+0x9e/0x150
? irqentry_exit_to_user_mode+0x5/0x30
? asm_sysvec_reschedule_ipi+0x12/0x20
Above are some of the common examples of the crashes that were observed
due to this issue.
Details
=======
Let's look at the following scenario to understand this race.
1) CPU A enters push_rt_task
a) CPU A has chosen next_task = task p.
b) CPU A calls find_lock_lowest_rq(Task p, CPU Z’s rq).
c) CPU A identifies CPU X as a destination CPU (X < Z).
d) CPU A enters double_lock_balance(CPU Z’s rq, CPU X’s rq).
e) Since X is lower than Z, CPU A unlocks CPU Z’s rq. Someone else has
locked CPU X’s rq, and thus, CPU A must wait.
2) At CPU Z
a) Previous task has completed execution and thus, CPU Z enters
schedule, locks its own rq after CPU A releases it.
b) CPU Z dequeues previous task and begins executing task p.
c) CPU Z unlocks its rq.
d) Task p yields the CPU (ex. by doing IO or waiting to acquire a
lock) which triggers the schedule function on CPU Z.
e) CPU Z enters schedule again, locks its own rq, and dequeues task p.
f) As part of dequeue, it sets p.on_rq = 0 and unlocks its rq.
3) At CPU B
a) CPU B enters try_to_wake_up with input task p.
b) Since CPU Z dequeued task p, p.on_rq = 0, and CPU B updates
B.state = WAKING.
c) CPU B via select_task_rq determines CPU Y as the target CPU.
4) The race
a) CPU A acquires CPU X’s lock and relocks CPU Z.
b) CPU A reads task p.cpu = Z and incorrectly concludes task p is
still on CPU Z.
c) CPU A failed to notice task p had been dequeued from CPU Z while
CPU A was waiting for locks in double_lock_balance. If CPU A knew
that task p had been dequeued, it would return NULL forcing
push_rt_task to give up the task p's migration.
d) CPU B updates task p.cpu = Y and calls ttwu_queue.
e) CPU B locks Ys rq. CPU B enqueues task p onto Y and sets task
p.on_rq = 1.
f) CPU B unlocks CPU Y, triggering memory synchronization.
g) CPU A reads task p.on_rq = 1, cementing its assumption that task p
has not migrated.
h) CPU A decides to migrate p to CPU X.
This leads to A dequeuing p from Y's queue and various crashes down the
line.
Solution
========
The solution here is fairly simple. After obtaining the lock (at 4a),
the check is enhanced to make sure that the task is still at the head of
the pushable tasks list. If not, then it is anyway not suitable for
being pushed out.
Testing
=======
The fix is tested on a cluster of 3 nodes, where the panics due to this
are hit every couple of days. A fix similar to this was deployed on such
cluster and was stable for more than 30 days.
Co-developed-by: Jon Kohler <jon@nutanix.com>
Signed-off-by: Jon Kohler <jon@nutanix.com>
Co-developed-by: Gauri Patwardhan <gauri.patwardhan@nutanix.com>
Signed-off-by: Gauri Patwardhan <gauri.patwardhan@nutanix.com>
Co-developed-by: Rahul Chunduru <rahul.chunduru@nutanix.com>
Signed-off-by: Rahul Chunduru <rahul.chunduru@nutanix.com>
Signed-off-by: Harshit Agarwal <harshit@nutanix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Tested-by: Will Ton <william.ton@nutanix.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250225180553.167995-1-harshit@nutanix.com
With CONFIG_RT_GROUP_SCHED but runtime disabling of RT_GROUPs we expect
the existence of the root task_group only and all rt_sched_entity'ies
should be queued on root's rt_rq.
If we get a non-root RT_GROUP something went wrong.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-9-mkoutny@suse.com
Thanks to kernel cmdline being available early, before any
cgroup hierarchy exists, we can achieve the RT_GROUP_SCHED boottime
disabling goal by simply skipping any creation (and destruction) of
RT_GROUP data and its exposure via RT attributes.
We can do this thanks to previously placed runtime guards that would
redirect all operations to root_task_group's data when RT_GROUP_SCHED
disabled.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-8-mkoutny@suse.com
When RT_GROUPs are compiled but not exposed, their bandwidth cannot
be configured (and it is not initialized for non-root task_groups neither).
Therefore bypass any checks of task vs task_group bandwidth.
This will achieve behavior very similar to setups that have
!CONFIG_RT_GROUP_SCHED and attach cpu controller to cgroup v2 hierarchy.
(On a related note, this may allow having RT tasks with
CONFIG_RT_GROUP_SCHED and cgroup v2 hierarchy.)
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-7-mkoutny@suse.com
First, we want to prevent placement of RT tasks on non-root rt_rqs which
we achieve in the task migration code that'd fall back to
root_task_group's rt_rq.
Second, we want to work with only root_task_group's rt_rq when iterating
all "real" rt_rqs when RT_GROUP is disabled. To achieve this we keep
root_task_group as the first one on the task_groups and break out
quickly.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-6-mkoutny@suse.com
rt_rq->tg may be NULL which denotes the root task_group.
Store the pointer to root_task_group directly so that callers may use
rt_rq->tg homogenously.
root_task_group exists always with CONFIG_CGROUPS_SCHED,
CONFIG_RT_GROUP_SCHED depends on that.
This changes root level rt_rq's default limit from infinity to the
value of (originally) global RT throttling.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-4-mkoutny@suse.com
rt_entity_is_task has split definitions based on CONFIG_RT_GROUP_SCHED,
therefore we can use it always. No functional change intended.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-3-mkoutny@suse.com
Convert the blocks guarded by macros to regular code so that the RT
group code gets more compile validation. Reasoning is in
Documentation/process/coding-style.rst 21) Conditional Compilation.
With that, no functional change is expected.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-2-mkoutny@suse.com
commit 10a35e6812 ("sched/pelt: Skip updating util_est when
utilization is higher than CPU's capacity")
prevents util_est from being updated if util_avg is higher than the
underlying CPU capacity to avoid overestimating the task when the CPU
is capped (due to thermal issue for instance). In this scenario, the
task will miss its deadlines and start overlapping its wake-up events
for instance. The task will appear as always running when the CPU is
just not powerful enough to allow having a good estimation of the
task.
commit b8c9636140 ("sched/fair/util_est: Implement faster ramp-up
EWMA on utilization increases")
sets ewma to util_avg when ewma > util_avg, allowing ewma to quickly
grow instead of slowly converge to the new util_avg value when a task
profile changes from small to big.
However, the 2 conditions:
- Check util_avg against max CPU capacity
- Check whether util_est > util_avg
are placed in an order such as it is possible to set util_est to a
value higher than the CPU capacity if util_est > util_avg, but
util_est is prevented to decay as long as:
CPU capacity < util_avg < util_est.
Just remove the check as either:
1.
There is idle time on the CPU. In that case the util_avg value of the
task is actually correct. It is possible that the task missed a
deadline and appears bigger, but this is also the case when the
util_avg of the task is lower than the maximum CPU capacity.
2.
There is no idle time. In that case, the util_avg value might aswell
be an under estimation of the size of the task.
It is possible that undesired frequency spikes will appear when the
task is later enqueued with an inflated util_est value, but the
frequency spike might aswell be deserved. The absence of idle time
prevents from drawing any conclusion.
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.rog>
Link: https://lore.kernel.org/r/20250325150542.1077344-1-pierre.gondois@arm.com
Simplify the topology_span_sane code further, removing the need to
allocate an array and gotos used to make sure the array gets freed.
This version is in a separate commit because it could return a
different sanity result than the previous code, but only in odd
circumstances that are not expected to actually occur; for example,
when a CPU is not listed in its own mask.
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Link: https://lore.kernel.org/r/20250304160844.75373-3-steve.wahl@hpe.com
Use a different approach to topology_span_sane(), that checks for the
same constraint of no partial overlaps for any two CPU sets for
non-NUMA topology levels, but does so in a way that is O(N) rather
than O(N^2).
Instead of comparing with all other masks to detect collisions, keep
one mask that includes all CPUs seen so far and detect collisions with
a single cpumask_intersects test.
If the current mask has no collisions with previously seen masks, it
should be a new mask, which can be uniquely identified by the lowest
bit set in this mask. Keep a pointer to this mask for future
reference (in an array indexed by the lowest bit set), and add the
CPUs in this mask to the list of those seen.
If the current mask does collide with previously seen masks, it should
be exactly equal to a mask seen before, looked up in the same array
indexed by the lowest bit set in the mask, a single comparison.
Move the topology_span_sane() check out of the existing topology level
loop, let it use its own loop so that the array allocation can be done
only once, shared across levels.
On a system with 1920 processors (16 sockets, 60 cores, 2 threads),
the average time to take one processor offline is reduced from 2.18
seconds to 1.01 seconds. (Off-lining 959 of 1920 processors took
34m49.765s without this change, 16m10.038s with this change in place.)
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Link: https://lore.kernel.org/r/20250304160844.75373-2-steve.wahl@hpe.com
Gabriele noted that in case of signal_pending_state(), the tracepoint
sees a stale task-state.
Fixes: fa2c3254d7 ("sched/tracing: Don't re-read p->state when emitting sched_switch event")
Reported-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Valentin Schneider <vschneid@redhat.com>
SCX_OPS_HAS_CGROUP_WEIGHT was only used to suppress the missing cgroup
weight support warnings. Now that the warnings are removed, the flag doesn't
do anything. Mark it for deprecation and remove its usage from scx_flatcg.
v2: Actually include the scx_flatcg update.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-and-reviewed-by: Andrea Righi <arighi@nvidia.com>
sched_ext generates warnings when cpu.weight / cpu.idle are set to
non-default values if the BPF scheduler doesn't implement weight support.
These warnings don't provide much value while adding constant annoyance. A
BPF scheduler may not implement any particular behavior and there's nothing
particularly special about missing cgroup weight support. Drop the warnings.
Signed-off-by: Tejun Heo <tj@kernel.org>
Replace kzalloc with kvzalloc for the exit_dump buffer allocation, which
can require large contiguous memory depending on the implementation.
This change prevents allocation failures by allowing the system to fall
back to vmalloc when contiguous memory allocation fails.
Since this buffer is only used for debugging purposes, physical memory
contiguity is not required, making vmalloc a suitable alternative.
Cc: stable@vger.kernel.org
Fixes: 07814a9439 ("sched_ext: Print debug dump after an error exit")
Suggested-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Provide a new kfunc, scx_bpf_select_cpu_and(), that can be used to apply
the built-in idle CPU selection policy to a subset of allowed CPU.
This new helper is basically an extension of scx_bpf_select_cpu_dfl().
However, when an idle CPU can't be found, it returns a negative value
instead of @prev_cpu, aligning its behavior more closely with
scx_bpf_pick_idle_cpu().
It also accepts %SCX_PICK_IDLE_* flags, which can be used to enforce
strict selection to @prev_cpu's node (%SCX_PICK_IDLE_IN_NODE), or to
request only a full-idle SMT core (%SCX_PICK_IDLE_CORE), while applying
the built-in selection logic.
With this helper, BPF schedulers can apply the built-in idle CPU
selection policy restricted to any arbitrary subset of CPUs.
Example usage
=============
Possible usage in ops.select_cpu():
s32 BPF_STRUCT_OPS(foo_select_cpu, struct task_struct *p,
s32 prev_cpu, u64 wake_flags)
{
const struct cpumask *cpus = task_allowed_cpus(p) ?: p->cpus_ptr;
s32 cpu;
cpu = scx_bpf_select_cpu_and(p, prev_cpu, wake_flags, cpus, 0);
if (cpu >= 0) {
scx_bpf_dsq_insert(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, 0);
return cpu;
}
return prev_cpu;
}
Results
=======
Load distribution on a 4 sockets, 4 cores per socket system, simulated
using virtme-ng, running a modified version of scx_bpfland that uses
scx_bpf_select_cpu_and() with 0xff00 as the allowed subset of CPUs:
$ vng --cpu 16,sockets=4,cores=4,threads=1
...
$ stress-ng -c 16
...
$ htop
...
0[ 0.0%] 8[||||||||||||||||||||||||100.0%]
1[ 0.0%] 9[||||||||||||||||||||||||100.0%]
2[ 0.0%] 10[||||||||||||||||||||||||100.0%]
3[ 0.0%] 11[||||||||||||||||||||||||100.0%]
4[ 0.0%] 12[||||||||||||||||||||||||100.0%]
5[ 0.0%] 13[||||||||||||||||||||||||100.0%]
6[ 0.0%] 14[||||||||||||||||||||||||100.0%]
7[ 0.0%] 15[||||||||||||||||||||||||100.0%]
With scx_bpf_select_cpu_dfl() tasks would be distributed evenly across
all the available CPUs.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Many scx schedulers implement their own hard or soft-affinity rules
to support topology characteristics, such as heterogeneous architectures
(e.g., big.LITTLE, P-cores/E-cores), or to categorize tasks based on
specific properties (e.g., running certain tasks only in a subset of
CPUs).
Currently, there is no mechanism that allows to use the built-in idle
CPU selection policy to an arbitrary subset of CPUs. As a result,
schedulers often implement their own idle CPU selection policies, which
are typically similar to one another, leading to a lot of code
duplication.
To address this, modify scx_select_cpu_dfl() to accept an arbitrary
cpumask, that can be used by the BPF schedulers to apply the existent
built-in idle CPU selection policy to a subset of allowed CPUs.
With this concept the idle CPU selection policy becomes the following:
- always prioritize CPUs from fully idle SMT cores (if SMT is enabled),
- select the same CPU if it's idle and in the allowed CPUs,
- select an idle CPU within the same LLC, if the LLC cpumask is a
subset of the allowed CPUs,
- select an idle CPU within the same node, if the node cpumask is a
subset of the allowed CPUs,
- select an idle CPU within the allowed CPUs.
This functionality will be exposed through a dedicated kfunc in a
separate patch.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Modify scx_select_cpu_dfl() to take the allowed cpumask as an explicit
argument, instead of implicitly using @p->cpus_ptr.
This prepares for future changes where arbitrary cpumasks may be passed
to the built-in idle CPU selection policy.
This is a pure refactoring with no functional changes.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The built-in idle selection policy, scx_select_cpu_dfl(), always
prioritizes picking idle CPUs within the same LLC or NUMA node, but
these optimizations are currently applied only when a task has no CPU
affinity constraints.
This is done primarily for efficiency, as it avoids the overhead of
updating a cpumask every time we need to select an idle CPU (which can
be costly in large SMP systems).
However, this approach limits the effectiveness of the built-in idle
policy and results in inconsistent behavior, as affinity-restricted
tasks don't benefit from topology-aware optimizations.
To address this, modify the policy to apply LLC and NUMA-aware
optimizations even when a task is constrained to a subset of CPUs.
We can still avoid updating the cpumasks by checking if the subset of
LLC and node CPUs are contained in the subset of allowed CPUs usable by
the task (which is true in most of the cases - for tasks that don't have
affinity constratints).
Moreover, use temporary local per-CPU cpumasks to determine the LLC and
node subsets, minimizing potential overhead even on large SMP systems.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.
Conversion was done with coccinelle plus manual fixups where necessary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from SCX_OPS_TASK_ITER_BATCH.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-and-acked-by: Andrea Righi <arighi@nvidia.com>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_{init|exit|enable|disable}[_task]() and friends.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_exit(), scx_ops_error() and friends.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_bypass(), scx_ops_breather() and friends. Update
scx_show_state.py accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_helper, scx_ops_enable_mutex and __scx_ops_enabled.
Update scx_show_state.py accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
The tag "ops" is used for two different purposes. First, to indicate that
the entity is directly related to the operations such as flags carried in
sched_ext_ops. Second, to indicate that the entity applies to something
global such as enable or bypass states. The second usage is historical and
causes confusion rather than clarifying anything. For example,
scx_ops_enable_state enums are named SCX_OPS_* and thus conflict with
scx_ops_flags. Let's drop the second usages.
Drop "ops" from scx_ops_enable_state and friends. Update scx_show_state.py
accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
- Calling scx_bpf_create_dsq() with the same ID would succeed creating
duplicate DSQs. Fix it to return -EEXIST.
- scx_select_cpu_dfl() fixes and cleanups.
- Synchronize tool/sched_ext with external scheduler repo. While this isn't
a fix. There's no risk to the kernel and it's better if they stay synced
closer.
-----BEGIN PGP SIGNATURE-----
iIMEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCZ+29Eg4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGeNGAP97GCCCwovepx3f9HV3RRk8oEregsGI7gmr+TC5
+XJrqwD4urg6I5JGM3K5dB9m626RyUP6k5RmYdjqBrEL6LauCg==
=uWzD
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.15-rc0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Calling scx_bpf_create_dsq() with the same ID would succeed creating
duplicate DSQs. Fix it to return -EEXIST.
- scx_select_cpu_dfl() fixes and cleanups.
- Synchronize tool/sched_ext with external scheduler repo. While this
isn't a fix. There's no risk to the kernel and it's better if they
stay synced closer.
* tag 'sched_ext-for-6.15-rc0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
tools/sched_ext: Sync with scx repo
sched_ext: initialize built-in idle state before ops.init()
sched_ext: create_dsq: Return -EEXIST on duplicate request
sched_ext: Remove a meaningless conditional goto in scx_select_cpu_dfl()
sched_ext: idle: Fix return code of scx_select_cpu_dfl()
Eliminate a useless task_work on execve by moving the call to
rseq_set_notify_resume() from sched_mm_cid_after_execve() to the error
path of bprm_execve().
The call to rseq_set_notify_resume() from sched_mm_cid_after_execve() is
pointless in the success case, because rseq_execve() will clear the rseq
pointer before returning to userspace.
sched_mm_cid_after_execve() is called from both the success and error
paths of bprm_execve(). The call to rseq_set_notify_resume() is needed
on error because the mm_cid may have changed.
Also move the rseq_execve() to right after sched_mm_cid_after_execve()
in bprm_execve().
[ mingo: Merged to a recent upstream kernel, extended the changelog. ]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250327132945.1558783-1-mathieu.desnoyers@efficios.com
- Add some trace events to osnoise and timerlat sample generation
This adds more information to the osnoise and timerlat tracers as well as
allows BPF programs to be attached to these locations to extract even more
data.
- Fix to DECLARE_TRACE_CONDITION() macro
It wasn't used but now will be and it happened to be broken causing the
build to fail.
- Add scheduler specification monitors to runtime verifier (RV)
This is a continuation of Daniel Bristot's work.
RV allows monitors to run and react concurrently. Running the cumulative
model is equivalent to running single components using the same
reactors, with the advantage that it's easier to point out which
specification failed in case of error.
This update introduces nested monitors to RV, in short, the sysfs
monitor folder will contain a monitor named sched, which is nothing but
an empty container for other monitors. Controlling the sched monitor
(enable, disable, set reactors) controls all nested monitors.
The following scheduling monitors are added:
* sco: scheduling context operations
Monitor to ensure sched_set_state happens only in thread context
* tss: task switch while scheduling
Monitor to ensure sched_switch happens only in scheduling context
* snroc: set non runnable on its own context
Monitor to ensure set_state happens only in the respective task's context
* scpd: schedule called with preemption disabled
Monitor to ensure schedule is called with preemption disabled
* snep: schedule does not enable preempt
Monitor to ensure schedule does not enable preempt
* sncid: schedule not called with interrupt disabled
Monitor to ensure schedule is not called with interrupt disabled
-----BEGIN PGP SIGNATURE-----
iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZ+QhuxQccm9zdGVkdEBn
b29kbWlzLm9yZwAKCRAp5XQQmuv6qg62AP9bkeNDbiCuAqjZGddV09Hw26wC3yum
kQoNSebD8G52rQEA9GDjK37xGzYwW/fJokhJVTV39qfub6inAJE5dS6WeQY=
=8Ikv
-----END PGP SIGNATURE-----
Merge tag 'trace-latency-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull latency tracing updates from Steven Rostedt:
- Add some trace events to osnoise and timerlat sample generation
This adds more information to the osnoise and timerlat tracers as
well as allows BPF programs to be attached to these locations to
extract even more data.
- Fix to DECLARE_TRACE_CONDITION() macro
It wasn't used but now will be and it happened to be broken causing
the build to fail.
- Add scheduler specification monitors to runtime verifier (RV)
This is a continuation of Daniel Bristot's work.
RV allows monitors to run and react concurrently. Running the
cumulative model is equivalent to running single components using the
same reactors, with the advantage that it's easier to point out which
specification failed in case of error.
This update introduces nested monitors to RV, in short, the sysfs
monitor folder will contain a monitor named sched, which is nothing
but an empty container for other monitors. Controlling the sched
monitor (enable, disable, set reactors) controls all nested monitors.
The following scheduling monitors are added:
- sco: scheduling context operations
Monitor to ensure sched_set_state happens only in thread context
- tss: task switch while scheduling
Monitor to ensure sched_switch happens only in scheduling context
- snroc: set non runnable on its own context
Monitor to ensure set_state happens only in the respective task's context
- scpd: schedule called with preemption disabled
Monitor to ensure schedule is called with preemption disabled
- snep: schedule does not enable preempt
Monitor to ensure schedule does not enable preempt
- sncid: schedule not called with interrupt disabled
Monitor to ensure schedule is not called with interrupt disabled
* tag 'trace-latency-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tools/rv: Allow rv list to filter for container
Documentation/rv: Add docs for the sched monitors
verification/dot2k: Add support for nested monitors
tools/rv: Add support for nested monitors
rv: Add scpd, snep and sncid per-cpu monitors
rv: Add snroc per-task monitor
rv: Add sco and tss per-cpu monitors
rv: Add option for nested monitors and include sched
sched: Add sched tracepoints for RV task model
rv: Add license identifiers to monitor files
tracing: Fix DECLARE_TRACE_CONDITION
trace/osnoise: Add trace events for samples
A BPF scheduler may want to use the built-in idle cpumasks in ops.init()
before the scheduler is fully initialized, either directly or through a
BPF timer for example.
However, this would result in an error, since the idle state has not
been properly initialized yet.
This can be easily verified by modifying scx_simple to call
scx_bpf_get_idle_cpumask() in ops.init():
$ sudo scx_simple
DEBUG DUMP
===========================================================================
scx_simple[121] triggered exit kind 1024:
runtime error (built-in idle tracking is disabled)
...
Fix this by properly initializing the idle state before ops.init() is
called. With this change applied:
$ sudo scx_simple
local=2 global=0
local=19 global=11
local=23 global=11
...
Fixes: d73249f887 ("sched_ext: idle: Make idle static keys private")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
create_dsq and therefore the scx_bpf_create_dsq kfunc currently silently
ignore duplicate entries. As a sched_ext scheduler is creating each DSQ
for a different purpose this is surprising behaviour.
Replace rhashtable_insert_fast which ignores duplicates with
rhashtable_lookup_insert_fast that reports duplicates (though doesn't
return their value). The rest of the code is structured correctly and
this now returns -EEXIST.
Tested by adding an extra scx_bpf_create_dsq to scx_simple. Previously
this was ignored, now init fails with a -17 code. Also ran scx_lavd
which continued to work well.
Signed-off-by: Jake Hillion <jake@hillion.co.uk>
Acked-by: Andrea Righi <arighi@nvidia.com>
Fixes: f0e1a0643a ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_select_cpu_dfl() has a meaningless conditional goto at the end. Remove
it. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <arighi@nvidia.com>
Return -EBUSY when using %SCX_PICK_IDLE_CORE with scx_select_cpu_dfl()
if a fully idle SMT core cannot be found, instead of falling back to
@prev_cpu, which is not a fully idle SMT core in this case.
Fixes: c414c2171c ("sched_ext: idle: Honor idle flags in the built-in idle selection policy")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
hrtimers are initialized with hrtimer_init() and a subsequent store to
the callback pointer. This turned out to be suboptimal for the upcoming
Rust integration and is obviously a silly implementation to begin with.
This cleanup replaces the hrtimer_init(T); T->function = cb; sequence
with hrtimer_setup(T, cb);
The conversion was done with Coccinelle and a few manual fixups.
Once the conversion has completely landed in mainline, hrtimer_init()
will be removed and the hrtimer::function becomes a private member.
-----BEGIN PGP SIGNATURE-----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=bYAX
-----END PGP SIGNATURE-----
Merge tag 'timers-cleanups-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer cleanups from Thomas Gleixner:
"A treewide hrtimer timer cleanup
hrtimers are initialized with hrtimer_init() and a subsequent store to
the callback pointer. This turned out to be suboptimal for the
upcoming Rust integration and is obviously a silly implementation to
begin with.
This cleanup replaces the hrtimer_init(T); T->function = cb; sequence
with hrtimer_setup(T, cb);
The conversion was done with Coccinelle and a few manual fixups.
Once the conversion has completely landed in mainline, hrtimer_init()
will be removed and the hrtimer::function becomes a private member"
* tag 'timers-cleanups-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits)
wifi: rt2x00: Switch to use hrtimer_update_function()
io_uring: Use helper function hrtimer_update_function()
serial: xilinx_uartps: Use helper function hrtimer_update_function()
ASoC: fsl: imx-pcm-fiq: Switch to use hrtimer_setup()
RDMA: Switch to use hrtimer_setup()
virtio: mem: Switch to use hrtimer_setup()
drm/vmwgfx: Switch to use hrtimer_setup()
drm/xe/oa: Switch to use hrtimer_setup()
drm/vkms: Switch to use hrtimer_setup()
drm/msm: Switch to use hrtimer_setup()
drm/i915/request: Switch to use hrtimer_setup()
drm/i915/uncore: Switch to use hrtimer_setup()
drm/i915/pmu: Switch to use hrtimer_setup()
drm/i915/perf: Switch to use hrtimer_setup()
drm/i915/gvt: Switch to use hrtimer_setup()
drm/i915/huc: Switch to use hrtimer_setup()
drm/amdgpu: Switch to use hrtimer_setup()
stm class: heartbeat: Switch to use hrtimer_setup()
i2c: Switch to use hrtimer_setup()
iio: Switch to use hrtimer_setup()
...
[ Merge note, these two commits are identical:
- f3fa0e40df ("sched/clock: Don't define sched_clock_irqtime as static key")
- b9f2b29b94 ("sched: Don't define sched_clock_irqtime as static key")
The first one is a cherry-picked version of the second, and the first one
is already upstream. ]
Core & fair scheduler changes:
- Cancel the slice protection of the idle entity (Zihan Zhou)
- Reduce the default slice to avoid tasks getting an extra tick
(Zihan Zhou)
- Force propagating min_slice of cfs_rq when {en,de}queue tasks
(Tianchen Ding)
- Refactor can_migrate_task() to elimate looping (I Hsin Cheng)
- Add unlikey branch hints to several system calls (Colin Ian King)
- Optimize current_clr_polling() on certain architectures (Yujun Dong)
Deadline scheduler: (Juri Lelli)
- Remove redundant dl_clear_root_domain call
- Move dl_rebuild_rd_accounting to cpuset.h
Uclamp:
- Use the uclamp_is_used() helper instead of open-coding it (Xuewen Yan)
- Optimize sched_uclamp_used static key enabling (Xuewen Yan)
Scheduler topology support: (Juri Lelli)
- Ignore special tasks when rebuilding domains
- Add wrappers for sched_domains_mutex
- Generalize unique visiting of root domains
- Rebuild root domain accounting after every update
- Remove partition_and_rebuild_sched_domains
- Stop exposing partition_sched_domains_locked
RSEQ: (Michael Jeanson)
- Update kernel fields in lockstep with CONFIG_DEBUG_RSEQ=y
- Fix segfault on registration when rseq_cs is non-zero
- selftests: Add rseq syscall errors test
- selftests: Ensure the rseq ABI TLS is actually 1024 bytes
Membarriers:
- Fix redundant load of membarrier_state (Nysal Jan K.A.)
Scheduler debugging:
- Introduce and use preempt_model_str() (Sebastian Andrzej Siewior)
- Make CONFIG_SCHED_DEBUG unconditional (Ingo Molnar)
Fixes and cleanups:
- Always save/restore x86 TSC sched_clock() on suspend/resume
(Guilherme G. Piccoli)
- Misc fixes and cleanups (Thorsten Blum, Juri Lelli,
Sebastian Andrzej Siewior)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----
iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmfejsoRHG1pbmdvQGtl
cm5lbC5vcmcACgkQEnMQ0APhK1ivkhAAwBF2tYRBS1oIHcC/OKK3JJoHVDp2LFbU
9sm5S3ZlGD/Ns2fbpY+9A8UFgUFfjYiTSV7hvf2B9Vge0XSxTmMNFu/MdxLBbo9r
w6GSeNcNDQKpjEGLkrmPFsa2fiYI4dmH0IzDbS9V2cNPk470QBKjAKXNPaSER691
n2wLnQq+m5o4gXnPjnSz6RrrzisRnm2GOWnDV/iqR47pZFNlX2wWlo3s5r7//Hw0
a+QfEfpgKehhy/VSDXmSAgpqnNffjc78yBV6LNoVUddwahnOWiQMS3XViOqgy5VO
jUGBrzW+sKkdRMBppxwJ/0XWgHGC27amIgnU0ZE5u+eiUEu8H9qWl1cRCFxyeB0O
8+WNfwmkH+FPWUdsn84kdePhSsZy6HfM6h44Xe0hx1V7tQXEXfbPzK3TnQg8Ktt1
Ky6ctbZt4cGpqGQuIqvba21A/racrD/DgvB7mHeZksnqZoKTDwxhT/nlQGpuwPoy
SJYd1ynFVJvfC69SwMdwnaglimvEZx1GfT0o5XtCMslY5NkWCou5u+e65WX7ccU5
94wBCwI1/+KiFMJZp6TlPw07Q/Hsj9dDryxLc3OunU3zMVt3++1GZnBS/eb5FN1A
5TlAEpxgH9c5Q4/XJFCvx21DrTVHSuIrR6naK91bgqHo0cEfaHGtO/ejPtJGSfxe
YIFnnu1dhRw=
=SuQE
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core & fair scheduler changes:
- Cancel the slice protection of the idle entity (Zihan Zhou)
- Reduce the default slice to avoid tasks getting an extra tick
(Zihan Zhou)
- Force propagating min_slice of cfs_rq when {en,de}queue tasks
(Tianchen Ding)
- Refactor can_migrate_task() to elimate looping (I Hsin Cheng)
- Add unlikey branch hints to several system calls (Colin Ian King)
- Optimize current_clr_polling() on certain architectures (Yujun
Dong)
Deadline scheduler: (Juri Lelli)
- Remove redundant dl_clear_root_domain call
- Move dl_rebuild_rd_accounting to cpuset.h
Uclamp:
- Use the uclamp_is_used() helper instead of open-coding it (Xuewen
Yan)
- Optimize sched_uclamp_used static key enabling (Xuewen Yan)
Scheduler topology support: (Juri Lelli)
- Ignore special tasks when rebuilding domains
- Add wrappers for sched_domains_mutex
- Generalize unique visiting of root domains
- Rebuild root domain accounting after every update
- Remove partition_and_rebuild_sched_domains
- Stop exposing partition_sched_domains_locked
RSEQ: (Michael Jeanson)
- Update kernel fields in lockstep with CONFIG_DEBUG_RSEQ=y
- Fix segfault on registration when rseq_cs is non-zero
- selftests: Add rseq syscall errors test
- selftests: Ensure the rseq ABI TLS is actually 1024 bytes
Membarriers:
- Fix redundant load of membarrier_state (Nysal Jan K.A.)
Scheduler debugging:
- Introduce and use preempt_model_str() (Sebastian Andrzej Siewior)
- Make CONFIG_SCHED_DEBUG unconditional (Ingo Molnar)
Fixes and cleanups:
- Always save/restore x86 TSC sched_clock() on suspend/resume
(Guilherme G. Piccoli)
- Misc fixes and cleanups (Thorsten Blum, Juri Lelli, Sebastian
Andrzej Siewior)"
* tag 'sched-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
cpuidle, sched: Use smp_mb__after_atomic() in current_clr_polling()
sched/debug: Remove CONFIG_SCHED_DEBUG
sched/debug: Remove CONFIG_SCHED_DEBUG from self-test config files
sched/debug, Documentation: Remove (most) CONFIG_SCHED_DEBUG references from documentation
sched/debug: Make CONFIG_SCHED_DEBUG functionality unconditional
sched/debug: Make 'const_debug' tunables unconditional __read_mostly
sched/debug: Change SCHED_WARN_ON() to WARN_ON_ONCE()
rseq/selftests: Fix namespace collision with rseq UAPI header
include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h
sched/topology: Stop exposing partition_sched_domains_locked
cgroup/cpuset: Remove partition_and_rebuild_sched_domains
sched/topology: Remove redundant dl_clear_root_domain call
sched/deadline: Rebuild root domain accounting after every update
sched/deadline: Generalize unique visiting of root domains
sched/topology: Wrappers for sched_domains_mutex
sched/deadline: Ignore special tasks when rebuilding domains
tracing: Use preempt_model_str()
xtensa: Rely on generic printing of preemption model
x86: Rely on generic printing of preemption model
s390: Rely on generic printing of preemption model
...
- The biggest change is the new option to automatically fail
the build on objtool warnings: CONFIG_OBJTOOL_WERROR.
While there are no currently known unfixed false positives
left, such an expansion in the severity of objtool warnings
inevitably creates a risk of build failures, so it's disabled by
default and depends on !COMPILE_TEST, so it shouldn't be enabled
on allyesconfig/allmodconfig builds and won't be forced on people
who just accept build-time defaults in 'make oldconfig'.
While the option is strongly recommended, only people who enable
it explicitly should see it.
(Josh Poimboeuf)
- Disable branch profiling in noinstr code with a broad
brush that includes all of arch/x86/ and kernel/sched/. (Josh Poimboeuf)
- Create backup object files on objtool errors and print exact
objtool arguments to make failure analysis easier (Josh Poimboeuf)
- Improve noreturn handling (Josh Poimboeuf)
- Improve rodata handling (Tiezhu Yang)
- Support jump tables, switch tables and goto tables on LoongArch (Tiezhu Yang)
- Misc cleanups and fixes (Josh Poimboeuf, David Engraf, Ingo Molnar)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----
iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmfefkARHG1pbmdvQGtl
cm5lbC5vcmcACgkQEnMQ0APhK1inlRAAvd9Hom2qh9Iu+KYYF58vsg9zsxWZA6I1
blouKI4SUA8Xjuw6Nihx+emaPaMW1boGSLTNsFzrCa3S1+4UHTTp/Y8snZWJ/Mc/
Peg52N6u/LIcoQM+vNJYRtd9y4wabX87vl0qTxte0kB0Neps3/yQvxtUa2K1srXp
8nwHK+PdzNsgPuIrIiNc9ymsPvbqFHmVIRRVNVKX4BlPJi2kJs9kx43kszweQR/X
kW/bs1315m1HS5i02K0Zs/XdOZHLsk9ERu+aviBJV1txrgZIukATIqbODiI+3RZX
0oa3KxfzEVFN2k3OukrezV2INzETkN+oOSTAZIUOqwSVe+8rdQVBSdYT6svYn/yy
aS8Bi5Mm1nfizTU+cRrzU7FxWCmwsxm9r4fHPTV8Owjxg0uoGk/E/qlvERuR2rpA
p2tHMo1lp2Yo+VZBZPfm5KDHFG4tSGhF9eav2bqSI7/Kf5AWxRl8kBs5iLrcxsXh
4qk3FalnuM7A+1McAUcBJAvM897Yie0s2G83ZipyYyA6U3LSBhBMWh9FlIiAjuIh
YnX6IFkW9tVzVZpJFEGQn+2Ewl5Y2Go5bokKk03vkWCZCgg+hEUsVh6Cnm1ocZpO
Ll3/UF4i8XjjyuAuHDn6mzyHIgch2xRN02v7dJSb09+O9b8vIoPoSqbWSLJUOBqf
r6UesXDG8mY=
=iswJ
-----END PGP SIGNATURE-----
Merge tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- The biggest change is the new option to automatically fail the build
on objtool warnings: CONFIG_OBJTOOL_WERROR.
While there are no currently known unfixed false positives left, such
an expansion in the severity of objtool warnings inevitably creates a
risk of build failures, so it's disabled by default and depends on
!COMPILE_TEST, so it shouldn't be enabled on
allyesconfig/allmodconfig builds and won't be forced on people who
just accept build-time defaults in 'make oldconfig'.
While the option is strongly recommended, only people who enable it
explicitly should see it.
(Josh Poimboeuf)
- Disable branch profiling in noinstr code with a broad brush that
includes all of arch/x86/ and kernel/sched/. (Josh Poimboeuf)
- Create backup object files on objtool errors and print exact objtool
arguments to make failure analysis easier (Josh Poimboeuf)
- Improve noreturn handling (Josh Poimboeuf)
- Improve rodata handling (Tiezhu Yang)
- Support jump tables, switch tables and goto tables on LoongArch
(Tiezhu Yang)
- Misc cleanups and fixes (Josh Poimboeuf, David Engraf, Ingo Molnar)
* tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
tracing: Disable branch profiling in noinstr code
objtool: Use O_CREAT with explicit mode mask
objtool: Add CONFIG_OBJTOOL_WERROR
objtool: Create backup on error and print args
objtool: Change "warning:" to "error:" for --Werror
objtool: Add --Werror option
objtool: Add --output option
objtool: Upgrade "Linked object detected" warning to error
objtool: Consolidate option validation
objtool: Remove --unret dependency on --rethunk
objtool: Increase per-function WARN_FUNC() rate limit
objtool: Update documentation
objtool: Improve __noreturn annotation warning
objtool: Fix error handling inconsistencies in check()
x86/traps: Make exc_double_fault() consistently noreturn
LoongArch: Enable jump table for objtool
objtool/LoongArch: Add support for goto table
objtool/LoongArch: Add support for switch table
objtool: Handle PC relative relocation type
objtool: Handle different entry size of rodata
...
This pull request contains the following branches:
docs.2025.02.04a:
- Add broken-timing possibility to stallwarn.rst.
- Improve discussion of this_cpu_ptr(), add raw_cpu_ptr().
- Document self-propagating callbacks.
- Point call_srcu() to call_rcu() for detailed memory ordering.
- Add CONFIG_RCU_LAZY delays to call_rcu() kernel-doc header.
- Clarify RCU_LAZY and RCU_LAZY_DEFAULT_OFF help text.
- Remove references to old grace-period-wait primitives.
srcu.2025.02.05a:
- Introduce srcu_read_{un,}lock_fast(), which is similar to
srcu_read_{un,}lock_lite(): avoid smp_mb()s in lock and unlock at the
cost of calling synchronize_rcu() in synchronize_srcu(). Moreover, by
returning the percpu offset of the counter at srcu_read_lock_fast()
time, srcu_read_unlock_fast() can save extra pointer dereferencing,
which makes it faster than srcu_read_{un,}lock_lite().
srcu_read_{un,}lock_fast() are intended to replace
rcu_read_{un,}lock_trace() if possible.
torture.2025.02.05a:
- Add get_torture_init_jiffies() to return the start time of the test.
- Add a test_boost_holdoff module parameter to allow delaying boosting
tests when building rcutorture as built-in.
- Add grace period sequence number logging at the beginning and end of
failure/close-call results.
- Switch to hexadecimal for the expedited grace period sequence number
in the rcu_exp_grace_period trace point.
- Make cur_ops->format_gp_seqs take buffer length.
- Move RCU_TORTURE_TEST_{CHK_RDR_STATE,LOG_CPU} to bool.
- Complain when invalid SRCU reader_flavor is specified.
- Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing, which forces SRCU
uses atomics even when percpu ops are NMI safe, and use the Kconfig
for SRCU lockdep testing.
misc.2025.03.04a:
- Split rcu_report_exp_cpu_mult() mask parameter and use for tracing.
- Remove READ_ONCE() for rdp->gpwrap access in __note_gp_changes().
- Fix get_state_synchronize_rcu_full() GP-start detection.
- Move RCU Tasks self-tests to core_initcall().
- Print segment lengths in show_rcu_nocb_gp_state().
- Make RCU watch ct_kernel_exit_state() warning.
- Flush console log from kernel_power_off().
- rcutorture: Allow a negative value for nfakewriters.
- rcu: Update TREE05.boot to test normal synchronize_rcu().
- rcu: Use _full() API to debug synchronize_rcu().
lazypreempt.2025.03.04a: Make RCU handle PREEMPT_LAZY better:
- Fix header guard for rcu_all_qs().
- rcu: Rename PREEMPT_AUTO to PREEMPT_LAZY.
- Update __cond_resched comment about RCU quiescent states.
- Handle unstable rdp in rcu_read_unlock_strict().
- Handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y.
- osnoise: Provide quiescent states.
- Adjust rcutorture with possible PREEMPT_RCU=n && PREEMPT_COUNT=y
combination.
- Limit PREEMPT_RCU configurations.
- Make rcutorture senario TREE07 and senario TREE10 use PREEMPT_LAZY=y.
-----BEGIN PGP SIGNATURE-----
iQEzBAABCAAdFiEEj5IosQTPz8XU1wRHSXnow7UH+rgFAmfeBLQACgkQSXnow7UH
+rh11Qf/Rt6IZJ/YT/V9Sd+8hMx4O0BMh779pr9cD6mbAG+FDk2Yeva1m8vIdFOb
qId6oc8K/ef2JfFjSn0oHMzQP2D3XUyiJWPNbBDHv/D8Os8GZgjzu8dkxVkSbdbY
OxtvIflbcqFN1JDJfGKZnTEW0/YxGqfnS9b6R7iyyA7SOGQ/WubGOE5qNCqPufc9
zJiP+qTUFYQzCIiPlEJul39o9KboPogbt3QAAQjWmi3utd77ehJnm/15FvAjyau4
uhC2cnGfMY535rQaiaQeBQ/IHIowKripCq0JQFvcUNdyArZM3HOI2x79+2II6ft7
mjHskNODOIJHfW2o1RzQ0yRYAywFIg==
=J+mH
-----END PGP SIGNATURE-----
Merge tag 'rcu-next-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU updates from Boqun Feng:
"Documentation:
- Add broken-timing possibility to stallwarn.rst
- Improve discussion of this_cpu_ptr(), add raw_cpu_ptr()
- Document self-propagating callbacks
- Point call_srcu() to call_rcu() for detailed memory ordering
- Add CONFIG_RCU_LAZY delays to call_rcu() kernel-doc header
- Clarify RCU_LAZY and RCU_LAZY_DEFAULT_OFF help text
- Remove references to old grace-period-wait primitives
srcu:
- Introduce srcu_read_{un,}lock_fast(), which is similar to
srcu_read_{un,}lock_lite(): avoid smp_mb()s in lock and unlock
at the cost of calling synchronize_rcu() in synchronize_srcu()
Moreover, by returning the percpu offset of the counter at
srcu_read_lock_fast() time, srcu_read_unlock_fast() can avoid
extra pointer dereferencing, which makes it faster than
srcu_read_{un,}lock_lite()
srcu_read_{un,}lock_fast() are intended to replace
rcu_read_{un,}lock_trace() if possible
RCU torture:
- Add get_torture_init_jiffies() to return the start time of the test
- Add a test_boost_holdoff module parameter to allow delaying
boosting tests when building rcutorture as built-in
- Add grace period sequence number logging at the beginning and end
of failure/close-call results
- Switch to hexadecimal for the expedited grace period sequence
number in the rcu_exp_grace_period trace point
- Make cur_ops->format_gp_seqs take buffer length
- Move RCU_TORTURE_TEST_{CHK_RDR_STATE,LOG_CPU} to bool
- Complain when invalid SRCU reader_flavor is specified
- Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing, which forces SRCU
uses atomics even when percpu ops are NMI safe, and use the Kconfig
for SRCU lockdep testing
Misc:
- Split rcu_report_exp_cpu_mult() mask parameter and use for tracing
- Remove READ_ONCE() for rdp->gpwrap access in __note_gp_changes()
- Fix get_state_synchronize_rcu_full() GP-start detection
- Move RCU Tasks self-tests to core_initcall()
- Print segment lengths in show_rcu_nocb_gp_state()
- Make RCU watch ct_kernel_exit_state() warning
- Flush console log from kernel_power_off()
- rcutorture: Allow a negative value for nfakewriters
- rcu: Update TREE05.boot to test normal synchronize_rcu()
- rcu: Use _full() API to debug synchronize_rcu()
Make RCU handle PREEMPT_LAZY better:
- Fix header guard for rcu_all_qs()
- rcu: Rename PREEMPT_AUTO to PREEMPT_LAZY
- Update __cond_resched comment about RCU quiescent states
- Handle unstable rdp in rcu_read_unlock_strict()
- Handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y
- osnoise: Provide quiescent states
- Adjust rcutorture with possible PREEMPT_RCU=n && PREEMPT_COUNT=y
combination
- Limit PREEMPT_RCU configurations
- Make rcutorture senario TREE07 and senario TREE10 use
PREEMPT_LAZY=y"
* tag 'rcu-next-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits)
rcutorture: Make scenario TREE07 build CONFIG_PREEMPT_LAZY=y
rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y
rcu: limit PREEMPT_RCU configurations
rcutorture: Update ->extendables check for lazy preemption
rcutorture: Update rcutorture_one_extend_check() for lazy preemption
osnoise: provide quiescent states
rcu: Use _full() API to debug synchronize_rcu()
rcu: Update TREE05.boot to test normal synchronize_rcu()
rcutorture: Allow a negative value for nfakewriters
Flush console log from kernel_power_off()
context_tracking: Make RCU watch ct_kernel_exit_state() warning
rcu/nocb: Print segment lengths in show_rcu_nocb_gp_state()
rcu-tasks: Move RCU Tasks self-tests to core_initcall()
rcu: Fix get_state_synchronize_rcu_full() GP-start detection
torture: Make SRCU lockdep testing use srcu_read_lock_nmisafe()
srcu: Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing
rcutorture: Complain when invalid SRCU reader_flavor is specified
rcutorture: Move RCU_TORTURE_TEST_{CHK_RDR_STATE,LOG_CPU} to bool
rcutorture: Make cur_ops->format_gp_seqs take buffer length
rcutorture: Add ftrace-compatible timestamp to GP# failure/close-call output
...
- Add mechanism to count and report internal events. This significantly
improves visibility on subtle corner conditions.
- The default idle CPU selection logic is revamped and improved in multiple
ways including being made topology aware.
- sched_ext was disabling ttwu_queue for simplicity, which can be costly
when hardware topology is more complex. Implement
SCX_OPS_ALLOWED_QUEUED_WAKEUP so that BPF schedulers can selectively
enable ttwu_queue.
- tools/sched_ext updates to improve compatibility among others.
- Other misc updates and fixes.
- sched_ext/for-6.14-fixes were pulled a few times to receive prerequisite
fixes and resolve conflicts.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCZ999Sg4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGf/KAQCoMTVOBpQT9gCaCKDOmrVJTwi6boEoV5WnGZzw
PDr0vwEAq36iz4no6Y5THcN/DCx+52IiS0zuhPy3rBZVo11TMgU=
=iQ+A
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- Add mechanism to count and report internal events. This significantly
improves visibility on subtle corner conditions.
- The default idle CPU selection logic is revamped and improved in
multiple ways including being made topology aware.
- sched_ext was disabling ttwu_queue for simplicity, which can be
costly when hardware topology is more complex. Implement
SCX_OPS_ALLOWED_QUEUED_WAKEUP so that BPF schedulers can selectively
enable ttwu_queue.
- tools/sched_ext updates to improve compatibility among others.
- Other misc updates and fixes.
- sched_ext/for-6.14-fixes were pulled a few times to receive
prerequisite fixes and resolve conflicts.
* tag 'sched_ext-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (42 commits)
sched_ext: idle: Refactor scx_select_cpu_dfl()
sched_ext: idle: Honor idle flags in the built-in idle selection policy
sched_ext: Skip per-CPU tasks in scx_bpf_reenqueue_local()
sched_ext: Add trace point to track sched_ext core events
sched_ext: Change the event type from u64 to s64
sched_ext: Documentation: add task lifecycle summary
tools/sched_ext: Provide a compatible helper for scx_bpf_events()
selftests/sched_ext: Add NUMA-aware scheduler test
tools/sched_ext: Provide consistent access to scx flags
sched_ext: idle: Fix scx_bpf_pick_any_cpu_node() behavior
sched_ext: idle: Introduce scx_bpf_nr_node_ids()
sched_ext: idle: Introduce node-aware idle cpu kfunc helpers
sched_ext: idle: Per-node idle cpumasks
sched_ext: idle: Introduce SCX_OPS_BUILTIN_IDLE_PER_NODE
sched_ext: idle: Make idle static keys private
sched/topology: Introduce for_each_node_numadist() iterator
mm/numa: Introduce nearest_node_nodemask()
nodemask: numa: reorganize inclusion path
nodemask: add nodes_copy()
tools/sched_ext: Sync with scx repo
...
Add the following tracepoints:
* sched_entry(bool preempt, ip)
Called while entering __schedule
* sched_exit(bool is_switch, ip)
Called while exiting __schedule
* sched_set_state(task, curr_state, state)
Called when a task changes its state (to and from running)
These tracepoints are useful to describe the Linux task model and are
adapted from the patches by Daniel Bristot de Oliveira
(https://bristot.me/linux-task-model/).
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/20250305140406.350227-2-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
CONFIG_TRACE_BRANCH_PROFILING inserts a call to ftrace_likely_update()
for each use of likely() or unlikely(). That breaks noinstr rules if
the affected function is annotated as noinstr.
Disable branch profiling for files with noinstr functions. In addition
to some individual files, this also includes the entire arch/x86
subtree, as well as the kernel/entry, drivers/cpuidle, and drivers/idle
directories, all of which are noinstr-heavy.
Due to the nature of how sched binaries are built by combining multiple
.c files into one, branch profiling is disabled more broadly across the
sched code than would otherwise be needed.
This fixes many warnings like the following:
vmlinux.o: warning: objtool: do_syscall_64+0x40: call to ftrace_likely_update() leaves .noinstr.text section
vmlinux.o: warning: objtool: __rdgsbase_inactive+0x33: call to ftrace_likely_update() leaves .noinstr.text section
vmlinux.o: warning: objtool: handle_bug.isra.0+0x198: call to ftrace_likely_update() leaves .noinstr.text section
...
Reported-by: Ingo Molnar <mingo@kernel.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/fb94fc9303d48a5ed370498f54500cc4c338eb6d.1742586676.git.jpoimboe@kernel.org
All the big Linux distros enable CONFIG_SCHED_DEBUG, because
the various features it provides help not just with kernel
development, but with system administration and user-space
software development as well.
Reflect this reality and enable this functionality
unconditionally.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-4-mingo@kernel.org
The scheduler has this special SCHED_WARN() facility that
depends on CONFIG_SCHED_DEBUG.
Since CONFIG_SCHED_DEBUG is getting removed, convert
SCHED_WARN() to WARN_ON_ONCE().
Note that the warning output isn't 100% equivalent:
#define SCHED_WARN_ON(x) WARN_ONCE(x, #x)
Because SCHED_WARN_ON() would output the 'x' condition
as well, while WARN_ONCE() will only show a backtrace.
Hopefully these are rare enough to not really matter.
If it does, we should probably introduce a new WARN_ON()
variant that outputs the condition in stringified form,
or improve WARN_ON() itself.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-2-mingo@kernel.org
The are no callers of partition_sched_domains_locked() outside
topology.c.
Stop exposing such function.
Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MSC96a8FcqWV3G@jlelli-thinkpadt14gen4.remote.csb
We completely clean and restore root domains bandwidth accounting after
every root domains change, so the dl_clear_root_domain() call in
partition_sched_domains_locked() is redundant.
Remove it.
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <llong@redhat.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MRtcX4tz4tcLRR@jlelli-thinkpadt14gen4.remote.csb
Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
is that the way we keep track of domain changes and try to add bandwidth
back is convoluted and fragile.
Fix it by simplify things by making sure bandwidth accounting is cleared
and completely restored after root domains changes (after root domains
are again stable).
To be sure we always call dl_rebuild_rd_accounting while holding
cpuset_mutex we also add cpuset_reset_sched_domains() wrapper.
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Co-developed-by: Waiman Long <llong@redhat.com>
Signed-off-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MRfeJKJUOyUSto@jlelli-thinkpadt14gen4.remote.csb
Bandwidth checks and updates that work on root domains currently employ
a cookie mechanism for efficiency. This mechanism is very much tied to
when root domains are first created and initialized.
Generalize the cookie mechanism so that it can be used also later at
runtime while updating root domains. Also, additionally guard it with
sched_domains_mutex, since domains need to be stable while updating them
(and it will be required for further dynamic changes).
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MQaiXPvEeW_v7x@jlelli-thinkpadt14gen4.remote.csb
Create wrappers for sched_domains_mutex so that it can transparently be
used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
do.
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MP5Oq9RB8jBs3y@jlelli-thinkpadt14gen4.remote.csb
SCHED_DEADLINE special tasks get a fake bandwidth that is only used to
make sure sleeping and priority inheritance 'work', but it is ignored
for runtime enforcement and admission control.
Be consistent with it also when rebuilding root domains.
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20250313170011.357208-2-juri.lelli@redhat.com
The individual architectures often add the preemption model to the begin
of the backtrace. This is the case on X86 or ARM64 for the "die" case
but not for regular warning. With the addition of DYNAMIC_PREEMPT for
PREEMPT_RT we end up with CONFIG_PREEMPT and CONFIG_PREEMPT_RT set
simultaneously. That means that everyone who tried to add that piece of
information gets it wrong for PREEMPT_RT because PREEMPT is checked
first.
Provide a generic function which returns the current scheduling model
considering LAZY preempt and the current state of PREEMPT_DYNAMIC.
The resulting strings are:
┏━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓
┃ Model ┃ -RT -DYN ┃ +RT -DYN ┃ -RT +DYN ┃ +RT +DYN ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩
│NONE │ NONE │ n/a │ PREEMPT(none) │ n/a │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│VOLUNTARY │ VOLUNTARY │ n/a │ PREEMPT(voluntary) │ n/a │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│FULL │ PREEMPT │ PREEMPT_RT │ PREEMPT(full) │ PREEMPT_{RT,full} │
├───────────┼──────────────┼───────────────────┼────────────────────┼───────────────────┤
│LAZY │ PREEMPT_LAZY │ PREEMPT_{RT,LAZY} │ PREEMPT(lazy) │ PREEMPT_{RT,lazy} │
└───────────┴──────────────┴───────────────────┴────────────────────┴───────────────────┘
[ The dynamic building of the string can lead to an empty string if the
function is invoked simultaneously on two CPUs. ]
Co-developed-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Co-developed-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Signed-off-by: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20250314160810.2373416-2-bigeasy@linutronix.de
This reverts commit eff6c8ce8d.
Hazem reported a 30% drop in UnixBench spawn test with commit
eff6c8ce8d ("sched/core: Reduce cost of sched_move_task when config
autogroup") on a m6g.xlarge AWS EC2 instance with 4 vCPUs and 16 GiB RAM
(aarch64) (single level MC sched domain):
https://lkml.kernel.org/r/20250205151026.13061-1-hagarhem@amazon.com
There is an early bail from sched_move_task() if p->sched_task_group is
equal to p's 'cpu cgroup' (sched_get_task_group()). E.g. both are
pointing to taskgroup '/user.slice/user-1000.slice/session-1.scope'
(Ubuntu '22.04.5 LTS').
So in:
do_exit()
sched_autogroup_exit_task()
sched_move_task()
if sched_get_task_group(p) == p->sched_task_group
return
/* p is enqueued */
dequeue_task() \
sched_change_group() |
task_change_group_fair() |
detach_task_cfs_rq() | (1)
set_task_rq() |
attach_task_cfs_rq() |
enqueue_task() /
(1) isn't called for p anymore.
Turns out that the regression is related to sgs->group_util in
group_is_overloaded() and group_has_capacity(). If (1) isn't called for
all the 'spawn' tasks then sgs->group_util is ~900 and
sgs->group_capacity = 1024 (single CPU sched domain) and this leads to
group_is_overloaded() returning true (2) and group_has_capacity() false
(3) much more often compared to the case when (1) is called.
I.e. there are much more cases of 'group_is_overloaded' and
'group_fully_busy' in WF_FORK wakeup sched_balance_find_dst_cpu() which
then returns much more often a CPU != smp_processor_id() (5).
This isn't good for these extremely short running tasks (FORK + EXIT)
and also involves calling sched_balance_find_dst_group_cpu() unnecessary
(single CPU sched domain).
Instead if (1) is called for 'p->flags & PF_EXITING' then the path
(4),(6) is taken much more often.
select_task_rq_fair(..., wake_flags = WF_FORK)
cpu = smp_processor_id()
new_cpu = sched_balance_find_dst_cpu(..., cpu, ...)
group = sched_balance_find_dst_group(..., cpu)
do {
update_sg_wakeup_stats()
sgs->group_type = group_classify()
if group_is_overloaded() (2)
return group_overloaded
if !group_has_capacity() (3)
return group_fully_busy
return group_has_spare (4)
} while group
if local_sgs.group_type > idlest_sgs.group_type
return idlest (5)
case group_has_spare:
if local_sgs.idle_cpus >= idlest_sgs.idle_cpus
return NULL (6)
Unixbench Tests './Run -c 4 spawn' on:
(a) VM AWS instance (m7gd.16xlarge) with v6.13 ('maxcpus=4 nr_cpus=4')
and Ubuntu 22.04.5 LTS (aarch64).
Shell & test run in '/user.slice/user-1000.slice/session-1.scope'.
w/o patch w/ patch
21005 27120
(b) i7-13700K with tip/sched/core ('nosmt maxcpus=8 nr_cpus=8') and
Ubuntu 22.04.5 LTS (x86_64).
Shell & test run in '/A'.
w/o patch w/ patch
67675 88806
CONFIG_SCHED_AUTOGROUP=y & /sys/proc/kernel/sched_autogroup_enabled equal
0 or 1.
Reported-by: Hazem Mohamed Abuelfotoh <abuehaze@amazon.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Hagar Hemdan <hagarhem@amazon.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250314151345.275739-1-dietmar.eggemann@arm.com
Repeat calls of static_branch_enable() to an already enabled
static key introduce overhead, because it calls cpus_read_lock().
Users may frequently set the uclamp value of tasks, triggering
the repeat enabling of the sched_uclamp_used static key.
Optimize this and avoid repeat calls to static_branch_enable()
by checking whether it's enabled already.
[ mingo: Rewrote the changelog for legibility ]
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250219093747.2612-2-xuewen.yan@unisoc.com
Don't open-code static_branch_unlikely(&sched_uclamp_used), we have
the uclamp_is_used() wrapper around it.
[ mingo: Clean up the changelog ]
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250219093747.2612-1-xuewen.yan@unisoc.com
utilizing static keys that didn't consider that the
static_key_disable() call could be triggered in atomic context.
Revert the optimization.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=fXc6
-----END PGP SIGNATURE-----
Merge tag 'sched-urgent-2025-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"Fix a sleeping-while-atomic bug caused by a recent optimization
utilizing static keys that didn't consider that the
static_key_disable() call could be triggered in atomic context.
Revert the optimization"
* tag 'sched-urgent-2025-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/clock: Don't define sched_clock_irqtime as static key
Make scx_select_cpu_dfl() more consistent with the other idle-related
APIs by returning a negative value when an idle CPU isn't found.
No functional changes, this is purely a refactoring.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Enable passing idle flags (%SCX_PICK_IDLE_*) to scx_select_cpu_dfl(),
to enforce strict selection criteria, such as selecting an idle CPU
strictly within @prev_cpu's node or choosing only a fully idle SMT core.
This functionality will be exposed through a dedicated kfunc in a
separate patch.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_bpf_reenqueue_local() can be invoked from ops.cpu_release() to give
tasks that are queued to the local DSQ a chance to migrate to other
CPUs, when a CPU is taken by a higher scheduling class.
However, there is no point re-enqueuing tasks that can only run on that
particular CPU, as they would simply be re-added to the same local DSQ
without any benefit.
Therefore, skip per-CPU tasks in scx_bpf_reenqueue_local().
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
BPF schedulers could trigger a crash by passing in an invalid CPU to the
helper scx_bpf_select_cpu_dfl(). Fix it by verifying input validity.
-----BEGIN PGP SIGNATURE-----
iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCZ9H4tw4cdGpAa2VybmVs
Lm9yZwAKCRCxYfJx3gVYGY2PAP95rqNEACvl5uz/HQM+T0WpwGDaIJ3fmKYd3GZY
3XJjhwD/YmKMLmth0xeDLkAtVUNsMp4EjpssKdzi0CJq+Nl4nQw=
=OxEw
-----END PGP SIGNATURE-----
Merge tag 'sched_ext-for-6.14-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fix from Tejun Heo:
"BPF schedulers could trigger a crash by passing in an invalid CPU to
the scx_bpf_select_cpu_dfl() helper.
Fix it by verifying input validity"
* tag 'sched_ext-for-6.14-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
The sched_clock_irqtime was defined as a static key in:
8722903cbb ("sched: Define sched_clock_irqtime as static key")
However, this change introduces a 'sleeping in atomic context' warning:
arch/x86/kernel/tsc.c:1214 mark_tsc_unstable()
warn: sleeping in atomic context
As analyzed by Dan, the affected code path is as follows:
vcpu_load() <- disables preempt
-> kvm_arch_vcpu_load()
-> mark_tsc_unstable() <- sleeps
virt/kvm/kvm_main.c
166 void vcpu_load(struct kvm_vcpu *vcpu)
167 {
168 int cpu = get_cpu();
^^^^^^^^^^
This get_cpu() disables preemption.
169
170 __this_cpu_write(kvm_running_vcpu, vcpu);
171 preempt_notifier_register(&vcpu->preempt_notifier);
172 kvm_arch_vcpu_load(vcpu, cpu);
173 put_cpu();
174 }
arch/x86/kvm/x86.c
4979 if (unlikely(vcpu->cpu != cpu) || kvm_check_tsc_unstable()) {
4980 s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 :
4981 rdtsc() - vcpu->arch.last_host_tsc;
4982 if (tsc_delta < 0)
4983 mark_tsc_unstable("KVM discovered backwards TSC");
arch/x86/kernel/tsc.c
1206 void mark_tsc_unstable(char *reason)
1207 {
1208 if (tsc_unstable)
1209 return;
1210
1211 tsc_unstable = 1;
1212 if (using_native_sched_clock())
1213 clear_sched_clock_stable();
--> 1214 disable_sched_clock_irqtime();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
kernel/jump_label.c
245 void static_key_disable(struct static_key *key)
246 {
247 cpus_read_lock();
^^^^^^^^^^^^^^^^
This lock has a might_sleep() in it which triggers the static checker
warning.
248 static_key_disable_cpuslocked(key);
249 cpus_read_unlock();
250 }
Let revert this change for now as {disable,enable}_sched_clock_irqtime
are used in many places, as pointed out by Sean, including the following:
The code path in clocksource_watchdog():
clocksource_watchdog()
|
-> spin_lock(&watchdog_lock);
|
-> __clocksource_unstable()
|
-> clocksource.mark_unstable() == tsc_cs_mark_unstable()
|
-> disable_sched_clock_irqtime()
And the code path in sched_clock_register():
/* Cannot register a sched_clock with interrupts on */
local_irq_save(flags);
...
/* Enable IRQ time accounting if we have a fast enough sched_clock() */
if (irqtime > 0 || (irqtime == -1 && rate >= 1000000))
enable_sched_clock_irqtime();
local_irq_restore(flags);
[ lkp@intel.com: reported a build error in the prev version ]
[ mingo: cherry-picked it over into sched/urgent ]
Closes: https://lore.kernel.org/kvm/37a79ba3-9ce0-479c-a5b0-2bd75d573ed3@stanley.mountain/
Fixes: 8722903cbb ("sched: Define sched_clock_irqtime as static key")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Debugged-by: Dan Carpenter <dan.carpenter@linaro.org>
Debugged-by: Sean Christopherson <seanjc@google.com>
Debugged-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20250205032438.14668-1-laoar.shao@gmail.com
