The process of constructing scheduling domains
involves multiple loops and repeated evaluations, leading to numerous
redundant and ineffective assessments that impact code efficiency.
Here, we use union-find to optimize the merging of cpumasks. By employing
path compression and union by rank, we effectively reduce the number of
lookups and merge comparisons.
Signed-off-by: Xavier <xavier_qy@163.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There are several functions to decrease attach_in_progress, and they
will wake up cpuset_attach_wq when attach_in_progress is zero. So,
add a helper to make it concise.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since the SLAB implementation was removed in v6.8, so the
cpuset_slab_spread_rotor is no longer used and can be removed.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The child_ecpus_count variable was previously used to update
sibling cpumask when parent's effective_cpus is updated. However, it became
obsolete after commit e2ffe502ba ("cgroup/cpuset: Add
cpuset.cpus.exclusive for v2"). It should be removed.
tj: Restored {} for style consistency.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
An UAF can happen when /proc/cpuset is read as reported in [1].
This can be reproduced by the following methods:
1.add an mdelay(1000) before acquiring the cgroup_lock In the
cgroup_path_ns function.
2.$cat /proc/<pid>/cpuset repeatly.
3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/
$umount /sys/fs/cgroup/cpuset/ repeatly.
The race that cause this bug can be shown as below:
(umount) | (cat /proc/<pid>/cpuset)
css_release | proc_cpuset_show
css_release_work_fn | css = task_get_css(tsk, cpuset_cgrp_id);
css_free_rwork_fn | cgroup_path_ns(css->cgroup, ...);
cgroup_destroy_root | mutex_lock(&cgroup_mutex);
rebind_subsystems |
cgroup_free_root |
| // cgrp was freed, UAF
| cgroup_path_ns_locked(cgrp,..);
When the cpuset is initialized, the root node top_cpuset.css.cgrp
will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will
allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated
&cgroup_root.cgrp. When the umount operation is executed,
top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp.
The problem is that when rebinding to cgrp_dfl_root, there are cases
where the cgroup_root allocated by setting up the root for cgroup v1
is cached. This could lead to a Use-After-Free (UAF) if it is
subsequently freed. The descendant cgroups of cgroup v1 can only be
freed after the css is released. However, the css of the root will never
be released, yet the cgroup_root should be freed when it is unmounted.
This means that obtaining a reference to the css of the root does
not guarantee that css.cgrp->root will not be freed.
Fix this problem by using rcu_read_lock in proc_cpuset_show().
As cgroup_root is kfree_rcu after commit d23b5c5777
("cgroup: Make operations on the cgroup root_list RCU safe"),
css->cgroup won't be freed during the critical section.
To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to
replace task_get_css with task_css.
[1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd
Fixes: a79a908fd2 ("cgroup: introduce cgroup namespaces")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The "cpuset.cpus.exclusive.effective" value is currently limited to a
subset of its "cpuset.cpus". This makes the exclusive CPUs distribution
hierarchy subsumed within the larger "cpuset.cpus" hierarchy. We have to
decide on what CPUs are used locally and what CPUs can be passed down as
exclusive CPUs down the hierarchy and combine them into "cpuset.cpus".
The advantage of the current scheme is to have only one hierarchy to
worry about. However, it make it harder to use as all the "cpuset.cpus"
values have to be properly set along the way down to the designated remote
partition root. It also makes it more cumbersome to find out what CPUs
can be used locally.
Make creation of remote partition simpler by breaking the
dependency of "cpuset.cpus.exclusive" on "cpuset.cpus" and make
them independent entities. Now we have two separate hierarchies -
one for setting "cpuset.cpus.effective" and the other one for setting
"cpuset.cpus.exclusive.effective". We may not need to set "cpuset.cpus"
when we activate a partition root anymore.
Also update Documentation/admin-guide/cgroup-v2.rst and cpuset.c comment
to document this change.
Suggested-by: Petr Malat <oss@malat.biz>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The CS_CPU_EXCLUSIVE flag is currently set whenever cpuset.cpus.exclusive
is set to make sure that the exclusivity test will be run to ensure its
exclusiveness. At the same time, this flag can be changed whenever the
partition root state is changed. For example, the CS_CPU_EXCLUSIVE flag
will be reset whenever a partition root becomes invalid. This makes
using CS_CPU_EXCLUSIVE to ensure exclusiveness a bit fragile.
The current scheme also makes setting up a cpuset.cpus.exclusive
hierarchy to enable remote partition harder as cpuset.cpus.exclusive
cannot overlap with any cpuset.cpus of sibling cpusets if their
cpuset.cpus.exclusive aren't set.
Solve these issues by deferring the setting of CS_CPU_EXCLUSIVE flag
until the cpuset become a valid partition root while adding new checks
in validate_change() to ensure that cpuset.cpus.exclusive of sibling
cpusets cannot overlap.
An additional check is also added to validate_change() to make sure that
cpuset.cpus of one cpuset cannot be a subset of cpuset.cpus.exclusive
of a sibling cpuset to avoid the problem that none of those CPUs will
be available when these exclusive CPUs are extracted out to a newly
enabled partition root. The Documentation/admin-guide/cgroup-v2.rst
file is updated to document the new constraints.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 181c8e091a ("cgroup/cpuset: Introduce remote partition"),
a remote partition can be created underneath a non-partition root cpuset
as long as its exclusive_cpus are set to distribute exclusive CPUs down
to its children. The generate_sched_domains() function, however, doesn't
take into account this new behavior and hence will fail to create the
sched domain needed for a remote root (non-isolated) partition.
There are two issues related to remote partition support. First of
all, generate_sched_domains() has a fast path that is activated if
root_load_balance is true and top_cpuset.nr_subparts is non-zero. The
later condition isn't quite correct for remote partitions as nr_subparts
just shows the number of local child partitions underneath it. There
can be no local child partition under top_cpuset even if there are
remote partitions further down the hierarchy. Fix that by checking
for subpartitions_cpus which contains exclusive CPUs allocated to both
local and remote partitions.
Secondly, the valid partition check for subtree skipping in the csa[]
generation loop isn't enough as remote partition does not need to
have a partition root parent. Fix this problem by breaking csa[] array
generation loop of generate_sched_domains() into v1 and v2 specific parts
and checking a cpuset's exclusive_cpus before skipping its subtree in
the v2 case.
Also simplify generate_sched_domains() for cgroup v2 as only
non-isolating partition roots should be included in building the cpuset
array and none of the v1 scheduling attributes other than a different
way to create an isolated partition are supported.
Fixes: 181c8e091a ("cgroup/cpuset: Introduce remote partition")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
If only isolated partitions are being created underneath the cgroup root,
there will only be one sched domain with top_cpuset.effective_cpus. We can
skip the unnecessary sched domains scanning code and save some cycles.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In the cpuset_css_online(), clearing the CS_SCHED_LOAD_BALANCE bit
of cs->flags is guarded by callback_lock and cpuset_mutex. There is
no problem with itself, because it is consistent with the description
of there two global lock at the beginning of this file. However, since
the operation of checking, setting and clearing the flag bit is atomic,
protection of callback_lock is unnecessary here, see CS_SPREAD_*. so
to make it more consistent with the other code, move the operation
outside the critical section of callback_lock.
No functional changes intended.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 51ffe41178 ("cpuset: convert away from cftype->read()"),
cpuset_common_file_read() has been renamed.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The struct cpuset is kzalloc'd, all the members are zeroed already,
so don't need nodes_clear() here.
No functional changes intended.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Change relax_domain_level checks so that it would be possible
to include or exclude all domains from newidle balancing.
This matches the behavior described in the documentation:
-1 no request. use system default or follow request of others.
0 no search.
1 search siblings (hyperthreads in a core).
"2" enables levels 0 and 1, level_max excludes the last (level_max)
level, and level_max+1 includes all levels.
Fixes: 1d3504fcf5 ("sched, cpuset: customize sched domains, core")
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/bd6de28e80073c79466ec6401cdeae78f0d4423d.1714488502.git.vitaly@bursov.com
The comment here is outdated and can cause confusion, from the code
perspective, there’s also no need for new comment, so just remove it.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 8996f93fc3 ("cgroup/cpuset: Statically initialize more
members of top_cpuset") uses an incorrect "<" relational operator for
the CS_SCHED_LOAD_BALANCE bit when initializing the top_cpuset. This
results in load_balancing turned off by default in the top cpuset which
is bad for performance.
Fix this by using the BIT() helper macro to set the desired top_cpuset
flags and avoid similar mistake from being made in the future.
Fixes: 8996f93fc3 ("cgroup/cpuset: Statically initialize more members of top_cpuset")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In cpuset_css_online(), CS_SCHED_LOAD_BALANCE will be cleared twice,
the former one in the is_in_v2_mode() case could be removed because
is_in_v2_mode() can be true for cgroup v1 if the "cpuset_v2_mode"
mount option is specified, that balance flag change isn't appropriate
for this particular case.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Initializing top_cpuset.relax_domain_level and setting
CS_SCHED_LOAD_BALANCE to top_cpuset.flags in cpuset_init() could be
completed at the time of top_cpuset definition by compiler.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside
get_online_cpus()"), cpuset hotplug was done asynchronously via a work
function. This is to avoid recursive locking of cgroup_mutex.
Since then, the cgroup locking scheme has changed quite a bit. A
cpuset_mutex was introduced to protect cpuset specific operations.
The cpuset_mutex is then replaced by a cpuset_rwsem. With commit
d74b27d63a ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock
order"), cpu_hotplug_lock is acquired before cpuset_rwsem. Later on,
cpuset_rwsem is reverted back to cpuset_mutex. All these locking changes
allow the hotplug code to call into cpuset core directly.
The following commits were also merged due to the asynchronous nature
of cpuset hotplug processing.
- commit b22afcdf04 ("cpu/hotplug: Cure the cpusets trainwreck")
- commit 50e7663233 ("sched/cpuset/pm: Fix cpuset vs. suspend-resume
bugs")
- commit 28b89b9e6f ("cpuset: handle race between CPU hotplug and
cpuset_hotplug_work")
Clean up all these bandages by making cpuset hotplug
processing synchronous again with the exception that the call to
cgroup_transfer_tasks() to transfer tasks out of an empty cgroup v1
cpuset, if necessary, will still be done via a work function due to the
existing cgroup_mutex -> cpu_hotplug_lock dependency. It is possible
to reverse that dependency, but that will require updating a number of
different cgroup controllers. This special hotplug code path should be
rarely taken anyway.
As all the cpuset states will be updated by the end of the hotplug
operation, we can revert most the above commits except commit
50e7663233 ("sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs")
which is partially reverted. Also removing some cpus_read_lock trylock
attempts in the cpuset partition code as they are no longer necessary
since the cpu_hotplug_lock is now held for the whole duration of the
cpuset hotplug code path.
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A quiet cycle. One trivial doc update patch. Two patches to drop now defunct
memory_spread_slab feature from cgroup1 cpuset.
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Merge tag 'cgroup-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"A quiet cycle. One trivial doc update patch. Two patches to drop the
now defunct memory_spread_slab feature from cgroup1 cpuset"
* tag 'cgroup-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: Mark memory_spread_slab as obsolete
cgroup/cpuset: Remove cpuset_do_slab_mem_spread()
docs: cgroup-v1: add missing code-block tags
The update_cpumask(), checks for newly requested cpumask by calling
validate_change(), which returns an error on passing an invalid set
of cpu(s). Independent of the error returned, update_cpumask() always
returns zero, suppressing the error and returning success to the user
on writing an invalid cpu range for a cpuset. Fix it by returning
retval instead, which is returned by validate_change().
Fixes: 99fe36ba6f ("cgroup/cpuset: Improve temporary cpumasks handling")
Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v6.6+
Signed-off-by: Tejun Heo <tj@kernel.org>
We've removed the SLAB allocator, cpuset_do_slab_mem_spread() and
SLAB_MEM_SPREAD, memory_spread_slab is a no-op now. We can mark
memory_spread_slab as obsolete in case someone still wants to use it after
cpuset_do_slab_mem_spread() removed. For more details, please check [1].
[1] https://lore.kernel.org/lkml/32bc1403-49da-445a-8c00-9686a3b0d6a3@redhat.com/T/#m8e292e21b00f95a4bb8086371fa7387fa4ea8f60
tj: Description and cosmetic updates.
Signed-off-by: Xiongwei Song <xiongwei.song@windriver.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix a possible memory leak in update_exclusive_cpumask() by moving the
alloc_cpumasks() down after the validate_change() check which can fail
and still before the temporary cpumasks are needed.
Fixes: e2ffe502ba ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2")
Reported-and-tested-by: Mirsad Todorovac <mirsad.todorovac@alu.hr>
Closes: https://lore.kernel.org/lkml/14915689-27a3-4cd8-80d2-9c30d0c768b6@alu.unizg.hr
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v6.7+
Here are the set of driver core and kernfs changes for 6.8-rc1. Nothing
major in here this release cycle, just lots of small cleanups and some
tweaks on kernfs that in the very end, got reverted and will come back
in a safer way next release cycle.
Included in here are:
- more driver core 'const' cleanups and fixes
- fw_devlink=rpm is now the default behavior
- kernfs tiny changes to remove some string functions
- cpu handling in the driver core is updated to work better on many
systems that add topologies and cpus after booting
- other minor changes and cleanups
All of the cpu handling patches have been acked by the respective
maintainers and are coming in here in one series. Everything has been
in linux-next for a while with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here are the set of driver core and kernfs changes for 6.8-rc1.
Nothing major in here this release cycle, just lots of small cleanups
and some tweaks on kernfs that in the very end, got reverted and will
come back in a safer way next release cycle.
Included in here are:
- more driver core 'const' cleanups and fixes
- fw_devlink=rpm is now the default behavior
- kernfs tiny changes to remove some string functions
- cpu handling in the driver core is updated to work better on many
systems that add topologies and cpus after booting
- other minor changes and cleanups
All of the cpu handling patches have been acked by the respective
maintainers and are coming in here in one series. Everything has been
in linux-next for a while with no reported issues"
* tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (51 commits)
Revert "kernfs: convert kernfs_idr_lock to an irq safe raw spinlock"
kernfs: convert kernfs_idr_lock to an irq safe raw spinlock
class: fix use-after-free in class_register()
PM: clk: make pm_clk_add_notifier() take a const pointer
EDAC: constantify the struct bus_type usage
kernfs: fix reference to renamed function
driver core: device.h: fix Excess kernel-doc description warning
driver core: class: fix Excess kernel-doc description warning
driver core: mark remaining local bus_type variables as const
driver core: container: make container_subsys const
driver core: bus: constantify subsys_register() calls
driver core: bus: make bus_sort_breadthfirst() take a const pointer
kernfs: d_obtain_alias(NULL) will do the right thing...
driver core: Better advertise dev_err_probe()
kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy()
kernfs: Convert kernfs_name_locked() from strlcpy() to strscpy()
kernfs: Convert kernfs_walk_ns() from strlcpy() to strscpy()
initramfs: Expose retained initrd as sysfs file
fs/kernfs/dir: obey S_ISGID
kernel/cgroup: use kernfs_create_dir_ns()
...
One of the last remaining users of strlcpy() in the kernel is
kernfs_path_from_node_locked(), which passes back the problematic "length
we _would_ have copied" return value to indicate truncation. Convert the
chain of all callers to use the negative return value (some of which
already doing this explicitly). All callers were already also checking
for negative return values, so the risk to missed checks looks very low.
In this analysis, it was found that cgroup1_release_agent() actually
didn't handle the "too large" condition, so this is technically also a
bug fix. :)
Here's the chain of callers, and resolution identifying each one as now
handling the correct return value:
kernfs_path_from_node_locked()
kernfs_path_from_node()
pr_cont_kernfs_path()
returns void
kernfs_path()
sysfs_warn_dup()
return value ignored
cgroup_path()
blkg_path()
bfq_bic_update_cgroup()
return value ignored
TRACE_IOCG_PATH()
return value ignored
TRACE_CGROUP_PATH()
return value ignored
perf_event_cgroup()
return value ignored
task_group_path()
return value ignored
damon_sysfs_memcg_path_eq()
return value ignored
get_mm_memcg_path()
return value ignored
lru_gen_seq_show()
return value ignored
cgroup_path_from_kernfs_id()
return value ignored
cgroup_show_path()
already converted "too large" error to negative value
cgroup_path_ns_locked()
cgroup_path_ns()
bpf_iter_cgroup_show_fdinfo()
return value ignored
cgroup1_release_agent()
wasn't checking "too large" error
proc_cgroup_show()
already converted "too large" to negative value
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: <cgroups@vger.kernel.org>
Co-developed-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20231116192127.1558276-3-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231212211741.164376-3-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, the cpu_is_isolated() function checks only the statically
isolated CPUs specified via the "isolcpus" and "nohz_full" kernel
command line options. This function is used by vmstat and memcg to
reduce interference with isolated CPUs by not doing stat flushing
or scheduling works on those CPUs.
Workloads running on isolated CPUs within isolated cpuset
partitions should receive the same treatment to reduce unnecessary
interference. This patch introduces a new cpuset_cpu_is_isolated()
function to be called by cpu_is_isolated() so that the set of dynamically
created cpuset isolated CPUs will be included in the check.
Assuming that testing a bit in a cpumask is atomic, no synchronization
primitive is currently used to synchronize access to the cpuset's
isolated_cpus mask.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The root-only cpuset.cpus.isolated control file shows the current set
of isolated CPUs in isolated partitions. This control file is currently
exposed only with the cgroup_debug boot command line option which also
adds the ".__DEBUG__." prefix. This is actually a useful control file if
users want to find out which CPUs are currently in an isolated state by
the cpuset controller. Remove CFTYPE_DEBUG flag for this control file and
make it available by default without any prefix.
The test_cpuset_prs.sh test script and the cgroup-v2.rst documentation
file are also updated accordingly. Minor code change is also made in
test_cpuset_prs.sh to avoid false test failure when running on debug
kernel.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
To make CPUs in isolated cpuset partition closer in isolation to
the boot time isolated CPUs specified in the "isolcpus" boot command
line option, we need to take those CPUs out of the workqueue unbound
cpumask so that work functions from the unbound workqueues won't run
on those CPUs. Otherwise, they will interfere the user tasks running
on those isolated CPUs.
With the introduction of the workqueue_unbound_exclude_cpumask() helper
function in an earlier commit, those isolated CPUs can now be taken
out from the workqueue unbound cpumask.
This patch also updates cgroup-v2.rst to mention that isolated
CPUs will be excluded from unbound workqueue cpumask as well as
updating test_cpuset_prs.sh to verify the correctness of the new
*cpuset.cpus.isolated file, if available via cgroup_debug option.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add a new internal isolated_cpus mask to keep track of the CPUs that are in
isolated partitions. Expose that new cpumask as a new root-only control file
".cpuset.cpus.isolated".
tj: Updated patch description to reflect dropping __DEBUG__ prefix.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Smatch complains about returning negative error codes from a type
bool function.
kernel/cgroup/cpuset.c:705 cpu_exclusive_check() warn:
signedness bug returning '(-22)'
The code works correctly, but it is confusing. The current behavior is
that cpu_exclusive_check() returns true if it's *NOT* exclusive. Rename
it to cpusets_are_exclusive() and reverse the returns so it returns true
if it is exclusive and false if it's not. Update both callers as well.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/r/202309201706.2LhKdM6o-lkp@intel.com/
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When a local partition becomes invalid, it won't transition back to
valid partition automatically if a proper "cpuset.cpus.exclusive" or
"cpuset.cpus" change is made. Instead, system administrators have to
explicitly echo "root" or "isolated" into the "cpuset.cpus.partition"
file at the partition root.
This patch now enables the automatic transition of an invalid local
partition back to valid when there is a proper "cpuset.cpus.exclusive"
or "cpuset.cpus" change.
Automatic transition of an invalid remote partition to a valid one,
however, is not covered by this patch. They still need an explicit
write to "cpuset.cpus.partition" to become valid again.
The test_cpuset_prs.sh test script is updated to add new test cases to
test this automatic state transition.
Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/lkml/9777f0d2-2fdf-41cb-bd01-19c52939ef42@arm.com
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A user can pre-configure certain CPUs in an isolated state at boot time
with the "isolcpus" kernel boot command line option. Those CPUs will
not be in the housekeeping_cpumask(HK_TYPE_DOMAIN) and so will not
be in any sched domains. This may conflict with the partition setup
at runtime. Those boot time isolated CPUs should only be used in an
isolated partition.
This patch adds the necessary check and disallows partition setup if the
check fails.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
One can use "cpuset.cpus.partition" to create multiple scheduling domains
or to produce a set of isolated CPUs where load balancing is disabled.
The former use case is less common but the latter one can be frequently
used especially for the Telco use cases like DPDK.
The existing "isolated" partition can be used to produce isolated
CPUs if the applications have full control of a system. However, in a
containerized environment where all the apps are run in a container,
it is hard to distribute out isolated CPUs from the root down given
the unified hierarchy nature of cgroup v2.
The container running on isolated CPUs can be several layers down from
the root. The current partition feature requires that all the ancestors
of a leaf partition root must be parititon roots themselves. This can
be hard to configure.
This patch introduces a new type of partition called remote partition.
A remote partition is a partition whose parent is not a partition root
itself and its CPUs are acquired directly from available CPUs in the
top cpuset through a hierachical distribution of exclusive CPUs down
from it.
By contrast, the existing type of partitions where their parents have
to be valid partition roots are referred to as local partitions as they
have to be clustered around a parent partition root.
Child local partitons can be created under a remote partition, but
a remote partition cannot be created under a local partition. We may
relax this limitation in the future if there are use cases for such
configuration.
Manually writing to the "cpuset.cpus.exclusive" file is not necessary
when creating local partitions. However, writing proper values to
"cpuset.cpus.exclusive" down the cgroup hierarchy before the target
remote partition root is mandatory for the creation of a remote
partition.
The value in "cpuset.cpus.exclusive.effective" may change if its
"cpuset.cpus" or its parent's "cpuset.cpus.exclusive.effective" changes.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch introduces a new writable "cpuset.cpus.exclusive" control
file for v2 which will be added to non-root cpuset enabled cgroups. This new
file enables user to set a smaller list of exclusive CPUs to be used in
the creation of a cpuset partition.
The value written to "cpuset.cpus.exclusive" may not be the effective
value being used for the creation of cpuset partition, the effective
value will show up in "cpuset.cpus.exclusive.effective" and it is
subject to the constraint that it must also be a subset of cpus_allowed
and parent's "cpuset.cpus.exclusive.effective".
By writing to "cpuset.cpus.exclusive", "cpuset.cpus.exclusive.effective"
may be set to a non-empty value even for cgroups that are not valid
partition roots yet.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The creation of a cpuset partition means dedicating a set of exclusive
CPUs to be used by a particular partition only. These exclusive CPUs
will not be used by any cpusets outside of that partition.
To enable more flexibility in creating partitions, we need a way to
distribute exclusive CPUs that can be used in new partitions. Currently,
we have a subparts_cpus cpumask in struct cpuset that tracks only
the exclusive CPUs used by all the sub-partitions underneath a given
cpuset.
This patch reworks the way we do exclusive CPUs tracking. The
subparts_cpus is now renamed to effective_xcpus which tracks the
exclusive CPUs allocated to a partition root including those that are
further distributed down to sub-partitions underneath it. IOW, it also
includes the exclusive CPUs used by the current partition root. Note
that effective_xcpus can contain offline CPUs and it will always be a
subset of cpus_allowed.
The renamed effective_xcpus is now exposed via a new read-only
"cpuset.cpus.exclusive.effective" control file. The new effective_xcpus
cpumask should be set to cpus_allowed when a cpuset becomes a partition
root and be cleared if it is not a valid partition root.
In the next patch, we will enable write to another new control file to
enable further control of what can get into effective_xcpus.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit a86ce68078 ("cgroup/cpuset: Extract out CS_CPU_EXCLUSIVE
& CS_SCHED_LOAD_BALANCE handling") adds a new helper function
update_partition_sd_lb() to update the load balance state of the
cpuset. However the new load balance is determined by just looking at
whether the cpuset is a valid isolated partition root or not. That is
not enough if the cpuset is not a valid partition root but its parent
is in the isolated state (load balance off). Update the function to
set the new state to be the same as its parent in this case like what
has been done in commit c8c926200c ("cgroup/cpuset: Inherit parent's
load balance state in v2").
Fixes: a86ce68078 ("cgroup/cpuset: Extract out CS_CPU_EXCLUSIVE & CS_SCHED_LOAD_BALANCE handling")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add kernel-doc of param @rotor to fix warnings:
kernel/cgroup/cpuset.c:4162: warning: Function parameter or member
'rotor' not described in 'cpuset_spread_node'
kernel/cgroup/cpuset.c:3771: warning: Function parameter or member
'work' not described in 'cpuset_hotplug_workfn'
Signed-off-by: Cai Xinchen <caixinchen1@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A single partition setup and tear-down operation can lead to
multiple rebuild_sched_domains_locked() calls which is a waste of
effort. This can partly be mitigated by adding a flag to suppress the
rebuild_sched_domains_locked() call in update_cpumasks_hier(). Since
a Boolean flag has already been passed as the 3rd argument to
update_cpumasks_hier(), we can extend that to a full flag word.
The sched domain rebuild suppression is now enabled in
update_sibling_cpumasks() as all it callers will do the sched domain
rebuild after its return later on anyway.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The limitation that update_parent_subparts_cpumask() can only use
addmask & delmask in the given tmp cpumasks is fragile and may lead to
unexpected error.
Fix this problem by allocating/freeing a struct tmpmasks in
update_cpumask() to avoid reusing the cpumasks in trial_cs.
With this change, we can move the update_tasks_cpumask() for the
parent and update_sibling_cpumasks() for the sibling to inside
update_parent_subparts_cpumask().
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Extract out the setting of CS_CPU_EXCLUSIVE and CS_SCHED_LOAD_BALANCE
flags as well as the rebuilding of scheduling domains into the new
update_partition_exclusive() and update_partition_sd_lb() helper
functions to simplify the logic. The update_partition_exclusive()
helper is called mainly at the beginning of the caller, but it may be
called at the end too. The update_partition_sd_lb() helper is called
at the end of the caller.
This patch should reduce the chance that cpuset partition will end up
in an incorrect state.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit f28e22441f ("cgroup/cpuset: Add a new isolated
cpus.partition type"), the CS_SCHED_LOAD_BALANCE bit of a v2 cpuset
can be on or off. The child cpusets of a partition root must have the
same setting as its parent or it may screw up the rebuilding of sched
domains. Fix this problem by making sure the a child v2 cpuset will
follows its parent cpuset load balance state unless the child cpuset
is a new partition root itself.
Fixes: f28e22441f ("cgroup/cpuset: Add a new isolated cpus.partition type")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When we migrate a task between two cgroups, one of the checks is a
verification whether we can modify task's scheduler settings
(cap_task_setscheduler()).
An implicit migration occurs also when enabling a controller on the
unified hierarchy (think of parent to child migration). The
aforementioned check may be problematic if the caller of the migration
(enabling a controller) has no permissions over migrated tasks.
For instance, a user's cgroup that ends up running a process of a
different user. Although cgroup permissions are configured favorably,
the enablement fails due to the foreign process [1].
Change the behavior by relaxing the permissions check on the unified
hierarchy when no effective change would happen.
This is in accordance with unified hierarchy attachment behavior when
permissions of the source to target cgroups are decisive whereas the
migrated task is opaque (as opposed to more restrictive check in
__cgroup1_procs_write()).
Notice that foreign task's affinity may still be modified if the user
can modify destination cgroup's cpuset attributes
(update_tasks_cpumask() does no permissions check). The permissions
check could thus be skipped on v2 even when affinity changes. Stay
conservative in this patch though.
[1] https://github.com/systemd/systemd/issues/18293#issuecomment-831205649
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset_mutex unlock and lock pair is only needed when transferring tasks
out of empty cpuset. Avoid unneeded cpuset_mutex re-lock when !is_empty
to save cpu cycles.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
kthread_is_per_cpu() can be called directly without checking whether
PF_KTHREAD is set in task->flags. So remove PF_KTHREAD check to make
code more concise.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks
have been checked. DL BW is not allocated per-task but as a sum over
all DL tasks migrating.
If multiple controllers are attached to the cgroup next to the cpuset
controller a non-cpuset can_attach() can fail. In this case free DL BW
in cpuset_cancel_attach().
Finally, update cpuset DL task count (nr_deadline_tasks) only in
cpuset_attach().
Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
update_tasks_root_domain currently iterates over all tasks even if no
DEADLINE task is present on the cpuset/root domain for which bandwidth
accounting is being rebuilt. This has been reported to introduce 10+ ms
delays on suspend-resume operations.
Skip the costly iteration for cpusets that don't contain DEADLINE tasks.
Reported-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Qais reported that iterating over all tasks when rebuilding root domains
for finding out which ones are DEADLINE and need their bandwidth
correctly restored on such root domains can be a costly operation (10+
ms delays on suspend-resume).
To fix the problem keep track of the number of DEADLINE tasks belonging
to each cpuset and then use this information (followup patch) to only
perform the above iteration if DEADLINE tasks are actually present in
the cpuset for which a corresponding root domain is being rebuilt.
Reported-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Turns out percpu_cpuset_rwsem - commit 1243dc518c ("cgroup/cpuset:
Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea,
as it has been reported to cause slowdowns in workloads that need to
change cpuset configuration frequently and it is also not implementing
priority inheritance (which causes troubles with realtime workloads).
Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it
only for SCHED_DEADLINE tasks (other policies don't care about stable
cpusets anyway).
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
rebuild_root_domains() and update_tasks_root_domain() have neutral
names, but actually deal with DEADLINE bandwidth accounting.
Rename them to use 'dl_' prefix so that intent is more clear.
No functional change.
Suggested-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
* cpuset changes including the fix for an incorrect interaction with CPU
hotplug and an optimization.
* Other doc and cosmetic changes.
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Merge tag 'cgroup-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- cpuset changes including the fix for an incorrect interaction with
CPU hotplug and an optimization
- Other doc and cosmetic changes
* tag 'cgroup-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup-v1/cpusets: update libcgroup project link
cgroup/cpuset: Minor updates to test_cpuset_prs.sh
cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated
cgroup/cpuset: Skip task update if hotplug doesn't affect current cpuset
cpuset: Clean up cpuset_node_allowed
cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers
It is found that attaching a task to the top_cpuset does not currently
ignore CPUs allocated to subpartitions in cpuset_attach_task(). So the
code is changed to fix that.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In the case of CLONE_INTO_CGROUP, not all cpusets are ready to accept
new tasks. It is too late to check that in cpuset_fork(). So we need
to add the cpuset_can_fork() and cpuset_cancel_fork() methods to
pre-check it before we can allow attachment to a different cpuset.
We also need to set the attach_in_progress flag to alert other code
that a new task is going to be added to the cpuset.
Fixes: ef2c41cf38 ("clone3: allow spawning processes into cgroups")
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Tejun Heo <tj@kernel.org>
By default, the clone(2) syscall spawn a child process into the same
cgroup as its parent. With the use of the CLONE_INTO_CGROUP flag
introduced by commit ef2c41cf38 ("clone3: allow spawning processes
into cgroups"), the child will be spawned into a different cgroup which
is somewhat similar to writing the child's tid into "cgroup.threads".
The current cpuset_fork() method does not properly handle the
CLONE_INTO_CGROUP case where the cpuset of the child may be different
from that of its parent. Update the cpuset_fork() method to treat the
CLONE_INTO_CGROUP case similar to cpuset_attach().
Since the newly cloned task has not been running yet, its actual
memory usage isn't known. So it is not necessary to make change to mm
in cpuset_fork().
Fixes: ef2c41cf38 ("clone3: allow spawning processes into cgroups")
Reported-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Tejun Heo <tj@kernel.org>
After a successful cpuset_can_attach() call which increments the
attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach()
will be called later. In cpuset_attach(), tasks in cpuset_attach_wq,
if present, will be woken up at the end. That is not the case in
cpuset_cancel_attach(). So missed wakeup is possible if the attach
operation is somehow cancelled. Fix that by doing the wakeup in
cpuset_cancel_attach() as well.
Fixes: e44193d39e ("cpuset: let hotplug propagation work wait for task attaching")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: stable@vger.kernel.org # v3.11+
Signed-off-by: Tejun Heo <tj@kernel.org>
Similar to commit 3fb906e7fa ("group/cpuset: Don't filter offline
CPUs in cpuset_cpus_allowed() for top cpuset tasks"), the whole set of
possible CPUs including offline ones should be used for setting cpumasks
for tasks in the top cpuset when a cpuset partition is modified as the
hotplug code won't update cpumasks for tasks in the top cpuset when
CPUs become online or offline.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
If a hotplug event doesn't affect the current cpuset, there is no point
to call hotplug_update_tasks() or hotplug_update_tasks_legacy(). So
just skip it.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was found that commit 7a2127e66a ("cpuset: Call
set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug
that corrupted "cpuset.cpus" of a partition root when it was updated.
It is because the tmp->new_cpus field of the passed tmp parameter
of update_parent_subparts_cpumask() should not be used at all as
it contains important cpumask data that should not be overwritten.
Fix it by using tmp->addmask instead.
Also update update_cpumask() to make sure that trialcs->cpu_allowed
will not be corrupted until it is no longer needed.
Fixes: 7a2127e66a ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task")
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v6.2+
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 002f290627 ("cpuset: use static key better and convert to new API")
has used __cpuset_node_allowed() instead of cpuset_node_allowed() to check
whether we can allocate on a memory node. Now this function isn't used by
anyone, so we can do the follow things to clean up it.
1. remove unused codes
2. rename __cpuset_node_allowed() to cpuset_node_allowed()
3. update comments in mm/page_alloc.c
Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
All the commits are trivial. Doc updates and a trivial code cleanup.
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Merge tag 'cgroup-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"All the changes are trivial: documentation updates and a trivial code
cleanup"
* tag 'cgroup-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: fix a few kernel-doc warnings & coding style
docs: cgroup-v1: use numbered lists for user interface setup
docs: cgroup-v1: add internal cross-references
docs: cgroup-v1: make swap extension subsections subsections
docs: cgroup-v1: use bullet lists for list of stat file tables
docs: cgroup-v1: move hierarchy of accounting caption
docs: cgroup-v1: fix footnotes
docs: cgroup-v1: use code block for locking order schema
docs: cgroup-v1: wrap remaining admonitions in admonition blocks
docs: cgroup-v1: replace custom note constructs with appropriate admonition blocks
cgroup/cpuset: no need to explicitly init a global static variable
set_cpus_allowed_ptr() will fail with -EINVAL if the requested
affinity mask is not a subset of the task_cpu_possible_mask() for the
task being updated. Consequently, on a heterogeneous system with cpusets
spanning the different CPU types, updates to the cgroup hierarchy can
silently fail to update task affinities when the effective affinity
mask for the cpuset is expanded.
For example, consider an arm64 system with 4 CPUs, where CPUs 2-3 are
the only cores capable of executing 32-bit tasks. Attaching a 32-bit
task to a cpuset containing CPUs 0-2 will correctly affine the task to
CPU 2. Extending the cpuset to CPUs 0-3, however, will fail to extend
the affinity mask of the 32-bit task because update_tasks_cpumask() will
pass the full 0-3 mask to set_cpus_allowed_ptr().
Extend update_tasks_cpumask() to take a temporary 'cpumask' paramater
and use it to mask the 'effective_cpus' mask with the possible mask for
each task being updated.
Fixes: 431c69fac0 ("cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()")
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 8f9ea86fdf ("sched: Always preserve the user
requested cpumask"), relax_compatible_cpus_allowed_ptr() is calling
__sched_setaffinity() unconditionally. This helps to expose a bug in
the current cpuset hotplug code where the cpumasks of the tasks in
the top cpuset are not updated at all when some CPUs become online or
offline. It is likely caused by the fact that some of the tasks in the
top cpuset, like percpu kthreads, cannot have their cpu affinity changed.
One way to reproduce this as suggested by Peter is:
- boot machine
- offline all CPUs except one
- taskset -p ffffffff $$
- online all CPUs
Fix this by allowing cpuset_cpus_allowed() to return a wider mask that
includes offline CPUs for those tasks that are in the top cpuset. For
tasks not in the top cpuset, the old rule applies and only online CPUs
will be returned in the mask since hotplug events will update their
cpumasks accordingly.
Fixes: 8f9ea86fdf ("sched: Always preserve the user requested cpumask")
Reported-by: Will Deacon <will@kernel.org>
Originally-from: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Will Deacon <will@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was found that the check to see if a partition could use up all
the cpus from the parent cpuset in update_parent_subparts_cpumask()
was incorrect. As a result, it is possible to leave parent with no
effective cpu left even if there are tasks in the parent cpuset. This
can lead to system panic as reported in [1].
Fix this probem by updating the check to fail the enabling the partition
if parent's effective_cpus is a subset of the child's cpus_allowed.
Also record the error code when an error happens in update_prstate()
and add a test case where parent partition and child have the same cpu
list and parent has task. Enabling partition in the child will fail in
this case.
[1] https://www.spinics.net/lists/cgroups/msg36254.html
Fixes: f0af1bfc27 ("cgroup/cpuset: Relax constraints to partition & cpus changes")
Cc: stable@vger.kernel.org # v6.1
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix kernel-doc notation warnings:
kernel/cgroup/cpuset.c:1309: warning: Excess function parameter 'cpuset' description in 'update_parent_subparts_cpumask'
kernel/cgroup/cpuset.c:3909: warning: expecting prototype for cpuset_mem_spread_node(). Prototype was for cpuset_spread_node() instead
Also drop a blank line before EXPORT_SYMBOL_GPL() to be consistent
with kernel coding style.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: cgroups@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset_rwsem is a static variable defined with DEFINE_STATIC_PERCPU_RWSEM().
It's initialized at build time and so there's no need for explicit runtime
init leaking one percpu int.
Signed-off-by: Daniel Vacek <neelx@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
- More userfaultfs work from Peter Xu.
- Several convert-to-folios series from Sidhartha Kumar and Huang Ying.
- Some filemap cleanups from Vishal Moola.
- David Hildenbrand added the ability to selftest anon memory COW handling.
- Some cpuset simplifications from Liu Shixin.
- Addition of vmalloc tracing support by Uladzislau Rezki.
- Some pagecache folioifications and simplifications from Matthew Wilcox.
- A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use it.
- Miguel Ojeda contributed some cleanups for our use of the
__no_sanitize_thread__ gcc keyword. This series shold have been in the
non-MM tree, my bad.
- Naoya Horiguchi improved the interaction between memory poisoning and
memory section removal for huge pages.
- DAMON cleanups and tuneups from SeongJae Park
- Tony Luck fixed the handling of COW faults against poisoned pages.
- Peter Xu utilized the PTE marker code for handling swapin errors.
- Hugh Dickins reworked compound page mapcount handling, simplifying it
and making it more efficient.
- Removal of the autonuma savedwrite infrastructure from Nadav Amit and
David Hildenbrand.
- zram support for multiple compression streams from Sergey Senozhatsky.
- David Hildenbrand reworked the GUP code's R/O long-term pinning so
that drivers no longer need to use the FOLL_FORCE workaround which
didn't work very well anyway.
- Mel Gorman altered the page allocator so that local IRQs can remnain
enabled during per-cpu page allocations.
- Vishal Moola removed the try_to_release_page() wrapper.
- Stefan Roesch added some per-BDI sysfs tunables which are used to
prevent network block devices from dirtying excessive amounts of
pagecache.
- David Hildenbrand did some cleanup and repair work on KSM COW
breaking.
- Nhat Pham and Johannes Weiner have implemented writeback in zswap's
zsmalloc backend.
- Brian Foster has fixed a longstanding corner-case oddity in
file[map]_write_and_wait_range().
- sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
Chen.
- Shiyang Ruan has done some work on fsdax, to make its reflink mode
work better under xfstests. Better, but still not perfect.
- Christoph Hellwig has removed the .writepage() method from several
filesystems. They only need .writepages().
- Yosry Ahmed wrote a series which fixes the memcg reclaim target
beancounting.
- David Hildenbrand has fixed some of our MM selftests for 32-bit
machines.
- Many singleton patches, as usual.
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Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- More userfaultfs work from Peter Xu
- Several convert-to-folios series from Sidhartha Kumar and Huang Ying
- Some filemap cleanups from Vishal Moola
- David Hildenbrand added the ability to selftest anon memory COW
handling
- Some cpuset simplifications from Liu Shixin
- Addition of vmalloc tracing support by Uladzislau Rezki
- Some pagecache folioifications and simplifications from Matthew
Wilcox
- A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
it
- Miguel Ojeda contributed some cleanups for our use of the
__no_sanitize_thread__ gcc keyword.
This series should have been in the non-MM tree, my bad
- Naoya Horiguchi improved the interaction between memory poisoning and
memory section removal for huge pages
- DAMON cleanups and tuneups from SeongJae Park
- Tony Luck fixed the handling of COW faults against poisoned pages
- Peter Xu utilized the PTE marker code for handling swapin errors
- Hugh Dickins reworked compound page mapcount handling, simplifying it
and making it more efficient
- Removal of the autonuma savedwrite infrastructure from Nadav Amit and
David Hildenbrand
- zram support for multiple compression streams from Sergey Senozhatsky
- David Hildenbrand reworked the GUP code's R/O long-term pinning so
that drivers no longer need to use the FOLL_FORCE workaround which
didn't work very well anyway
- Mel Gorman altered the page allocator so that local IRQs can remnain
enabled during per-cpu page allocations
- Vishal Moola removed the try_to_release_page() wrapper
- Stefan Roesch added some per-BDI sysfs tunables which are used to
prevent network block devices from dirtying excessive amounts of
pagecache
- David Hildenbrand did some cleanup and repair work on KSM COW
breaking
- Nhat Pham and Johannes Weiner have implemented writeback in zswap's
zsmalloc backend
- Brian Foster has fixed a longstanding corner-case oddity in
file[map]_write_and_wait_range()
- sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
Chen
- Shiyang Ruan has done some work on fsdax, to make its reflink mode
work better under xfstests. Better, but still not perfect
- Christoph Hellwig has removed the .writepage() method from several
filesystems. They only need .writepages()
- Yosry Ahmed wrote a series which fixes the memcg reclaim target
beancounting
- David Hildenbrand has fixed some of our MM selftests for 32-bit
machines
- Many singleton patches, as usual
* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
mm: mmu_gather: allow more than one batch of delayed rmaps
mm: fix typo in struct pglist_data code comment
kmsan: fix memcpy tests
mm: add cond_resched() in swapin_walk_pmd_entry()
mm: do not show fs mm pc for VM_LOCKONFAULT pages
selftests/vm: ksm_functional_tests: fixes for 32bit
selftests/vm: cow: fix compile warning on 32bit
selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
mm,thp,rmap: fix races between updates of subpages_mapcount
mm: memcg: fix swapcached stat accounting
mm: add nodes= arg to memory.reclaim
mm: disable top-tier fallback to reclaim on proactive reclaim
selftests: cgroup: make sure reclaim target memcg is unprotected
selftests: cgroup: refactor proactive reclaim code to reclaim_until()
mm: memcg: fix stale protection of reclaim target memcg
mm/mmap: properly unaccount memory on mas_preallocate() failure
omfs: remove ->writepage
jfs: remove ->writepage
...
Change the function argument in the description of cpuset_css_alloc()
from 'struct cgroup' -> 'struct cgroup_subsys_state'. The change to the
argument type was introduced by commit eb95419b02 ("cgroup: pass
around cgroup_subsys_state instead of cgroup in subsystem methods").
Also, add more information to its description.
Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Joel Savitz <jsavitz@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was found that with the default hierarchy, enabling cpuset in the
child cgroups can trigger a cpuset_attach() call in each of the child
cgroups that have tasks with no change in effective cpus and mems. If
there are many processes in those child cgroups, it will burn quite a
lot of cpu cycles iterating all the tasks without doing useful work.
Optimizing this case by comparing between the old and new cpusets and
skip useless update if there is no change in effective cpus and mems.
Also mems_allowed are less likely to be changed than cpus_allowed. So
skip changing mm if there is no change in effective_mems and
CS_MEMORY_MIGRATE is not set.
By inserting some instrumentation code and running a simple command in
a container 200 times in a cgroup v2 system, it was found that all the
cpuset_attach() calls are skipped (401 times in total) as there was no
change in effective cpus and mems.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cpuset v2 has no spread flags to set. So we can skip spread
flags update if cpuset v2 is being used. Also change the name to
cpuset_update_task_spread_flags() to indicate that there are multiple
spread flags.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The priority of hotplug memory callback is defined in a different file.
And there are some callers using numbers directly. Collect them together
into include/linux/memory.h for easy reading. This allows us to sort
their priorities more intuitively without additional comments.
Link: https://lkml.kernel.org/r/20220923033347.3935160-9-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: Use hotplug_memory_notifier() instead of
register_hotmemory_notifier()", v4.
Commit f02c696800 ("include/linux/memory.h: implement
register_hotmemory_notifier()") introduced register_hotmemory_notifier()
to avoid a compile problem with gcc-4.4.4:
When CONFIG_MEMORY_HOTPLUG=n, we don't want the memory-hotplug notifier
handlers to be included in the .o files, for space reasons.
The existing hotplug_memory_notifier() tries to handle this but testing
with gcc-4.4.4 shows that it doesn't work - the hotplug functions are
still present in the .o files.
Since commit 76ae847497 ("Documentation: raise minimum supported
version of GCC to 5.1") has already updated the minimum gcc version to
5.1. The previous problem mentioned in f02c696800 does not exist. So
we can now revert to use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().
In the last patch, we move all hotplug memory notifier priority to same
file for easy sorting.
This patch (of 8):
Commit 76ae847497 ("Documentation: raise minimum supported version of
GCC to 5.1") updated the minimum gcc version to 5.1. So the problem
mentioned in f02c696800 ("include/linux/memory.h: implement
register_hotmemory_notifier()") no longer exist. So we can now switch to
use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().
Link: https://lkml.kernel.org/r/20220923033347.3935160-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20220923033347.3935160-2-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, changes in "cpust.cpus" of a partition root is not allowed if
it violates the sibling cpu exclusivity rule when the check is done
in the validate_change() function. That is inconsistent with the
other cpuset changes that are always allowed but may make a partition
invalid.
Update the cpuset code to allow cpumask change even if it violates the
sibling cpu exclusivity rule, but invalidate the partition instead
just like the other changes. However, other sibling partitions with
conflicting cpumask will also be invalidated in order to not violating
the exclusivity rule. This behavior is specific to this partition
rule violation.
Note that a previous commit has made sibling cpu exclusivity rule check
the last check of validate_change(). So if -EINVAL is returned, we can
be sure that sibling cpu exclusivity rule violation is the only rule
that is broken.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch moves down the exclusive cpu and memory check in
validate_change(). There is no functional change.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There are a number of different reasons which can cause a partition to
become invalid. A user seeing an invalid partition may not know exactly
why. To help user to get a better understanding of the underlying reason,
The cpuset.cpus.partition control file, when read, will now report the
reason why a partition become invalid. When a partition does become
invalid, reading the control file will show "root invalid (<reason>)"
where <reason> is a string that describes why the partition is invalid.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cpuset v1 uses the sched_load_balance control file to determine if load
balancing should be enabled. Cpuset v2 gets rid of sched_load_balance
as its use may require disabling load balancing at cgroup root.
For workloads that require very low latency like DPDK, the latency
jitters caused by periodic load balancing may exceed the desired
latency limit.
When cpuset v2 is in use, the only way to avoid this latency cost is to
use the "isolcpus=" kernel boot option to isolate a set of CPUs. After
the kernel boot, however, there is no way to add or remove CPUs from
this isolated set. For workloads that are more dynamic in nature, that
means users have to provision enough CPUs for the worst case situation
resulting in excess idle CPUs.
To address this issue for cpuset v2, a new cpuset.cpus.partition type
"isolated" is added which allows the creation of a cpuset partition
without load balancing. This will allow system administrators to
dynamically adjust the size of isolated partition to the current need
of the workload without rebooting the system.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, enabling a partition root is only allowed if all the
constraints of a valid partition are satisfied. Even changes to
"cpuset.cpus" may not be allowed in some cases. Moreover, there are
limits to changes made to a parent cpuset if it is a valid partition
root. This is contrary to the general cgroup v2 philosophy.
This patch relaxes the constraints of changing the state of "cpuset.cpus"
and "cpuset.cpus.partition". Now all valid changes ("member" or "root")
to "cpuset.cpus.partition" are allowed even if there are child cpusets
underneath it.
Trying to make a cpuset a partition root, however, will cause its state
to become invalid if the following constraints of a valid partition
root are not satisfied.
1) The "cpuset.cpus" is non-empty and exclusive.
2) The parent cpuset is a valid partition root.
3) The "cpuset.cpus" overlaps parent's "cpuset.cpus".
Similarly, almost all changes to "cpuset.cpus" are allowed with the
exception that if the underlying CS_CPU_EXCLUSIVE flag is set, the
exclusivity rule will still apply.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, a partition root cannot have empty "cpuset.cpus.effective".
As a result, a parent partition root cannot distribute out all its
CPUs to child partitions with no CPUs left. However in most cases,
there shouldn't be any tasks associated with intermediate nodes of the
default hierarchy. So the current rule is too restrictive and can waste
valuable CPU resource.
To address this issue, we are now allowing a partition to have empty
"cpuset.cpus.effective" as long as it has no task. Since cpuset is
threaded, no-internal-process rule does not apply. So it is possible
to have tasks in a partition root with child sub-partitions even though
that should be uncommon.
A parent partition with no task can now have all its CPUs distributed out
to its child partitions. The top cpuset always have some house-keeping
tasks running and so its list of effective cpu can't be empty.
Once a partition with empty "cpuset.cpus.effective" is formed, no
new task can be moved into it until "cpuset.cpus.effective" becomes
non-empty.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The partition root state (PRS) macro names do not currently match the
external names. Change them to match the external names and add helper
functions to read or change the state.
Shorten the cpuset argument of update_parent_subparts_cpumask() to cs
to match other cpuset functions.
Remove the new_prs argument from notify_partition_change() as the
cs->partition_root_state has already been set to new_prs before it
is called.
There is no functional change.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Previously, update_tasks_cpumask() is not supposed to be called with
top cpuset. With cpuset partition that takes CPUs away from the top
cpuset, adjusting the cpus_mask of the tasks in the top cpuset is
necessary. Percpu kthreads, however, are ignored.
Fixes: ee8dde0cd2 ("cpuset: Add new v2 cpuset.sched.partition flag")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Bringing up a CPU may involve creating and destroying tasks which requires
read-locking threadgroup_rwsem, so threadgroup_rwsem nests inside
cpus_read_lock(). However, cpuset's ->attach(), which may be called with
thredagroup_rwsem write-locked, also wants to disable CPU hotplug and
acquires cpus_read_lock(), leading to a deadlock.
Fix it by guaranteeing that ->attach() is always called with CPU hotplug
disabled and removing cpus_read_lock() call from cpuset_attach().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-and-tested-by: Imran Khan <imran.f.khan@oracle.com>
Reported-and-tested-by: Xuewen Yan <xuewen.yan@unisoc.com>
Fixes: 05c7b7a92c ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug")
Cc: stable@vger.kernel.org # v5.17+
With cgroup v2, the cpuset's cpus_allowed mask can be empty indicating
that the cpuset will just use the effective CPUs of its parent. So
cpuset_can_attach() can call task_can_attach() with an empty mask.
This can lead to cpumask_any_and() returns nr_cpu_ids causing the call
to dl_bw_of() to crash due to percpu value access of an out of bound
CPU value. For example:
[80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0
:
[80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0
:
[80468.207946] Call Trace:
[80468.208947] cpuset_can_attach+0xa0/0x140
[80468.209953] cgroup_migrate_execute+0x8c/0x490
[80468.210931] cgroup_update_dfl_csses+0x254/0x270
[80468.211898] cgroup_subtree_control_write+0x322/0x400
[80468.212854] kernfs_fop_write_iter+0x11c/0x1b0
[80468.213777] new_sync_write+0x11f/0x1b0
[80468.214689] vfs_write+0x1eb/0x280
[80468.215592] ksys_write+0x5f/0xe0
[80468.216463] do_syscall_64+0x5c/0x80
[80468.224287] entry_SYSCALL_64_after_hwframe+0x44/0xae
Fix that by using effective_cpus instead. For cgroup v1, effective_cpus
is the same as cpus_allowed. For v2, effective_cpus is the real cpumask
to be used by tasks within the cpuset anyway.
Also update task_can_attach()'s 2nd argument name to cs_effective_cpus to
reflect the change. In addition, a check is added to task_can_attach()
to guard against the possibility that cpumask_any_and() may return a
value >= nr_cpu_ids.
Fixes: 7f51412a41 ("sched/deadline: Fix bandwidth check/update when migrating tasks between exclusive cpusets")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220803015451.2219567-1-longman@redhat.com
There are 3 places where the cpu and node masks of the top cpuset can
be initialized in the order they are executed:
1) start_kernel -> cpuset_init()
2) start_kernel -> cgroup_init() -> cpuset_bind()
3) kernel_init_freeable() -> do_basic_setup() -> cpuset_init_smp()
The first cpuset_init() call just sets all the bits in the masks.
The second cpuset_bind() call sets cpus_allowed and mems_allowed to the
default v2 values. The third cpuset_init_smp() call sets them back to
v1 values.
For systems with cgroup v2 setup, cpuset_bind() is called once. As a
result, cpu and memory node hot add may fail to update the cpu and node
masks of the top cpuset to include the newly added cpu or node in a
cgroup v2 environment.
For systems with cgroup v1 setup, cpuset_bind() is called again by
rebind_subsystem() when the v1 cpuset filesystem is mounted as shown
in the dmesg log below with an instrumented kernel.
[ 2.609781] cpuset_bind() called - v2 = 1
[ 3.079473] cpuset_init_smp() called
[ 7.103710] cpuset_bind() called - v2 = 0
smp_init() is called after the first two init functions. So we don't
have a complete list of active cpus and memory nodes until later in
cpuset_init_smp() which is the right time to set up effective_cpus
and effective_mems.
To fix this cgroup v2 mask setup problem, the potentially incorrect
cpus_allowed & mems_allowed setting in cpuset_init_smp() are removed.
For cgroup v2 systems, the initial cpuset_bind() call will set the masks
correctly. For cgroup v1 systems, the second call to cpuset_bind()
will do the right setup.
cc: stable@vger.kernel.org
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull cgroup updates from Tejun Heo:
"All trivial cleanups without meaningful behavior changes"
* 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: cleanup comments
cgroup: Fix cgroup_can_fork() and cgroup_post_fork() kernel-doc comment
cgroup: rstat: retrieve current bstat to delta directly
cgroup: rstat: use same convention to assign cgroup_base_stat
for spdx, add a space before //
replacements
judgement to judgment
transofrmed to transformed
partitition to partition
histrical to historical
migratecd to migrated
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix the following W=1 kernel warnings:
kernel/cgroup/cpuset.c:3718: warning: expecting prototype for
cpuset_memory_pressure_bump(). Prototype was for
__cpuset_memory_pressure_bump() instead.
kernel/cgroup/cpuset.c:3568: warning: expecting prototype for
cpuset_node_allowed(). Prototype was for __cpuset_node_allowed()
instead.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Merge tag 'v5.17-rc5' into sched/core, to resolve conflicts
New conflicts in sched/core due to the following upstream fixes:
44585f7bc0 ("psi: fix "defined but not used" warnings when CONFIG_PROC_FS=n")
a06247c680 ("psi: Fix uaf issue when psi trigger is destroyed while being polled")
Conflicts:
include/linux/psi_types.h
kernel/sched/psi.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Refer to housekeeping APIs using single feature types instead of flags.
This prevents from passing multiple isolation features at once to
housekeeping interfaces, which soon won't be possible anymore as each
isolation features will have their own cpumask.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
As previously discussed(https://lkml.org/lkml/2022/1/20/51),
cpuset_attach() is affected with similar cpu hotplug race,
as follow scenario:
cpuset_attach() cpu hotplug
--------------------------- ----------------------
down_write(cpuset_rwsem)
guarantee_online_cpus() // (load cpus_attach)
sched_cpu_deactivate
set_cpu_active()
// will change cpu_active_mask
set_cpus_allowed_ptr(cpus_attach)
__set_cpus_allowed_ptr_locked()
// (if the intersection of cpus_attach and
cpu_active_mask is empty, will return -EINVAL)
up_write(cpuset_rwsem)
To avoid races such as described above, protect cpuset_attach() call
with cpu_hotplug_lock.
Fixes: be367d0992 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time")
Cc: stable@vger.kernel.org # v2.6.32+
Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was found that a "suspicious RCU usage" lockdep warning was issued
with the rcu_read_lock() call in update_sibling_cpumasks(). It is
because the update_cpumasks_hier() function may sleep. So we have
to release the RCU lock, call update_cpumasks_hier() and reacquire
it afterward.
Also add a percpu_rwsem_assert_held() in update_sibling_cpumasks()
instead of stating that in the comment.
Fixes: 4716909cc5 ("cpuset: Track cpusets that use parent's effective_cpus")
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
subparts_cpus should be limited as a subset of cpus_allowed, but it is
updated wrongly by using cpumask_andnot(). Use cpumask_and() instead to
fix it.
Fixes: ee8dde0cd2 ("cpuset: Add new v2 cpuset.sched.partition flag")
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit 1f1562fcd0 ("cgroup/cpuset: Don't let child cpusets
restrict parent in default hierarchy") inteded to relax the check only
on the default hierarchy (or v2 mode) but it dropped the check in v1
too.
This patch returns and separates the legacy-only validations so that
they can be considered only in the v1 mode, which should enforce the old
constraints for the sake of compatibility.
Fixes: 1f1562fcd0 ("cgroup/cpuset: Don't let child cpusets restrict parent in default hierarchy")
Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Convert 'allowed' in __cpuset_node_allowed() to be boolean since the
return types of node_isset() and __cpuset_node_allowed() are both
boolean.
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In validate_change(), there is a check since v2.6.12 to make sure that
each of the child cpusets must be a subset of a parent cpuset. IOW, it
allows child cpusets to restrict what changes can be made to a parent's
"cpuset.cpus". This actually violates one of the core principles of the
default hierarchy where a cgroup higher up in the hierarchy should be
able to change configuration however it sees fit as deligation breaks
down otherwise.
To address this issue, the check is now removed for the default hierarchy
to free parent cpusets from being restricted by child cpusets. The
check will still apply for legacy hierarchy.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There was a report that starting an Ubuntu in docker while using cpuset
to bind it to movable nodes (a node only has movable zone, like a node
for hotplug or a Persistent Memory node in normal usage) will fail due
to memory allocation failure, and then OOM is involved and many other
innocent processes got killed.
It can be reproduced with command:
$ docker run -it --rm --cpuset-mems 4 ubuntu:latest bash -c "grep Mems_allowed /proc/self/status"
(where node 4 is a movable node)
runc:[2:INIT] invoked oom-killer: gfp_mask=0x500cc2(GFP_HIGHUSER|__GFP_ACCOUNT), order=0, oom_score_adj=0
CPU: 8 PID: 8291 Comm: runc:[2:INIT] Tainted: G W I E 5.8.2-0.g71b519a-default #1 openSUSE Tumbleweed (unreleased)
Hardware name: Dell Inc. PowerEdge R640/0PHYDR, BIOS 2.6.4 04/09/2020
Call Trace:
dump_stack+0x6b/0x88
dump_header+0x4a/0x1e2
oom_kill_process.cold+0xb/0x10
out_of_memory.part.0+0xaf/0x230
out_of_memory+0x3d/0x80
__alloc_pages_slowpath.constprop.0+0x954/0xa20
__alloc_pages_nodemask+0x2d3/0x300
pipe_write+0x322/0x590
new_sync_write+0x196/0x1b0
vfs_write+0x1c3/0x1f0
ksys_write+0xa7/0xe0
do_syscall_64+0x52/0xd0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Mem-Info:
active_anon:392832 inactive_anon:182 isolated_anon:0
active_file:68130 inactive_file:151527 isolated_file:0
unevictable:2701 dirty:0 writeback:7
slab_reclaimable:51418 slab_unreclaimable:116300
mapped:45825 shmem:735 pagetables:2540 bounce:0
free:159849484 free_pcp:73 free_cma:0
Node 4 active_anon:1448kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB all_unreclaimable? no
Node 4 Movable free:130021408kB min:9140kB low:139160kB high:269180kB reserved_highatomic:0KB active_anon:1448kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:130023424kB managed:130023424kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:292kB local_pcp:84kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0 0
Node 4 Movable: 1*4kB (M) 0*8kB 0*16kB 1*32kB (M) 0*64kB 0*128kB 1*256kB (M) 1*512kB (M) 1*1024kB (M) 0*2048kB 31743*4096kB (M) = 130021156kB
oom-kill:constraint=CONSTRAINT_CPUSET,nodemask=(null),cpuset=docker-9976a269caec812c134fa317f27487ee36e1129beba7278a463dd53e5fb9997b.scope,mems_allowed=4,global_oom,task_memcg=/system.slice/containerd.service,task=containerd,pid=4100,uid=0
Out of memory: Killed process 4100 (containerd) total-vm:4077036kB, anon-rss:51184kB, file-rss:26016kB, shmem-rss:0kB, UID:0 pgtables:676kB oom_score_adj:0
oom_reaper: reaped process 8248 (docker), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 2054 (node_exporter), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 1452 (systemd-journal), now anon-rss:0kB, file-rss:8564kB, shmem-rss:4kB
oom_reaper: reaped process 2146 (munin-node), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 8291 (runc:[2:INIT]), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
The reason is that in this case, the target cpuset nodes only have
movable zone, while the creation of an OS in docker sometimes needs to
allocate memory in non-movable zones (dma/dma32/normal) like
GFP_HIGHUSER, and the cpuset limit forbids the allocation, then
out-of-memory killing is involved even when normal nodes and movable
nodes both have many free memory.
The OOM killer cannot help to resolve the situation as there is no
usable memory for the request in the cpuset scope. The only reasonable
measure to take is to fail the allocation right away and have the caller
to deal with it.
So add a check for cases like this in the slowpath of allocation, and
bail out early returning NULL for the allocation.
As page allocation is one of the hottest path in kernel, this check will
hurt all users with sane cpuset configuration, add a static branch check
and detect the abnormal config in cpuset memory binding setup so that
the extra check cost in page allocation is not paid by everyone.
[thanks to Micho Hocko and David Rientjes for suggesting not handling
it inside OOM code, adding cpuset check, refining comments]
Link: https://lkml.kernel.org/r/1632481657-68112-1-git-send-email-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 1243dc518c ("cgroup/cpuset: Convert cpuset_mutex to
percpu_rwsem"), cpuset_mutex has been replaced by cpuset_rwsem which is
a percpu rwsem. However, the comments in kernel/cgroup/cpuset.c still
reference cpuset_mutex which are now incorrect.
Change all the references of cpuset_mutex to cpuset_rwsem.
Fixes: 1243dc518c ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
