Monitors generated with dot2k have their registration function (the one
called during monitor initialisation) return always 0, even if the
registration failed on RV side.
This can hide potential errors.
Return the value returned by the RV register function.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Link: https://lore.kernel.org/20250723161240.194860-6-gmonaco@redhat.com
Reviewed-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The current behaviour of rvgen when running with the -a option is to
append the necessary lines at the end of the configuration for Kconfig,
Makefile and tracepoints.
This is not always the desired behaviour in case of nested monitors:
while tracepoints are not affected by nesting and the Makefile's only
requirement is that the parent monitor is built before its children, in
the Kconfig it is better to have children defined right after their
parent, otherwise the result has wrong indentation:
[*] foo_parent monitor
[*] foo_child1 monitor
[*] foo_child2 monitor
[*] bar_parent monitor
[*] bar_child1 monitor
[*] bar_child2 monitor
[*] foo_child3 monitor
[*] foo_child4 monitor
Adapt rvgen to look for a different marker for nested monitors in the
Kconfig file and append the line right after the last sibling, instead
of the last monitor.
Also add the marker when creating a new parent monitor.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Link: https://lore.kernel.org/20250723161240.194860-5-gmonaco@redhat.com
Reviewed-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The dot2c.py script generates all states in a single line. This breaks the
100 column limit when the state machines are non-trivial.
Change dot2c.py to generate the states in separate lines in case the
generated line is going to be too long.
Also adapt existing monitors with line length over the limit.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Link: https://lore.kernel.org/20250723161240.194860-4-gmonaco@redhat.com
Suggested-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
eprobes are dynamic events that can read other events using their fields
to create new events. Currently it doesn't work with arrays. When the new
event field is attached to the old event field, it looks at the size of
the field to determine what type of field the new field should be. For 1
byte fields it's a char, for 2 bytes, it's a short and for 4 bytes it's an
integer. For all other sizes it just defaults to "long". This also reads
the contents of the field for such cases.
For arrays that are bigger than the size of long, return the value of the
address of the content itself. This will allow eprobes to read other
values in the array of the old event.
This is useful when raw_syscalls is enabled but the syscall events are
not. The syscall events are created from the raw_syscalls as they have an
array of "args" that holds the 6 long words passed to the syscall entry
point. To read the value of "filename" from sys_openat, the eprobe could
attach to the raw_syscall and read the second value.
It can then even be passed to a synthetic event and converted back to
another eprobe to get the value of "filename" after it has been read by
the kernel during the system call:
[
Create an eprobe called "sys" and attach it to sys_enter.
Read the id of the system call and the second argument
]
# echo 'e:sys raw_syscalls.sys_enter nr=$id:u32 arg2=+8($args):u64' >> /sys/kernel/tracing/dynamic_events
[
Create a synthetic event "path" that will hold the address of the
sys_openat filename. This is on a 64bit machine, so make it 64 bits
]
# echo 's:path u64 file;' >> /sys/kernel/tracing/dynamic_events
[
Add a histogram to the eprobe/sys which tiggers if the "nr" field is
257 (sys_openat), and save the filename in the "file" variable.
]
# echo 'hist:keys=common_pid:file=arg2 if nr == 257' > /sys/kernel/tracing/events/eprobes/sys/trigger
[
Attach a histogram to sys_exit event that triggers the "path" synthetic
event and records the "filename" that was passed from the sys eprobe.
]
# echo 'hist:keys=common_pid:f=$file:onmatch(eprobes.sys).trace(path,$f)' >> /sys/kernel/tracing/events/raw_syscalls/sys_exit/trigger
[
Create another eprobe that dereferences the "file" field as a user
space string and displays it.
]
# echo 'e:open synthetic.path file=+0($file):ustring' >> /sys/kernel/tracing/dynamic_events
# echo 1 > /sys/kernel/tracing/events/eprobes/open/enable
# cat trace_pipe
cat-1142 [003] ...5. 799.521912: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.521934: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522065: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522080: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522296: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
cat-1142 [003] ...5. 799.522319: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
less-1143 [005] ...5. 799.522327: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522333: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
cat-1142 [003] ...5. 799.522348: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
less-1143 [005] ...5. 799.522349: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522363: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
less-1143 [005] ...5. 799.522477: open: (synthetic.path) file="/etc/ld.so.cache"
cat-1142 [003] ...5. 799.522489: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
less-1143 [005] ...5. 799.522492: open: (synthetic.path) file="/etc/ld.so.cache"
less-1143 [005] ...5. 799.522720: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libtinfo.so.6"
less-1143 [005] ...5. 799.522744: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libtinfo.so.6"
less-1143 [005] ...5. 799.522759: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libtinfo.so.6"
cat-1142 [003] ...5. 799.522850: open: (synthetic.path) file="/lib/x86_64-linux-gnu/libc.so.6"
Link: https://lore.kernel.org/all/20250723124202.4f7475be@batman.local.home/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
The following BPF program, simplified from a syzkaller repro, causes a
kernel warning:
r0 = *(u8 *)(r1 + 169);
exit;
With pointer field sk being at offset 168 in __sk_buff. This access is
detected as a narrower read in bpf_skb_is_valid_access because it
doesn't match offsetof(struct __sk_buff, sk). It is therefore allowed
and later proceeds to bpf_convert_ctx_access. Note that for the
"is_narrower_load" case in the convert_ctx_accesses(), the insn->off
is aligned, so the cnt may not be 0 because it matches the
offsetof(struct __sk_buff, sk) in the bpf_convert_ctx_access. However,
the target_size stays 0 and the verifier errors with a kernel warning:
verifier bug: error during ctx access conversion(1)
This patch fixes that to return a proper "invalid bpf_context access
off=X size=Y" error on the load instruction.
The same issue affects multiple other fields in context structures that
allow narrow access. Some other non-affected fields (for sk_msg,
sk_lookup, and sockopt) were also changed to use bpf_ctx_range_ptr for
consistency.
Note this syzkaller crash was reported in the "Closes" link below, which
used to be about a different bug, fixed in
commit fce7bd8e38 ("bpf/verifier: Handle BPF_LOAD_ACQ instructions
in insn_def_regno()"). Because syzbot somehow confused the two bugs,
the new crash and repro didn't get reported to the mailing list.
Fixes: f96da09473 ("bpf: simplify narrower ctx access")
Fixes: 0df1a55afa ("bpf: Warn on internal verifier errors")
Reported-by: syzbot+0ef84a7bdf5301d4cbec@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0ef84a7bdf5301d4cbec
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/3b8dcee67ff4296903351a974ddd9c4dca768b64.1753194596.git.paul.chaignon@gmail.com
The ipi tracepoints are mostly generic, but the tracepoints ipi_raise,
ipi_entry and ipi_exit are only used by arm and arm64. This means these
trace events are wasting memory in all the other architectures that do not
use them.
Add CONFIG_HAVE_EXTRA_IPI_TRACEPOINTS and have arm and arm64 select it to
enable these trace events. The config makes it easy if other architectures
decide to trace these as well.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Will Deacon <will@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/20250722103714.64eba013@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Since traceprobe_parse_event_name() is a bit complicated, add a
kerneldoc for explaining the behavior.
Link: https://lore.kernel.org/all/175323430565.57270.2602609519355112748.stgit@devnote2/
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Sort the #include directives in trace_probe* files alphabetically for
easier maintenance and avoid double includes.
This also groups headers as linux-generic, asm-generic, and local
headers.
Link: https://lore.kernel.org/all/175323424678.57270.11975372127870059007.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
In January 2015, tracefs was created to allow access to the tracing
infrastructure without needing to compile in debugfs. When tracefs is
configured, the directory /sys/kernel/tracing will exist and tooling is
expected to use that path to access the tracing infrastructure.
To allow backward compatibility, when debugfs is mounted, it would
automount tracefs in its "tracing" directory so that tooling that had hard
coded /sys/kernel/debug/tracing would still work.
It has been over 10 years since the new interface was introduced, and all
tooling should now be using it. Start the process of deprecating the old
path so that it doesn't need to be maintained anymore.
A new config is added to allow distributions to disable automounting of
tracefs on debugfs.
If /sys/kernel/debug/tracing is accessed, a pr_warn() will trigger stating:
"NOTICE: Automounting of tracing to debugfs is deprecated and will be removed in 2030"
Expect to remove this feature in 5 years (2030).
Cc: <linux-trace-users@vger.kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/20250722170806.40c068c6@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Renamed sysctl table from kern_table to sysctl_subsys_table and grouped
the two arch specific ctls to the end of the array.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Moved ctl_tables elements for overflowuid and overflowgid into in
kernel/sys.c. Create a register function that keeps them under "kernel"
and run it after core with postcore_initcall.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move both uevent_helper table into lib/kobject_uevent.c. Place the
registration early in the initcall order with postcore_initcall.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Remove the following headers from the include list in sysctl.c.
* These are removed as the related variables are no longer there.
=================== ====================
Include Related Var
=================== ====================
linux/kmod.h usermodehelper
asm/nmi.h nmi_watchdoc_enabled
asm/io.h io_delay_type
linux/pid.h pid_max_{,min,max}
linux/sched/sysctl.h sysctl_{sched_*,numa_*,timer_*}
linux/mount.h sysctl_mount_max
linux/reboot.h poweroff_cmd
linux/ratelimit.h {,printk_}ratelimit_state
linux/printk.h kptr_restrict
linux/security.h CONFIG_SECURITY_CAPABILITIES
linux/net.h net_table
linux/key.h key_sysctls
linux/nvs_fs.h acpi_video_flags
linux/acpi.h acpi_video_flags
linux/fs.h proc_nr_files
* These are no longer needed as intermediate includes
==============
Include
==============
linux/filter.h
linux/binfmts.h
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
These comments are older than 2003 and therefore do not bare any
relevance on the current state of the sysctl.c file. Remove them as they
confuse more than clarify.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move cad_pid as well as supporting function proc_do_cad_pid into
kernel/pic.c. Replaced call to __do_proc_dointvec with proc_dointvec
inside proc_do_cad_pid which requires the copy of the ctl_table to
handle the temp value.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move the ctl_table with the "tainted" proc_name into kernel/panic.c.
With it moves the proc_tainted helper function.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move both sysrq ctl_table and supported sysrq_sysctl_handler helper
function into drivers/tty/sysrq.c. Replaced the __do_proc_dointvec in
helper function with do_proc_dointvec_minmax as the former is local to
kernel/sysctl.c. Here we use the minmax version of do_proc_dointvec
because do_proc_dointvec is static and calling do_proc_dointvec_minmax
with a NULL min and max is the same as calling do_proc_dointvec.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
make sysctl_max_threads static as it no longer needs to be exported into
sysctl.c.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move the soft-power ctl table into parisc/power.c. As a consequence the
pwrsw_enabled var is made static.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move the randomize_va_space variable together with all its sysctl table
elements into memory.c. Register it to the "kernel" directory by
adding it to the subsys initialization calls
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move sysctl_panic_on_rcu_stall and sysctl_max_rcu_stall_to_panic into
the kernel/rcu subdirectory. Make these static in tree_stall.h and
removed them as extern from panic.h as their scope is now confined into
one file.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move the max_lock_depth sysctl table element into rtmutex_api.c. Removed
the rtmutex.h include from sysctl.c. Chose to move into rtmutex_api.c
to avoid multiple registrations every time rtmutex.c is included in other
files.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Move module sysctl (modprobe_path and modules_disabled) out of sysctl.c
and into the modules subsystem. Make modules_disabled static as it no
longer needs to be exported. Remove module.h from the includes in sysctl
as it no longer uses any module exported variables.
This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Newer compiler versions rightfully point out:
kernel/kcsan/kcsan_test.c:591:41: error: variable 'dummy' is
uninitialized when passed as a const pointer argument here
[-Werror,-Wuninitialized-const-pointer]
591 | KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false);
| ^~~~~
1 error generated.
Although this particular test does not care about the value stored in
the dummy atomic variable, let's silence the warning.
Link: https://lkml.kernel.org/r/CA+G9fYu8JY=k-r0hnBRSkQQrFJ1Bz+ShdXNwC1TNeMt0eXaxeA@mail.gmail.com
Fixes: 8bc32b3481 ("kcsan: test: Add test cases for memory barrier instrumentation")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Reviewed-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Ftrace is tightly coupled with architecture specific code because it
requires the use of trampolines written in assembly. This means that when
a new feature or optimization is made, it must be done for all
architectures. To simplify the approach, CONFIG_HAVE_FTRACE_* configs are
added to denote which architecture has the new enhancement so that other
architectures can still function until they too have been updated.
The CONFIG_HAVE_FTRACE_MCOUNT was added to help simplify the
DYNAMIC_FTRACE work, but now every architecture that implements
DYNAMIC_FTRACE also has HAVE_FTRACE_MCOUNT set too, making it redundant
with the HAVE_DYNAMIC_FTRACE.
Remove the HAVE_FTRACE_MCOUNT config and use DYNAMIC_FTRACE directly where
applicable.
Link: https://lore.kernel.org/all/20250703154916.48e3ada7@gandalf.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250704104838.27a18690@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When soft disabling of trace events was first created, it needed to have a
way to know if a file had a user that was using it with soft disabled (for
triggers that need to enable or disable events from a context that can not
really enable or disable the event, it would set SOFT_DISABLED to state it
is disabled). The flag SOFT_MODE was used to denote that an event had a
user that would enable or disable it via the SOFT_DISABLED flag.
Commit 1cf4c0732d ("tracing: Modify soft-mode only if there's no other
referrer") fixed a bug where if two users were using the SOFT_DISABLED
flag the accounting would get messed up as the SOFT_MODE flag could only
handle one user. That commit added the sm_ref counter which kept track of
how many users were using the event in "soft mode". This made the
SOFT_MODE flag redundant as it should only be set if the sm_ref counter is
non zero.
Remove the SOFT_MODE flag and just use the sm_ref counter to know the
event is in soft mode or not. This makes the code a bit simpler.
Link: https://lore.kernel.org/all/20250702111908.03759998@batman.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Link: https://lore.kernel.org/20250702143657.18dd1882@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Memory barriers are useful to ensure memory accesses from one CPU appear in
the original order as seen by other CPUs.
Some smp_rmb() and smp_wmb() are used, but they are not ordering multiple
memory accesses.
Remove them.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250626151940.1756398-1-namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
ftrace has two flavors:
1) static: Where every function always calls the ftrace trampoline
2) dynamic: Where each function has nops that can be changed on demand to
jump to the ftrace trampoline when needed.
The static flavor has very high performance overhead and was only created
to make it easier for architectures to implement the dynamic flavor. An
architecture developer can first implement the static ftrace to make sure
the trampolines work before working on the more complicated dynamic aspect
of ftrace. Once the architecture can support dynamic ftrace, there's no
reason to continue to support the static flavor. In fact, the static
flavor tends to bitrot and bugs start to appear in them.
Remove the prompt to pick DYNAMIC_FTRACE and simply enable it if the
architecture supports it.
Link: https://lore.kernel.org/all/f7e12c6d-892e-4ca3-9ef0-fbb524d04a48@ghiti.fr/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: ChenMiao <chenmiao.ku@gmail.com>
Link: https://lore.kernel.org/20250703115222.2d7c8cd5@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add a warning if unregister_ftrace_graph() is called without ever
registering it, or if register_ftrace_graph() is called twice. This can
detect errors when they happen and not later when there's a side effect:
Link: https://lore.kernel.org/all/20250617120830.24fbdd62@gandalf.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20250701194451.22e34724@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When the ring buffer was first introduced, reading the non-consuming
"trace" file required disabling the writing of the ring buffer. To make
sure the writing was fully disabled before iterating the buffer with a
non-consuming read, it would set the disable flag of the buffer and then
call an RCU synchronization to make sure all the buffers were
synchronized.
The function ring_buffer_read_start() originally would initialize the
iterator and call an RCU synchronization, but this was for each individual
per CPU buffer where this would get called many times on a machine with
many CPUs before the trace file could be read. The commit 72c9ddfd4c
("ring-buffer: Make non-consuming read less expensive with lots of cpus.")
separated ring_buffer_read_start into ring_buffer_read_prepare(),
ring_buffer_read_sync() and then ring_buffer_read_start() to allow each of
the per CPU buffers to be prepared, call the read_buffer_read_sync() once,
and then the ring_buffer_read_start() for each of the CPUs which made
things much faster.
The commit 1039221cc2 ("ring-buffer: Do not disable recording when there
is an iterator") removed the requirement of disabling the recording of the
ring buffer in order to iterate it, but it did not remove the
synchronization that was happening that was required to wait for all the
buffers to have no more writers. It's now OK for the buffers to have
writers and no synchronization is needed.
Remove the synchronization and put back the interface for the ring buffer
iterator back before commit 72c9ddfd4c was applied.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250630180440.3eabb514@batman.local.home
Reported-by: David Howells <dhowells@redhat.com>
Fixes: 1039221cc2 ("ring-buffer: Do not disable recording when there is an iterator")
Tested-by: David Howells <dhowells@redhat.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
It appears that the defect outlined in 9c15eeb536 ("genirq: Allow
fasteoi handler to resend interrupts on concurrent handling") also
affects some other less stellar MSI controllers, this time using
the handle_simple_irq() flow.
Teach this flow about irqd_needs_resend_when_in_progress(). Given
the invasive nature of this workaround, only this flow is updated.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20250708173404.1278635-2-maz@kernel.org
Yicon reported and Liangyan debugged a live lock in handle_edge_irq()
related to interrupt migration.
If the interrupt affinity is moved to a new target CPU and the interrupt is
currently handled on the previous target CPU for edge type interrupts the
handler might get stuck on the previous target:
CPU 0 (previous target) CPU 1 (new target)
handle_edge_irq()
repeat:
handle_event() handle_edge_irq()
if (INPROGESS) {
set(PENDING);
mask();
return;
}
if (PENDING) {
clear(PENDING);
unmask();
goto repeat;
}
The migration in software never completes and CPU0 continues to handle the
pending events forever. This happens when the device raises interrupts with
a high rate and always before handle_event() completes and before the CPU0
handler can clear INPROGRESS so that CPU1 sets the PENDING flag over and
over. This has been observed in virtual machines.
Prevent this by checking whether the CPU which observes the INPROGRESS flag
is the new affinity target. If that's the case, do not set the PENDING flag
and wait for the INPROGRESS flag to be cleared instead, so that the new
interrupt is handled on the new target CPU and the previous CPU is released
from the action.
This is restricted to the edge type handler and only utilized on systems,
which use single CPU targets for interrupt affinity.
Reported-by: Yicong Shen <shenyicong.1023@bytedance.com>
Reported-by: Liangyan <liangyan.peng@bytedance.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liangyan <liangyan.peng@bytedance.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20250701163558.2588435-1-liangyan.peng@bytedance.com
Link: https://lore.kernel.org/all/20250718185312.076515034@linutronix.de
Let the calling code check for the IRQD_WAKEUP_ARMED flag to prepare for a
live lock mitigation in the edge type handler.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liangyan <liangyan.peng@bytedance.com>
Link: https://lore.kernel.org/all/20250718185312.012392426@linutronix.de
Move it to the call site so that the waiting for the INPROGRESS flag can be
reused by an upcoming mitigation for a potential live lock in the edge type
handler.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liangyan <liangyan.peng@bytedance.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20250718185311.948555026@linutronix.de
The variable is only used at one place, which can simply take the constant
as function argument.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liangyan <liangyan.peng@bytedance.com>
Link: https://lore.kernel.org/all/20250718185311.884314473@linutronix.de
Most drivers only populate the fields cycles and cs_id of system_counterval
in their get_time_fn() callback for get_device_system_crosststamp(), unless
they explicitly provide nanosecond values.
When the use_nsecs field was added to struct system_counterval, most
drivers did not care. Clock sources other than CSID_GENERIC could then get
converted in convert_base_to_cs() based on an uninitialized use_nsecs field,
which usually results in -EINVAL during the following range check.
Pass in a fully zero initialized system_counterval_t to cure that.
Fixes: 6b2e299775 ("timekeeping: Provide infrastructure for converting to/from a base clock")
Signed-off-by: Markus Blöchl <markus@blochl.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250720-timekeeping_uninit_crossts-v2-1-f513c885b7c2@blochl.de
The synchronization of CPU offlining with GP initialization is confusing
to put it mildly (rightfully so as the issue it deals with is complex).
Recent discussions brought up a question -- what prevents the
rcu_implicit_dyntick_qs() from warning about QS reports for offline
CPUs (missing QS reports for offline CPUs causing indefinite hangs).
QS reporting for now-offline CPUs should only happen from:
- gp_init()
- rcutree_cpu_report_dead()
Add some documentation on this and refer to it from comments in the code
explaining how QS reporting is not missed when these functions are
concurrently running.
I referred heavily to this post [1] about the need for the ofl_lock.
[1] https://lore.kernel.org/all/20180924164443.GF4222@linux.ibm.com/
[ Applied paulmck feedback on moving documentation to Requirements.rst ]
Link: https://lore.kernel.org/all/01b4d228-9416-43f8-a62e-124b92e8741a@paulmck-laptop/
Co-developed-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
The details of this are subtle and was discussed recently. Add a
quick-quiz about this and refer to it from the code, for more clarity.
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Add detailed comments explaining the critical ordering constraints
during RCU grace period initialization, based on discussions with
Frederic.
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Co-developed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
To reduce stale data lifetimes, enable CONFIG_INIT_ON_FREE_DEFAULT_ON as
well. This matches the addition of CONFIG_STACKLEAK=y, which is doing
similar for stack memory.
Link: https://lore.kernel.org/r/20250717232519.2984886-13-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
The Clang stack depth tracking implementation has a fixed name for
the stack depth tracking callback, "__sanitizer_cov_stack_depth", so
rename the GCC plugin function to match since the plugin has no external
dependencies on naming.
Link: https://lore.kernel.org/r/20250717232519.2984886-2-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:
- Add the new top-level CONFIG_KSTACK_ERASE option which will be
implemented either with the stackleak GCC plugin, or with the Clang
stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
for what it does rather than what it protects against), but leave as
many of the internals alone as possible to avoid even more churn.
While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Intel linux test robot reported a warning that ERR_CAST can be used
for error pointer casting instead of more-complicated/rarely-used
ERR_PTR(PTR_ERR(...)) style.
There is no functionality change, but still let us replace two such
instances as it improves consistency and readability.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507201048.bceHy8zX-lkp@intel.com/
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20250720164754.3999140-1-yonghong.song@linux.dev
As the trace event powernv_throttle is only used by the powernv code, move
it to a separate include file and have that code directly enable it.
Trace events can take up around 5K of memory when they are defined
regardless if they are used or not. It wastes memory to have them defined
in configurations where the tracepoint is not used.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/20250612145407.906308844@goodmis.org
Fixes: 0306e481d4 ("cpufreq: powernv/tracing: Add powernv_throttle tracepoint")
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
All architectures have an interruptible RCU extended quiescent state
(EQS) as part of their idle sequences, where interrupts can occur
without RCU watching. Entry code must account for this and wake RCU as
necessary; the common entry code deals with this in irqentry_enter() by
treating any interrupt from an idle thread as potentially having
occurred within an EQS and waking RCU for the duration of the interrupt
via rcu_irq_enter() .. rcu_irq_exit().
Some architectures may have other interruptible EQSs which require
similar treatment. For example, on s390 it is necessary to enable
interrupts around guest entry in the middle of a period where core KVM
code has entered an EQS.
So that architectures can wake RCU in these cases, this patch adds a
new arch_in_rcu_eqs() hook to the common entry code which is checked in
addition to the existing is_idle_thread() check, with RCU woken if
either returns true. A default implementation is provided which always
returns false, which suffices for most architectures.
As no architectures currently implement arch_in_rcu_eqs(), there should
be no functional change as a result of this patch alone. A subsequent
patch will add an s390 implementation to fix a latent bug with missing
RCU wakeups.
[ajd@linux.ibm.com: rebase, fix commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20250708092742.104309-2-ajd@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20250708092742.104309-2-ajd@linux.ibm.com>
- Fix timerlat with use of FORTIFY_SOURCE
FORTIFY_SOURCE was added to the stack tracer where it compares the
entry->caller array to having entry->size elements.
timerlat has the following:
memcpy(&entry->caller, fstack->calls, size);
entry->size = size;
Which triggers FORTIFY_SOURCE as the caller is populated before the
entry->size is initialized.
Swap the order to satisfy FORTIFY_SOURCE logic.
- Add down_write(trace_event_sem) when adding trace events in modules
Trace events being added to the ftrace_events array are protected by
the trace_event_sem semaphore. But when loading modules that have
trace events, the addition of the events are not protected by the
semaphore and loading two modules that have events at the same time
can corrupt the list.
Also add a lockdep_assert_held(trace_event_sem) to
_trace_add_event_dirs() to confirm its held when iterating the list.
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Merge tag 'trace-v6.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix timerlat with use of FORTIFY_SOURCE
FORTIFY_SOURCE was added to the stack tracer where it compares the
entry->caller array to having entry->size elements.
timerlat has the following:
memcpy(&entry->caller, fstack->calls, size);
entry->size = size;
Which triggers FORTIFY_SOURCE as the caller is populated before the
entry->size is initialized.
Swap the order to satisfy FORTIFY_SOURCE logic.
- Add down_write(trace_event_sem) when adding trace events in modules
Trace events being added to the ftrace_events array are protected by
the trace_event_sem semaphore. But when loading modules that have
trace events, the addition of the events are not protected by the
semaphore and loading two modules that have events at the same time
can corrupt the list.
Also add a lockdep_assert_held(trace_event_sem) to
_trace_add_event_dirs() to confirm it is held when iterating the
list.
* tag 'trace-v6.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Add down_write(trace_event_sem) when adding trace event
tracing/osnoise: Fix crash in timerlat_dump_stack()
counter nr_uninterruptible to an unsigned int. Due to the fact that the
counters are not updated on migration of a uninterruptble task to a
different CPU, these counters can exceed INT_MAX. The counter is cast to
long in the load average calculation, which means that the cast expands
into negative space resulting in bogus load average values. Convert it back
to unsigned long to fix this.
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Merge tag 'sched-urgent-2025-07-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Thomas Gleixner:
"A single fix for the scheduler.
A recent commit changed the runqueue counter nr_uninterruptible to an
unsigned int. Due to the fact that the counters are not updated on
migration of a uninterruptble task to a different CPU, these counters
can exceed INT_MAX.
The counter is cast to long in the load average calculation, which
means that the cast expands into negative space resulting in bogus
load average values.
Convert it back to unsigned long to fix this.
* tag 'sched-urgent-2025-07-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Change nr_uninterruptible type to unsigned long
Inspired by mutex blocker tracking[1], and having already extended it to
semaphores, let's now add support for reader-writer semaphores (rwsems).
The approach is simple: when a task enters TASK_UNINTERRUPTIBLE while
waiting for an rwsem, we just call hung_task_set_blocker(). The hung task
detector can then query the rwsem's owner to identify the lock holder.
Tracking works reliably for writers, as there can only be a single writer
holding the lock, and its task struct is stored in the owner field.
The main challenge lies with readers. The owner field points to only one
of many concurrent readers, so we might lose track of the blocker if that
specific reader unlocks, even while others remain. This is not a
significant issue, however. In practice, long-lasting lock contention is
almost always caused by a writer. Therefore, reliably tracking the writer
is the primary goal of this patch series ;)
With this change, the hung task detector can now show blocker task's info
like below:
[Fri Jun 27 15:21:34 2025] INFO: task cat:28631 blocked for more than 122 seconds.
[Fri Jun 27 15:21:34 2025] Tainted: G S 6.16.0-rc3 #8
[Fri Jun 27 15:21:34 2025] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Fri Jun 27 15:21:34 2025] task:cat state:D stack:0 pid:28631 tgid:28631 ppid:28501 task_flags:0x400000 flags:0x00004000
[Fri Jun 27 15:21:34 2025] Call Trace:
[Fri Jun 27 15:21:34 2025] <TASK>
[Fri Jun 27 15:21:34 2025] __schedule+0x7c7/0x1930
[Fri Jun 27 15:21:34 2025] ? __pfx___schedule+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? policy_nodemask+0x215/0x340
[Fri Jun 27 15:21:34 2025] ? _raw_spin_lock_irq+0x8a/0xe0
[Fri Jun 27 15:21:34 2025] ? __pfx__raw_spin_lock_irq+0x10/0x10
[Fri Jun 27 15:21:34 2025] schedule+0x6a/0x180
[Fri Jun 27 15:21:34 2025] schedule_preempt_disabled+0x15/0x30
[Fri Jun 27 15:21:34 2025] rwsem_down_read_slowpath+0x55e/0xe10
[Fri Jun 27 15:21:34 2025] ? __pfx_rwsem_down_read_slowpath+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __pfx___might_resched+0x10/0x10
[Fri Jun 27 15:21:34 2025] down_read+0xc9/0x230
[Fri Jun 27 15:21:34 2025] ? __pfx_down_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __debugfs_file_get+0x14d/0x700
[Fri Jun 27 15:21:34 2025] ? __pfx___debugfs_file_get+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? handle_pte_fault+0x52a/0x710
[Fri Jun 27 15:21:34 2025] ? selinux_file_permission+0x3a9/0x590
[Fri Jun 27 15:21:34 2025] read_dummy_rwsem_read+0x4a/0x90
[Fri Jun 27 15:21:34 2025] full_proxy_read+0xff/0x1c0
[Fri Jun 27 15:21:34 2025] ? rw_verify_area+0x6d/0x410
[Fri Jun 27 15:21:34 2025] vfs_read+0x177/0xa50
[Fri Jun 27 15:21:34 2025] ? __pfx_vfs_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? fdget_pos+0x1cf/0x4c0
[Fri Jun 27 15:21:34 2025] ksys_read+0xfc/0x1d0
[Fri Jun 27 15:21:34 2025] ? __pfx_ksys_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] do_syscall_64+0x66/0x2d0
[Fri Jun 27 15:21:34 2025] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[Fri Jun 27 15:21:34 2025] RIP: 0033:0x7f3f8faefb40
[Fri Jun 27 15:21:34 2025] RSP: 002b:00007ffdeda5ab98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[Fri Jun 27 15:21:34 2025] RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 00007f3f8faefb40
[Fri Jun 27 15:21:34 2025] RDX: 0000000000010000 RSI: 00000000010fa000 RDI: 0000000000000003
[Fri Jun 27 15:21:34 2025] RBP: 00000000010fa000 R08: 0000000000000000 R09: 0000000000010fff
[Fri Jun 27 15:21:34 2025] R10: 00007ffdeda59fe0 R11: 0000000000000246 R12: 00000000010fa000
[Fri Jun 27 15:21:34 2025] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[Fri Jun 27 15:21:34 2025] </TASK>
[Fri Jun 27 15:21:34 2025] INFO: task cat:28631 <reader> blocked on an rw-semaphore likely owned by task cat:28630 <writer>
[Fri Jun 27 15:21:34 2025] task:cat state:S stack:0 pid:28630 tgid:28630 ppid:28501 task_flags:0x400000 flags:0x00004000
[Fri Jun 27 15:21:34 2025] Call Trace:
[Fri Jun 27 15:21:34 2025] <TASK>
[Fri Jun 27 15:21:34 2025] __schedule+0x7c7/0x1930
[Fri Jun 27 15:21:34 2025] ? __pfx___schedule+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __mod_timer+0x304/0xa80
[Fri Jun 27 15:21:34 2025] schedule+0x6a/0x180
[Fri Jun 27 15:21:34 2025] schedule_timeout+0xfb/0x230
[Fri Jun 27 15:21:34 2025] ? __pfx_schedule_timeout+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __pfx_process_timeout+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? down_write+0xc4/0x140
[Fri Jun 27 15:21:34 2025] msleep_interruptible+0xbe/0x150
[Fri Jun 27 15:21:34 2025] read_dummy_rwsem_write+0x54/0x90
[Fri Jun 27 15:21:34 2025] full_proxy_read+0xff/0x1c0
[Fri Jun 27 15:21:34 2025] ? rw_verify_area+0x6d/0x410
[Fri Jun 27 15:21:34 2025] vfs_read+0x177/0xa50
[Fri Jun 27 15:21:34 2025] ? __pfx_vfs_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? fdget_pos+0x1cf/0x4c0
[Fri Jun 27 15:21:34 2025] ksys_read+0xfc/0x1d0
[Fri Jun 27 15:21:34 2025] ? __pfx_ksys_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] do_syscall_64+0x66/0x2d0
[Fri Jun 27 15:21:34 2025] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[Fri Jun 27 15:21:34 2025] RIP: 0033:0x7f8f288efb40
[Fri Jun 27 15:21:34 2025] RSP: 002b:00007ffffb631038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[Fri Jun 27 15:21:34 2025] RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 00007f8f288efb40
[Fri Jun 27 15:21:34 2025] RDX: 0000000000010000 RSI: 000000002a4b5000 RDI: 0000000000000003
[Fri Jun 27 15:21:34 2025] RBP: 000000002a4b5000 R08: 0000000000000000 R09: 0000000000010fff
[Fri Jun 27 15:21:34 2025] R10: 00007ffffb630460 R11: 0000000000000246 R12: 000000002a4b5000
[Fri Jun 27 15:21:34 2025] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[Fri Jun 27 15:21:34 2025] </TASK>
[1] https://lore.kernel.org/all/174046694331.2194069.15472952050240807469.stgit@mhiramat.tok.corp.google.com/
Link: https://lkml.kernel.org/r/20250627072924.36567-3-lance.yang@linux.dev
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Stultz <jstultz@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Mingzhe Yang <mingzhe.yang@ly.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yongliang Gao <leonylgao@tencent.com>
Cc: Zi Li <zi.li@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "extend hung task blocker tracking to rwsems".
Inspired by mutex blocker tracking[1], and having already extended it to
semaphores, let's now add support for reader-writer semaphores (rwsems).
The approach is simple: when a task enters TASK_UNINTERRUPTIBLE while
waiting for an rwsem, we just call hung_task_set_blocker(). The hung task
detector can then query the rwsem's owner to identify the lock holder.
Tracking works reliably for writers, as there can only be a single writer
holding the lock, and its task struct is stored in the owner field.
The main challenge lies with readers. The owner field points to only one
of many concurrent readers, so we might lose track of the blocker if that
specific reader unlocks, even while others remain. This is not a
significant issue, however. In practice, long-lasting lock contention is
almost always caused by a writer. Therefore, reliably tracking the writer
is the primary goal of this patch series ;)
With this change, the hung task detector can now show blocker task's info
like below:
[Fri Jun 27 15:21:34 2025] INFO: task cat:28631 blocked for more than 122 seconds.
[Fri Jun 27 15:21:34 2025] Tainted: G S 6.16.0-rc3 #8
[Fri Jun 27 15:21:34 2025] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Fri Jun 27 15:21:34 2025] task:cat state:D stack:0 pid:28631 tgid:28631 ppid:28501 task_flags:0x400000 flags:0x00004000
[Fri Jun 27 15:21:34 2025] Call Trace:
[Fri Jun 27 15:21:34 2025] <TASK>
[Fri Jun 27 15:21:34 2025] __schedule+0x7c7/0x1930
[Fri Jun 27 15:21:34 2025] ? __pfx___schedule+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? policy_nodemask+0x215/0x340
[Fri Jun 27 15:21:34 2025] ? _raw_spin_lock_irq+0x8a/0xe0
[Fri Jun 27 15:21:34 2025] ? __pfx__raw_spin_lock_irq+0x10/0x10
[Fri Jun 27 15:21:34 2025] schedule+0x6a/0x180
[Fri Jun 27 15:21:34 2025] schedule_preempt_disabled+0x15/0x30
[Fri Jun 27 15:21:34 2025] rwsem_down_read_slowpath+0x55e/0xe10
[Fri Jun 27 15:21:34 2025] ? __pfx_rwsem_down_read_slowpath+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __pfx___might_resched+0x10/0x10
[Fri Jun 27 15:21:34 2025] down_read+0xc9/0x230
[Fri Jun 27 15:21:34 2025] ? __pfx_down_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __debugfs_file_get+0x14d/0x700
[Fri Jun 27 15:21:34 2025] ? __pfx___debugfs_file_get+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? handle_pte_fault+0x52a/0x710
[Fri Jun 27 15:21:34 2025] ? selinux_file_permission+0x3a9/0x590
[Fri Jun 27 15:21:34 2025] read_dummy_rwsem_read+0x4a/0x90
[Fri Jun 27 15:21:34 2025] full_proxy_read+0xff/0x1c0
[Fri Jun 27 15:21:34 2025] ? rw_verify_area+0x6d/0x410
[Fri Jun 27 15:21:34 2025] vfs_read+0x177/0xa50
[Fri Jun 27 15:21:34 2025] ? __pfx_vfs_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? fdget_pos+0x1cf/0x4c0
[Fri Jun 27 15:21:34 2025] ksys_read+0xfc/0x1d0
[Fri Jun 27 15:21:34 2025] ? __pfx_ksys_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] do_syscall_64+0x66/0x2d0
[Fri Jun 27 15:21:34 2025] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[Fri Jun 27 15:21:34 2025] RIP: 0033:0x7f3f8faefb40
[Fri Jun 27 15:21:34 2025] RSP: 002b:00007ffdeda5ab98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[Fri Jun 27 15:21:34 2025] RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 00007f3f8faefb40
[Fri Jun 27 15:21:34 2025] RDX: 0000000000010000 RSI: 00000000010fa000 RDI: 0000000000000003
[Fri Jun 27 15:21:34 2025] RBP: 00000000010fa000 R08: 0000000000000000 R09: 0000000000010fff
[Fri Jun 27 15:21:34 2025] R10: 00007ffdeda59fe0 R11: 0000000000000246 R12: 00000000010fa000
[Fri Jun 27 15:21:34 2025] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[Fri Jun 27 15:21:34 2025] </TASK>
[Fri Jun 27 15:21:34 2025] INFO: task cat:28631 <reader> blocked on an rw-semaphore likely owned by task cat:28630 <writer>
[Fri Jun 27 15:21:34 2025] task:cat state:S stack:0 pid:28630 tgid:28630 ppid:28501 task_flags:0x400000 flags:0x00004000
[Fri Jun 27 15:21:34 2025] Call Trace:
[Fri Jun 27 15:21:34 2025] <TASK>
[Fri Jun 27 15:21:34 2025] __schedule+0x7c7/0x1930
[Fri Jun 27 15:21:34 2025] ? __pfx___schedule+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __mod_timer+0x304/0xa80
[Fri Jun 27 15:21:34 2025] schedule+0x6a/0x180
[Fri Jun 27 15:21:34 2025] schedule_timeout+0xfb/0x230
[Fri Jun 27 15:21:34 2025] ? __pfx_schedule_timeout+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? __pfx_process_timeout+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? down_write+0xc4/0x140
[Fri Jun 27 15:21:34 2025] msleep_interruptible+0xbe/0x150
[Fri Jun 27 15:21:34 2025] read_dummy_rwsem_write+0x54/0x90
[Fri Jun 27 15:21:34 2025] full_proxy_read+0xff/0x1c0
[Fri Jun 27 15:21:34 2025] ? rw_verify_area+0x6d/0x410
[Fri Jun 27 15:21:34 2025] vfs_read+0x177/0xa50
[Fri Jun 27 15:21:34 2025] ? __pfx_vfs_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] ? fdget_pos+0x1cf/0x4c0
[Fri Jun 27 15:21:34 2025] ksys_read+0xfc/0x1d0
[Fri Jun 27 15:21:34 2025] ? __pfx_ksys_read+0x10/0x10
[Fri Jun 27 15:21:34 2025] do_syscall_64+0x66/0x2d0
[Fri Jun 27 15:21:34 2025] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[Fri Jun 27 15:21:34 2025] RIP: 0033:0x7f8f288efb40
[Fri Jun 27 15:21:34 2025] RSP: 002b:00007ffffb631038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[Fri Jun 27 15:21:34 2025] RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 00007f8f288efb40
[Fri Jun 27 15:21:34 2025] RDX: 0000000000010000 RSI: 000000002a4b5000 RDI: 0000000000000003
[Fri Jun 27 15:21:34 2025] RBP: 000000002a4b5000 R08: 0000000000000000 R09: 0000000000010fff
[Fri Jun 27 15:21:34 2025] R10: 00007ffffb630460 R11: 0000000000000246 R12: 000000002a4b5000
[Fri Jun 27 15:21:34 2025] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff
[Fri Jun 27 15:21:34 2025] </TASK>
This patch (of 3):
In preparation for extending blocker tracking to support rwsems, make the
rwsem_owner() and is_rwsem_reader_owned() helpers globally available for
determining if the blocker is a writer or one of the readers.
Additionally, a stale owner pointer in a reader-owned rwsem can lead to
false positives in blocker tracking when CONFIG_DETECT_HUNG_TASK_BLOCKER
is enabled. To mitigate this, clear the owner field on the reader unlock
path, similar to what CONFIG_DEBUG_RWSEMS does. A NULL owner is better
than a stale one for diagnostics.
Link: https://lkml.kernel.org/r/20250627072924.36567-1-lance.yang@linux.dev
Link: https://lkml.kernel.org/r/20250627072924.36567-2-lance.yang@linux.dev
Link: https://lore.kernel.org/all/174046694331.2194069.15472952050240807469.stgit@mhiramat.tok.corp.google.com/ [1]
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Stultz <jstultz@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Mingzhe Yang <mingzhe.yang@ly.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yongliang Gao <leonylgao@tencent.com>
Cc: Zi Li <zi.li@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a dedicated core parameter 'panic_console_replay' for controlling
console replay, and add note that 'panic_print' sysctl interface will be
obsoleted by 'panic_sys_info' and 'panic_console_replay'. When it
happens, the SYS_INFO_PANIC_CONSOLE_REPLAY can be removed as well.
Link: https://lkml.kernel.org/r/20250703021004.42328-6-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Bitmap definition for 'panic_print' is hard to remember and decode. Add
'panic_sys_info='sysctl to take human readable string like
"tasks,mem,timers,locks,ftrace,..." and translate it into bitmap.
The detailed mapping is:
SYS_INFO_TASKS "tasks"
SYS_INFO_MEM "mem"
SYS_INFO_TIMERS "timers"
SYS_INFO_LOCKS "locks"
SYS_INFO_FTRACE "ftrace"
SYS_INFO_ALL_CPU_BT "all_bt"
SYS_INFO_BLOCKED_TASKS "blocked_tasks"
[nathan@kernel.org: add __maybe_unused to sys_info_avail]
Link: https://lkml.kernel.org/r/20250708-fix-clang-sys_info_avail-warning-v1-1-60d239eacd64@kernel.org
Link: https://lkml.kernel.org/r/20250703021004.42328-4-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
'panic_print' was introduced to help debugging kernel panic by dumping
different kinds of system information like tasks' call stack, memory,
ftrace buffer, etc. Actually this function could also be used to help
debugging other cases like task-hung, soft/hard lockup, etc. where user
may need the snapshot of system info at that time.
Extract system info dump function related code from panic.c to separate
file sys_info.[ch], for wider usage by other kernel parts for debugging.
Also modify the macro names about singulars/plurals.
Link: https://lkml.kernel.org/r/20250703021004.42328-3-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "generalize panic_print's dump function to be used by other
kernel parts", v3.
When working on kernel stability issues, panic, task-hung and
software/hardware lockup are frequently met. And to debug them, user may
need lots of system information at that time, like task call stacks, lock
info, memory info etc.
panic case already has panic_print_sys_info() for this purpose, and has a
'panic_print' bitmask to control what kinds of information is needed,
which is also helpful to debug other task-hung and lockup cases.
So this patchset extracts the function out to a new file 'lib/sys_info.c',
and makes it available for other cases which also need to dump system info
for debugging.
Also as suggested by Petr Mladek, add 'panic_sys_info=' interface to take
human readable string like "tasks,mem,locks,timers,ftrace,....", and
eventually obsolete the current 'panic_print' bitmap interface.
In RFC and V1 version, hung_task and SW/HW watchdog modules are enabled
with the new sys_info dump interface. In v2, they are kept out for better
review of current change, and will be posted later.
Locally these have been used in our bug chasing for stability issues and
was proven helpful.
Many thanks to Petr Mladek for great suggestions on both the code and
architectures!
This patch (of 5):
Currently the panic_print_sys_info() was called twice with different
parameters to handle console replay case, which is kind of confusing.
Add panic_console_replay() explicitly and rename
'PANIC_PRINT_ALL_PRINTK_MSG' to 'PANIC_CONSOLE_REPLAY', to make the code
straightforward. The related kernel document is also updated.
Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20250703021004.42328-2-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When re-using the CMA area for kdump there is a risk of pending DMA into
pinned user pages in the CMA area.
Pages residing in CMA areas can usually not get long-term pinned and are
instead migrated away from the CMA area, so long-term pinning is typically
not a concern. (BUGs in the kernel might still lead to long-term pinning
of such pages if everything goes wrong.)
Pages pinned without FOLL_LONGTERM remain in the CMA and may possibly be
the source or destination of a pending DMA transfer.
Although there is no clear specification how long a page may be pinned
without FOLL_LONGTERM, pinning without the flag shows an intent of the
caller to only use the memory for short-lived DMA transfers, not a
transfer initiated by a device asynchronously at a random time in the
future.
Add a delay of CMA_DMA_TIMEOUT_SEC seconds before starting the kdump
kernel, giving such short-lived DMA transfers time to finish before the
CMA memory is re-used by the kdump kernel.
Set CMA_DMA_TIMEOUT_SEC to 10 seconds - chosen arbitrarily as both a huge
margin for a DMA transfer, yet not increasing the kdump time too
significantly.
Link: https://lkml.kernel.org/r/aEqpgDIBndZ5LXSo@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
reserve_crashkernel_cma() reserves CMA ranges for the crash kernel. If
allocating the requested size fails, try to reserve in smaller blocks.
Store the reserved ranges in the crashk_cma_ranges array and the number of
ranges in crashk_cma_cnt.
Link: https://lkml.kernel.org/r/aEqpBwOy_ekm0gw9@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "kdump: crashkernel reservation from CMA", v5.
This series implements a way to reserve additional crash kernel memory
using CMA.
Currently, all the memory for the crash kernel is not usable by the 1st
(production) kernel. It is also unmapped so that it can't be corrupted by
the fault that will eventually trigger the crash. This makes sense for
the memory actually used by the kexec-loaded crash kernel image and initrd
and the data prepared during the load (vmcoreinfo, ...). However, the
reserved space needs to be much larger than that to provide enough
run-time memory for the crash kernel and the kdump userspace. Estimating
the amount of memory to reserve is difficult. Being too careful makes
kdump likely to end in OOM, being too generous takes even more memory from
the production system. Also, the reservation only allows reserving a
single contiguous block (or two with the "low" suffix). I've seen systems
where this fails because the physical memory is fragmented.
By reserving additional crashkernel memory from CMA, the main crashkernel
reservation can be just large enough to fit the kernel and initrd image,
minimizing the memory taken away from the production system. Most of the
run-time memory for the crash kernel will be memory previously available
to userspace in the production system. As this memory is no longer
wasted, the reservation can be done with a generous margin, making kdump
more reliable. Kernel memory that we need to preserve for dumping is
normally not allocated from CMA, unless it is explicitly allocated as
movable. Currently this is only the case for memory ballooning and zswap.
Such movable memory will be missing from the vmcore. User data is
typically not dumped by makedumpfile. When dumping of user data is
intended this new CMA reservation cannot be used.
There are five patches in this series:
The first adds a new ",cma" suffix to the recenly introduced generic
crashkernel parsing code. parse_crashkernel() takes one more argument to
store the cma reservation size.
The second patch implements reserve_crashkernel_cma() which performs the
reservation. If the requested size is not available in a single range,
multiple smaller ranges will be reserved.
The third patch updates Documentation/, explicitly mentioning the
potential DMA corruption of the CMA-reserved memory.
The fourth patch adds a short delay before booting the kdump kernel,
allowing pending DMA transfers to finish.
The fifth patch enables the functionality for x86 as a proof of
concept. There are just three things every arch needs to do:
- call reserve_crashkernel_cma()
- include the CMA-reserved ranges in the physical memory map
- exclude the CMA-reserved ranges from the memory available
through /proc/vmcore by excluding them from the vmcoreinfo
PT_LOAD ranges.
Adding other architectures is easy and I can do that as soon as this
series is merged.
With this series applied, specifying
crashkernel=100M craskhernel=1G,cma
on the command line will make a standard crashkernel reservation
of 100M, where kexec will load the kernel and initrd.
An additional 1G will be reserved from CMA, still usable by the production
system. The crash kernel will have 1.1G memory available. The 100M can
be reliably predicted based on the size of the kernel and initrd.
The new cma suffix is completely optional. When no
crashkernel=size,cma is specified, everything works as before.
This patch (of 5):
Add a new cma_size parameter to parse_crashkernel(). When not NULL, call
__parse_crashkernel to parse the CMA reservation size from
"crashkernel=size,cma" and store it in cma_size.
Set cma_size to NULL in all calls to parse_crashkernel().
Link: https://lkml.kernel.org/r/aEqnxxfLZMllMC8I@dwarf.suse.cz
Link: https://lkml.kernel.org/r/aEqoQckgoTQNULnh@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When a module is loaded, it adds trace events defined by the module. It
may also need to modify the modules trace printk formats to replace enum
names with their values.
If two modules are loaded at the same time, the adding of the event to the
ftrace_events list can corrupt the walking of the list in the code that is
modifying the printk format strings and crash the kernel.
The addition of the event should take the trace_event_sem for write while
it adds the new event.
Also add a lockdep_assert_held() on that semaphore in
__trace_add_event_dirs() as it iterates the list.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/20250718223158.799bfc0c@batman.local.home
Reported-by: Fusheng Huang(黄富生) <Fusheng.Huang@luxshare-ict.com>
Closes: https://lore.kernel.org/all/20250717105007.46ccd18f@batman.local.home/
Fixes: 110bf2b764 ("tracing: add protection around module events unload")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
- Fix handling of migration disabled tasks in default idle selection.
- update_locked_rq() called __this_cpu_write() spuriously with NULL when @rq
was not locked. As the writes were spurious, it didn't break anything
directly. However, the function could be called in a preemptible leading
to a context warning in __this_cpu_write(). Skip the spurious NULL writes.
- Selftest fix on UP.
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Merge tag 'sched_ext-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Fix handling of migration disabled tasks in default idle selection
- update_locked_rq() called __this_cpu_write() spuriously with NULL
when @rq was not locked. As the writes were spurious, it didn't break
anything directly. However, the function could be called in a
preemptible leading to a context warning in __this_cpu_write(). Skip
the spurious NULL writes.
- Selftest fix on UP
* tag 'sched_ext-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: idle: Handle migration-disabled tasks in idle selection
sched/ext: Prevent update_locked_rq() calls with NULL rq
selftests/sched_ext: Fix exit selftest hang on UP
An earlier commit to suppress a warning introduced a race condition where
tasks can escape cgroup1 freezer. Revert the commit and simply remove the
warning which was spurious to begin with.
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Merge tag 'cgroup-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"An earlier commit to suppress a warning introduced a race condition
where tasks can escape cgroup1 freezer. Revert the commit and simply
remove the warning which was spurious to begin with"
* tag 'cgroup-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"
sched,freezer: Remove unnecessary warning in __thaw_task
/proc/cgroups lists only v1 controllers by default, however, this is
only enforced since the commit af000ce852 ("cgroup: Do not report
unavailable v1 controllers in /proc/cgroups") and there is software in
the wild that uses content of /proc/cgroups to decide on availability of
v2 (sic) controllers.
Add a boottime param that can bring back the previous behavior for
setups where the check in the software cannot be changed and it causes
e.g. unintended OOMs.
Also, this patch takes out cgrp_v1_visible from cgroup1_subsys_absent()
guard since it's only important to check which hierarchy (v1 vs v2) the
subsys is attached to. This has no effect on the printed message but
the code is cleaner since cgrp_v1_visible is really about mounted
hierarchies, not the content of /proc/cgroups.
Link: https://lore.kernel.org/r/b26b60b7d0d2a5ecfd2f3c45f95f32922ed24686.camel@decadent.org.uk
Fixes: af000ce852 ("cgroup: Do not report unavailable v1 controllers in /proc/cgroups")
Fixes: a0ab145322 ("cgroup: Print message when /proc/cgroups is read on v2-only system")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
We have observed kernel panics when using timerlat with stack saving,
with the following dmesg output:
memcpy: detected buffer overflow: 88 byte write of buffer size 0
WARNING: CPU: 2 PID: 8153 at lib/string_helpers.c:1032 __fortify_report+0x55/0xa0
CPU: 2 UID: 0 PID: 8153 Comm: timerlatu/2 Kdump: loaded Not tainted 6.15.3-200.fc42.x86_64 #1 PREEMPT(lazy)
Call Trace:
<TASK>
? trace_buffer_lock_reserve+0x2a/0x60
__fortify_panic+0xd/0xf
__timerlat_dump_stack.cold+0xd/0xd
timerlat_dump_stack.part.0+0x47/0x80
timerlat_fd_read+0x36d/0x390
vfs_read+0xe2/0x390
? syscall_exit_to_user_mode+0x1d5/0x210
ksys_read+0x73/0xe0
do_syscall_64+0x7b/0x160
? exc_page_fault+0x7e/0x1a0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
__timerlat_dump_stack() constructs the ftrace stack entry like this:
struct stack_entry *entry;
...
memcpy(&entry->caller, fstack->calls, size);
entry->size = fstack->nr_entries;
Since commit e7186af7fb ("tracing: Add back FORTIFY_SOURCE logic to
kernel_stack event structure"), struct stack_entry marks its caller
field with __counted_by(size). At the time of the memcpy, entry->size
contains garbage from the ringbuffer, which under some circumstances is
zero, triggering a kernel panic by buffer overflow.
Populate the size field before the memcpy so that the out-of-bounds
check knows the correct size. This is analogous to
__ftrace_trace_stack().
Cc: stable@vger.kernel.org
Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Attila Fazekas <afazekas@redhat.com>
Link: https://lore.kernel.org/20250716143601.7313-1-tglozar@redhat.com
Fixes: e7186af7fb ("tracing: Add back FORTIFY_SOURCE logic to kernel_stack event structure")
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Alexei Starovoitov:
- Fix handling of BPF arena relocations (Andrii Nakryiko)
- Fix race in bpf_arch_text_poke() on s390 (Ilya Leoshkevich)
- Fix use of virt_to_phys() on arm64 when mmapping BTF (Lorenz Bauer)
- Reject %p% format string in bprintf-like BPF helpers (Paul Chaignon)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
libbpf: Fix handling of BPF arena relocations
btf: Fix virt_to_phys() on arm64 when mmapping BTF
selftests/bpf: Stress test attaching a BPF prog to another BPF prog
s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL again
selftests/bpf: Add negative test cases for snprintf
bpf: Reject %p% format string in bprintf-like helpers
Expose the auxiliary clock data so it can be read from the vDSO.
Architectures not using the generic vDSO time framework,
namely SPARC64, are not supported.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-11-df7d9f87b9b8@linutronix.de
We observed a regression in our customer’s environment after enabling
CONFIG_LAZY_RCU. In the Android Update Engine scenario, where ioctl() is
used heavily, we found that callbacks queued via call_rcu_hurry (such as
percpu_ref_switch_to_atomic_rcu) can sometimes be delayed by up to 5
seconds before execution. This occurs because the new grace period does
not start immediately after the previous one completes.
The root cause is that the wake_nocb_gp_defer() function now checks
"rdp->nocb_defer_wakeup" instead of "rdp_gp->nocb_defer_wakeup". On CPUs
that are not rcuog, "rdp->nocb_defer_wakeup" may always be
RCU_NOCB_WAKE_NOT. This can cause "rdp_gp->nocb_defer_wakeup" to be
downgraded and the "rdp_gp->nocb_timer" to be postponed by up to 10
seconds, delaying the execution of hurry RCU callbacks.
The trace log of one scenario we encountered is as follow:
// previous GP ends at this point
rcu_preempt [000] d..1. 137.240210: rcu_grace_period: rcu_preempt 8369 end
rcu_preempt [000] ..... 137.240212: rcu_grace_period: rcu_preempt 8372 reqwait
// call_rcu_hurry enqueues "percpu_ref_switch_to_atomic_rcu", the callback waited on by UpdateEngine
update_engine [002] d..1. 137.301593: __call_rcu_common: wyy: unlikely p_ref = 00000000********. lazy = 0
// FirstQ on cpu 2 rdp_gp->nocb_timer is set to fire after 1 jiffy (4ms)
// and the rdp_gp->nocb_defer_wakeup is set to RCU_NOCB_WAKE
update_engine [002] d..2. 137.301595: rcu_nocb_wake: rcu_preempt 2 FirstQ on cpu2 with rdp_gp (cpu0).
// FirstBQ event on cpu2 during the 1 jiffy, make the timer postpond 10 seconds later.
// also, the rdp_gp->nocb_defer_wakeup is overwrite to RCU_NOCB_WAKE_LAZY
update_engine [002] d..1. 137.301601: rcu_nocb_wake: rcu_preempt 2 WakeEmptyIsDeferred
...
...
...
// before the 10 seconds timeout, cpu0 received another call_rcu_hurry
// reset the timer to jiffies+1 and set the waketype = RCU_NOCB_WAKE.
kworker/u32:0 [000] d..2. 142.557564: rcu_nocb_wake: rcu_preempt 0 FirstQ
kworker/u32:0 [000] d..1. 142.557576: rcu_nocb_wake: rcu_preempt 0 WakeEmptyIsDeferred
kworker/u32:0 [000] d..1. 142.558296: rcu_nocb_wake: rcu_preempt 0 WakeNot
kworker/u32:0 [000] d..1. 142.558562: rcu_nocb_wake: rcu_preempt 0 WakeNot
// idle(do_nocb_deferred_wakeup) wake rcuog due to waketype == RCU_NOCB_WAKE
<idle> [000] d..1. 142.558786: rcu_nocb_wake: rcu_preempt 0 DoWake
<idle> [000] dN.1. 142.558839: rcu_nocb_wake: rcu_preempt 0 DeferredWake
rcuog/0 [000] ..... 142.558871: rcu_nocb_wake: rcu_preempt 0 EndSleep
rcuog/0 [000] ..... 142.558877: rcu_nocb_wake: rcu_preempt 0 Check
// finally rcuog request a new GP at this point (5 seconds after the FirstQ event)
rcuog/0 [000] d..2. 142.558886: rcu_grace_period: rcu_preempt 8372 newreq
rcu_preempt [001] d..1. 142.559458: rcu_grace_period: rcu_preempt 8373 start
...
rcu_preempt [000] d..1. 142.564258: rcu_grace_period: rcu_preempt 8373 end
rcuop/2 [000] D..1. 142.566337: rcu_batch_start: rcu_preempt CBs=219 bl=10
// the hurry CB is invoked at this point
rcuop/2 [000] b.... 142.566352: blk_queue_usage_counter_release: wyy: wakeup. p_ref = 00000000********.
This patch changes the condition to check "rdp_gp->nocb_defer_wakeup" in
the lazy path. This prevents an already scheduled "rdp_gp->nocb_timer"
from being postponed and avoids overwriting "rdp_gp->nocb_defer_wakeup"
when it is not RCU_NOCB_WAKE_NOT.
Fixes: 3cb278e73b ("rcu: Make call_rcu() lazy to save power")
Co-developed-by: Cheng-jui Wang <cheng-jui.wang@mediatek.com>
Signed-off-by: Cheng-jui Wang <cheng-jui.wang@mediatek.com>
Co-developed-by: Lorry.Luo@mediatek.com
Signed-off-by: Lorry.Luo@mediatek.com
Tested-by: weiyangyang@vivo.com
Signed-off-by: weiyangyang@vivo.com
Signed-off-by: Tze-nan Wu <Tze-nan.Wu@mediatek.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Change the order of function qualifiers from 'noinline static' to 'static noinline'
in copy_clone_args_from_user for consistency with kernel coding style.
No functional change intended. The goal is to improve readability and
maintain consistent ordering of qualifiers across the codebase.
Signed-off-by: Dishank Jogi <dishank.jogi@siqol.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250716093525.449994-1-dishank.jogi@siqol.com
Signed-off-by: Kees Cook <kees@kernel.org>
Recently while revising RCU's cpu online checks, there was some discussion
around how IPIs synchronize with hotplug.
Add comments explaining how preemption disable creates mutual exclusion with
CPU hotplug's stop_machine mechanism. The key insight is that stop_machine()
atomically updates CPU masks and flushes IPIs with interrupts disabled, and
cannot proceed while any CPU (including the IPI sender) has preemption
disabled.
[ Apply peterz feedback. ]
Cc: Andrea Righi <arighi@nvidia.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: rcu@vger.kernel.org
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Co-developed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Fix up white space usage that does not follow the kernel coding style
rules in several places in snapshot.c.
Signed-off-by: Darshan Rathod <darshanrathod475@gmail.com>
Link: https://patch.msgid.link/20250716124216.64329-1-darshanrathod475@gmail.com
[ rjw: New subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When SCX_OPS_ENQ_MIGRATION_DISABLED is enabled, migration-disabled tasks
are also routed to ops.enqueue(). A scheduler may attempt to dispatch
such tasks directly to an idle CPU using the default idle selection
policy via scx_bpf_select_cpu_and() or scx_bpf_select_cpu_dfl().
This scenario must be properly handled by the built-in idle policy to
avoid returning an idle CPU where the target task isn't allowed to run.
Otherwise, it can lead to errors such as:
EXIT: runtime error (SCX_DSQ_LOCAL[_ON] cannot move migration disabled Chrome_ChildIOT[291646] from CPU 3 to 14)
Prevent this by explicitly handling migration-disabled tasks in the
built-in idle selection logic, maintaining their CPU affinity.
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>
The comment mentions bpf_scx_reenqueue_local(), but the function
is provided for the BPF program implementing scx, as such the
naming convention is scx_bpf_reenqueue_local(), fix the comment.
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This reverts commit cff5f49d43.
Commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") modified the cgroup_freezing() logic to verify that the FROZEN
flag is not set, affecting the return value of the freezing() function,
in order to address a warning in __thaw_task.
A race condition exists that may allow tasks to escape being frozen. The
following scenario demonstrates this issue:
CPU 0 (get_signal path) CPU 1 (freezer.state reader)
try_to_freeze read freezer.state
__refrigerator freezer_read
update_if_frozen
WRITE_ONCE(current->__state, TASK_FROZEN);
...
/* Task is now marked frozen */
/* frozen(task) == true */
/* Assuming other tasks are frozen */
freezer->state |= CGROUP_FROZEN;
/* freezing(current) returns false */
/* because cgroup is frozen (not freezing) */
break out
__set_current_state(TASK_RUNNING);
/* Bug: Task resumes running when it should remain frozen */
The existing !frozen(p) check in __thaw_task makes the
WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables
reverting the commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check
if not frozen") to resolve the issue.
The warning has been removed in the previous patch. This patch revert the
commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") to complete the fix.
Fixes: cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not frozen")
Reported-by: Zhong Jiawei<zhongjiawei1@huawei.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") modified the cgroup_freezing() logic to verify that the FROZEN
flag is not set, affecting the return value of the freezing() function,
in order to address a warning in __thaw_task.
A race condition exists that may allow tasks to escape being frozen. The
following scenario demonstrates this issue:
CPU 0 (get_signal path) CPU 1 (freezer.state reader)
try_to_freeze read freezer.state
__refrigerator freezer_read
update_if_frozen
WRITE_ONCE(current->__state, TASK_FROZEN);
...
/* Task is now marked frozen */
/* frozen(task) == true */
/* Assuming other tasks are frozen */
freezer->state |= CGROUP_FROZEN;
/* freezing(current) returns false */
/* because cgroup is frozen (not freezing) */
break out
__set_current_state(TASK_RUNNING);
/* Bug: Task resumes running when it should remain frozen */
The existing !frozen(p) check in __thaw_task makes the
WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables
reverting commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if
not frozen") to resolve the issue.
This patch removes the warning from __thaw_task. A subsequent patch will
revert commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if
not frozen") to complete the fix.
Reported-by: Zhong Jiawei<zhongjiawei1@huawei.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Before the commit 36df6e3dbd ("cgroup: make css_rstat_updated nmi
safe"), the struct llist_node is expected to be private to the one
inserting the node to the lockless list or the one removing the node
from the lockless list. After the mentioned commit, the llist_node in
the rstat code is per-cpu shared between the stacked contexts i.e.
process, softirq, hardirq & nmi. It is possible the compiler may tear
the loads or stores of llist_node. Let's avoid that.
KCSAN reported the following race:
Reported by Kernel Concurrency Sanitizer on:
CPU: 60 UID: 0 PID: 5425 ... 6.16.0-rc3-next-20250626 #1 NONE
Tainted: [E]=UNSIGNED_MODULE
Hardware name: ...
==================================================================
==================================================================
BUG: KCSAN: data-race in css_rstat_flush / css_rstat_updated
write to 0xffffe8fffe1c85f0 of 8 bytes by task 1061 on cpu 1:
css_rstat_flush+0x1b8/0xeb0
__mem_cgroup_flush_stats+0x184/0x190
flush_memcg_stats_dwork+0x22/0x50
process_one_work+0x335/0x630
worker_thread+0x5f1/0x8a0
kthread+0x197/0x340
ret_from_fork+0xd3/0x110
ret_from_fork_asm+0x11/0x20
read to 0xffffe8fffe1c85f0 of 8 bytes by task 3551 on cpu 15:
css_rstat_updated+0x81/0x180
mod_memcg_lruvec_state+0x113/0x2d0
__mod_lruvec_state+0x3d/0x50
lru_add+0x21e/0x3f0
folio_batch_move_lru+0x80/0x1b0
__folio_batch_add_and_move+0xd7/0x160
folio_add_lru_vma+0x42/0x50
do_anonymous_page+0x892/0xe90
__handle_mm_fault+0xfaa/0x1520
handle_mm_fault+0xdc/0x350
do_user_addr_fault+0x1dc/0x650
exc_page_fault+0x5c/0x110
asm_exc_page_fault+0x22/0x30
value changed: 0xffffe8fffe18e0d0 -> 0xffffe8fffe1c85f0
$ ./scripts/faddr2line vmlinux css_rstat_flush+0x1b8/0xeb0
css_rstat_flush+0x1b8/0xeb0:
init_llist_node at include/linux/llist.h:86
(inlined by) llist_del_first_init at include/linux/llist.h:308
(inlined by) css_process_update_tree at kernel/cgroup/rstat.c:148
(inlined by) css_rstat_updated_list at kernel/cgroup/rstat.c:258
(inlined by) css_rstat_flush at kernel/cgroup/rstat.c:389
$ ./scripts/faddr2line vmlinux css_rstat_updated+0x81/0x180
css_rstat_updated+0x81/0x180:
css_rstat_updated at kernel/cgroup/rstat.c:90 (discriminator 1)
These are expected race and a simple READ_ONCE/WRITE_ONCE resolves these
reports. However let's add comments to explain the race and the need for
memory barriers if stronger guarantees are needed.
More specifically the rstat updater and the flusher can race and cause a
scenario where the stats updater skips adding the css to the lockless
list but the flusher might not see those updates done by the skipped
updater. This is benign race and the subsequent flusher will flush those
stats and at the moment there aren't any rstat users which are not fine
with this kind of race. However some future user might want more
stricter guarantee, so let's add appropriate comments to ease the job of
future users.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Fixes: 36df6e3dbd ("cgroup: make css_rstat_updated nmi safe")
Signed-off-by: Tejun Heo <tj@kernel.org>
- Fix a deadlock that may occur on asynchronous device suspend
failures due to missing completion updates in error paths (Rafael
Wysocki).
- Drop a misplaced pm_restore_gfp_mask() call, which may cause
swap to be accessed too early if system suspend fails, from
suspend_devices_and_enter() (Rafael Wysocki).
- Remove duplicate filesystems_freeze/thaw() calls, which sometimes
cause systems to be unable to resume, from enter_state() (Zihuan
Zhang).
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Merge tag 'pm-6.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These address three issues introduced during the current development
cycle and related to system suspend and hibernation, one triggering
when asynchronous suspend of devices fails, one possibly affecting
memory management in the core suspend code error path, and one due to
duplicate filesystems freezing during system suspend:
- Fix a deadlock that may occur on asynchronous device suspend
failures due to missing completion updates in error paths (Rafael
Wysocki)
- Drop a misplaced pm_restore_gfp_mask() call, which may cause swap
to be accessed too early if system suspend fails, from
suspend_devices_and_enter() (Rafael Wysocki)
- Remove duplicate filesystems_freeze/thaw() calls, which sometimes
cause systems to be unable to resume, from enter_state() (Zihuan
Zhang)"
* tag 'pm-6.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: sleep: Update power.completion for all devices on errors
PM: suspend: clean up redundant filesystems_freeze/thaw() handling
PM: suspend: Drop a misplaced pm_restore_gfp_mask() call
The 'commit 35f96de041 ("bpf: Introduce BPF token object")' added
BPF token as a new kind of BPF kernel object. And BPF_OBJ_GET_INFO_BY_FD
already used to get BPF object info, so we can also get token info with
this cmd.
One usage scenario, when program runs failed with token, because of
the permission failure, we can report what BPF token is allowing with
this API for debugging.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Link: https://lore.kernel.org/r/20250716134654.1162635-1-chen.dylane@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The last iterators update (commit 515ee52b22 ("bpf: make preloaded
map iterators to display map elements count")) missed the big-endian
skeleton. Update it by running "make big" with Debian clang version
21.0.0 (++20250706105601+01c97b4953e8-1~exp1~20250706225612.1558).
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250710100907.45880-1-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Avoid invoking update_locked_rq() when the runqueue (rq) pointer is NULL
in the SCX_CALL_OP and SCX_CALL_OP_RET macros.
Previously, calling update_locked_rq(NULL) with preemption enabled could
trigger the following warning:
BUG: using __this_cpu_write() in preemptible [00000000]
This happens because __this_cpu_write() is unsafe to use in preemptible
context.
rq is NULL when an ops invoked from an unlocked context. In such cases, we
don't need to store any rq, since the value should already be NULL
(unlocked). Ensure that update_locked_rq() is only called when rq is
non-NULL, preventing calling __this_cpu_write() on preemptible context.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Fixes: 18853ba782 ("sched_ext: Track currently locked rq")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v6.15
After a recent change in clang to strengthen uninitialized warnings [1],
it points out that in one of the error paths in parse_btf_arg(), params
is used uninitialized:
kernel/trace/trace_probe.c:660:19: warning: variable 'params' is uninitialized when used here [-Wuninitialized]
660 | return PTR_ERR(params);
| ^~~~~~
Match many other NO_BTF_ENTRY error cases and return -ENOENT, clearing
up the warning.
Link: https://lore.kernel.org/all/20250715-trace_probe-fix-const-uninit-warning-v1-1-98960f91dd04@kernel.org/
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2110
Fixes: d157d76944 ("tracing/probes: Support BTF field access from $retval")
Link: 2464313eef [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Extract the complex expedited handling condition in rcu_read_unlock_special()
into a separate function rcu_unlock_needs_exp_handling() with detailed
comments explaining each condition.
This improves code readability. No functional change intended.
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Currently, SRCU-fast grace periods use synchronize_rcu() to provide the
needed ordering with readers, even given an expedited SRCU-fast grace
period, which isn't all that expedited. This commit therefore instead
uses synchronize_rcu_expedited() if there is an expedited SRCU-fast
grace period in flight.
Of course, given an non-expedited SRCU-fast grace period blocked in
synchronize_rcu(), a later request for an expedited SRCU-fast grace
period will wait for that synchronize_rcu() to return before switching
to use of synchronize_rcu_expedited(). If this turns out to be a real
problem for a production workload, we can increase the complexity (but
likely also degrade the energy efficiency) to speed things up further.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Because SRCU-lite is being replaced by SRCU-fast, this commit removes
support for SRCU-lite from rcutorture.c
Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period. There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.
[ paulmck: Apply Christoph Hellwig feedback. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Because SRCU-lite is being replaced by SRCU-fast, this commit removes
support for SRCU-lite from refscale.c.
Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period. There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.
[ paulmck: Apply Christoph Hellwig feedback. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
During rcu_read_unlock_special(), if this happens during irq_exit(), we
can lockup if an IPI is issued. This is because the IPI itself triggers
the irq_exit() path causing a recursive lock up.
This is precisely what Xiongfeng found when invoking a BPF program on
the trace_tick_stop() tracepoint As shown in the trace below. Fix by
managing the irq_work state correctly.
irq_exit()
__irq_exit_rcu()
/* in_hardirq() returns false after this */
preempt_count_sub(HARDIRQ_OFFSET)
tick_irq_exit()
tick_nohz_irq_exit()
tick_nohz_stop_sched_tick()
trace_tick_stop() /* a bpf prog is hooked on this trace point */
__bpf_trace_tick_stop()
bpf_trace_run2()
rcu_read_unlock_special()
/* will send a IPI to itself */
irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu);
A simple reproducer can also be obtained by doing the following in
tick_irq_exit(). It will hang on boot without the patch:
static inline void tick_irq_exit(void)
{
+ rcu_read_lock();
+ WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true);
+ rcu_read_unlock();
+
Reported-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Closes: https://lore.kernel.org/all/9acd5f9f-6732-7701-6880-4b51190aa070@huawei.com/
Tested-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
[neeraj: Apply Frederic's suggested fix for PREEMPT_RT]
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
On kernels built with CONFIG_IRQ_WORK=y, when rcu_read_unlock() is
invoked within an interrupts-disabled region of code [1], it will invoke
rcu_read_unlock_special(), which uses an irq-work handler to force the
system to notice when the RCU read-side critical section actually ends.
That end won't happen until interrupts are enabled at the soonest.
In some kernels, such as those booted with rcutree.use_softirq=y, the
irq-work handler is used unconditionally.
The per-CPU rcu_data structure's ->defer_qs_iw_pending field is
updated by the irq-work handler and is both read and updated by
rcu_read_unlock_special(). This resulted in the following KCSAN splat:
------------------------------------------------------------------------
BUG: KCSAN: data-race in rcu_preempt_deferred_qs_handler / rcu_read_unlock_special
read to 0xffff96b95f42d8d8 of 1 bytes by task 90 on cpu 8:
rcu_read_unlock_special+0x175/0x260
__rcu_read_unlock+0x92/0xa0
rt_spin_unlock+0x9b/0xc0
__local_bh_enable+0x10d/0x170
__local_bh_enable_ip+0xfb/0x150
rcu_do_batch+0x595/0xc40
rcu_cpu_kthread+0x4e9/0x830
smpboot_thread_fn+0x24d/0x3b0
kthread+0x3bd/0x410
ret_from_fork+0x35/0x40
ret_from_fork_asm+0x1a/0x30
write to 0xffff96b95f42d8d8 of 1 bytes by task 88 on cpu 8:
rcu_preempt_deferred_qs_handler+0x1e/0x30
irq_work_single+0xaf/0x160
run_irq_workd+0x91/0xc0
smpboot_thread_fn+0x24d/0x3b0
kthread+0x3bd/0x410
ret_from_fork+0x35/0x40
ret_from_fork_asm+0x1a/0x30
no locks held by irq_work/8/88.
irq event stamp: 200272
hardirqs last enabled at (200272): [<ffffffffb0f56121>] finish_task_switch+0x131/0x320
hardirqs last disabled at (200271): [<ffffffffb25c7859>] __schedule+0x129/0xd70
softirqs last enabled at (0): [<ffffffffb0ee093f>] copy_process+0x4df/0x1cc0
softirqs last disabled at (0): [<0000000000000000>] 0x0
------------------------------------------------------------------------
The problem is that irq-work handlers run with interrupts enabled, which
means that rcu_preempt_deferred_qs_handler() could be interrupted,
and that interrupt handler might contain an RCU read-side critical
section, which might invoke rcu_read_unlock_special(). In the strict
KCSAN mode of operation used by RCU, this constitutes a data race on
the ->defer_qs_iw_pending field.
This commit therefore disables interrupts across the portion of the
rcu_preempt_deferred_qs_handler() that updates the ->defer_qs_iw_pending
field. This suffices because this handler is not a fast path.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Add zoned block commands to blk_fill_rwbs:
- ZONE APPEND will be decoded as 'ZA'
- ZONE RESET will be decoded as 'ZR'
- ZONE RESET ALL will be decoded as 'ZRA'
- ZONE FINISH will be decoded as 'ZF'
- ZONE OPEN will be decoded as 'ZO'
- ZONE CLOSE will be decoded as 'ZC'
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250715115324.53308-2-johannes.thumshirn@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Drop the direct pm_restore_gfp_mask() call from the KEXEC_JUMP flow in
kernel_kexec() because it is redundant. Namely, dpm_resume_end()
called beforehand in the same code path invokes that function and
it is sufficient to invoke it once.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/1949230.tdWV9SEqCh@rjwysocki.net
[ rjw: Rebase after fixing up previous changes ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
If dpm_suspend_start() fails, dpm_resume_end() must be called to
recover devices whose suspend callbacks have been called, but this
does not happen in the KEXEC_JUMP flow's error path due to a confused
goto target label.
Address this by using the correct target label in the goto statement in
question and drop the Resume_console label that is not used any more.
Fixes: 2965faa5e0 ("kexec: split kexec_load syscall from kexec core code")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/2396879.ElGaqSPkdT@rjwysocki.net
[ rjw: Drop unused label and amend the changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The recently introduced support for freezing filesystems during system
suspend included calls to filesystems_freeze() in both suspend_prepare()
and enter_state(), as well as calls to filesystems_thaw() in both
suspend_finish() and the Unlock path in enter_state(). These are
redundant.
Moreover, calling filesystems_freeze() twice, from both suspend_prepare()
and enter_state(), leads to a black screen and makes the system unable
to resume in some cases.
Address this as follows:
- filesystems_freeze() is already called in suspend_prepare(), which
is the proper and consistent place to handle pre-suspend operations.
The second call in enter_state() is unnecessary and so remove it.
- filesystems_thaw() is invoked in suspend_finish(), which covers
successful suspend/resume paths. In the failure case, add a call
to filesystems_thaw() only when needed, avoiding the duplicate call
in the general Unlock path.
This change simplifies the suspend code and avoids repeated freeze/thaw
calls, while preserving correct ordering and behavior.
Fixes: eacfbf7419 ("power: freeze filesystems during suspend/resume")
Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
Link: https://patch.msgid.link/20250712030824.81474-1-zhangzihuan@kylinos.cn
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The pm_restore_gfp_mask() call added by commit 12ffc3b151 ("PM:
Restrict swap use to later in the suspend sequence") to
suspend_devices_and_enter() is done too early because it takes
place before calling dpm_resume() in dpm_resume_end() and some
swap-backing devices may not be ready at that point. Moreover,
dpm_resume_end() called subsequently in the same code path invokes
pm_restore_gfp_mask() again and calling it twice in a row is
pointless.
Drop the misplaced pm_restore_gfp_mask() call from
suspend_devices_and_enter() to address this issue.
Fixes: 12ffc3b151 ("PM: Restrict swap use to later in the suspend sequence")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/2810409.mvXUDI8C0e@rjwysocki.net
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add kerneldoc for '__get_insn_slot' function to fix W=1 warnings:
kernel/kprobes.c:141 function parameter 'c' not described in '__get_insn_slot'
Link: https://lore.kernel.org/all/20250704143817707TOCcfTRWsO5OAbQ2eYoU9@zte.com.cn/
Signed-off-by: Peng Jiang <jiang.peng9@zte.com.cn>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
lockdep_unregister_key() is called from critical code paths, including
sections where rtnl_lock() is held. For example, when replacing a qdisc
in a network device, network egress traffic is disabled while
__qdisc_destroy() is called for every network queue.
If lockdep is enabled, __qdisc_destroy() calls lockdep_unregister_key(),
which gets blocked waiting for synchronize_rcu() to complete.
For example, a simple tc command to replace a qdisc could take 13
seconds:
# time /usr/sbin/tc qdisc replace dev eth0 root handle 0x1: mq
real 0m13.195s
user 0m0.001s
sys 0m2.746s
During this time, network egress is completely frozen while waiting for
RCU synchronization.
Use synchronize_rcu_expedited() instead to minimize the impact on
critical operations like network connectivity changes.
This improves 10x the function call to tc, when replacing the qdisc for
a network card.
# time /usr/sbin/tc qdisc replace dev eth0 root handle 0x1: mq
real 0m1.789s
user 0m0.000s
sys 0m1.613s
[boqun: Fixed the comment and add more information for the temporary
workaround, and add TODO information for hazptr]
Reported-by: Erik Lundgren <elundgren@meta.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250321-lockdep-v1-1-78b732d195fb@debian.org
hung_task_{set,clear}_blocker() is already guarded by
CONFIG_DETECT_HUNG_TASK_BLOCKER in hung_task.h, So remove
the redudant check of #ifdef.
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250704015218.359754-1-ranxiaokai627@163.com
gcc warns about 'static const' variables even in headers when building
with -Wunused-const-variables enabled:
In file included from kernel/locking/lockdep_proc.c:25:
kernel/locking/lockdep_internals.h:69:28: error: 'LOCKF_USED_IN_IRQ_READ' defined but not used [-Werror=unused-const-variable=]
69 | static const unsigned long LOCKF_USED_IN_IRQ_READ =
| ^~~~~~~~~~~~~~~~~~~~~~
kernel/locking/lockdep_internals.h:63:28: error: 'LOCKF_ENABLED_IRQ_READ' defined but not used [-Werror=unused-const-variable=]
63 | static const unsigned long LOCKF_ENABLED_IRQ_READ =
| ^~~~~~~~~~~~~~~~~~~~~~
kernel/locking/lockdep_internals.h:57:28: error: 'LOCKF_USED_IN_IRQ' defined but not used [-Werror=unused-const-variable=]
57 | static const unsigned long LOCKF_USED_IN_IRQ =
| ^~~~~~~~~~~~~~~~~
kernel/locking/lockdep_internals.h:51:28: error: 'LOCKF_ENABLED_IRQ' defined but not used [-Werror=unused-const-variable=]
51 | static const unsigned long LOCKF_ENABLED_IRQ =
| ^~~~~~~~~~~~~~~~~
This one is easy to avoid by changing the generated constant definition
into an equivalent enum.
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250409122314.2848028-6-arnd@kernel.org
Returning a large structure from the lock_stats() function causes clang
to have multiple copies of it on the stack and copy between them, which
can end up exceeding the frame size warning limit:
kernel/locking/lockdep.c:300:25: error: stack frame size (1464) exceeds limit (1280) in 'lock_stats' [-Werror,-Wframe-larger-than]
300 | struct lock_class_stats lock_stats(struct lock_class *class)
Change the calling conventions to directly operate on the caller's copy,
which apparently is what gcc does already.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250610092941.2642847-1-arnd@kernel.org
Rename the existing sha1_init() to sha1_init_raw(), since it conflicts
with the upcoming library function. This will later be removed, but
this keeps the kernel building for the introduction of the library.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250712232329.818226-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Start to flesh out the real find_proxy_task() implementation,
but avoid the migration cases for now, in those cases just
deactivate the donor task and pick again.
To ensure the donor task or other blocked tasks in the chain
aren't migrated away while we're running the proxy, also tweak
the fair class logic to avoid migrating donor or mutex blocked
tasks.
[jstultz: This change was split out from the larger proxy patch]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Connor O'Brien <connoro@google.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/20250712033407.2383110-9-jstultz@google.com
Proxy execution forms atomic pairs of tasks: The waiting donor
task (scheduling context) and a proxy (execution context). The
donor task, along with the rest of the blocked chain, follows
the proxy wrt CPU placement.
They can be the same task, in which case push/pull doesn't need any
modification. When they are different, however,
FIFO1 & FIFO42:
,-> RT42
| | blocked-on
| v
blocked_donor | mutex
| | owner
| v
`-- RT1
RT1
RT42
CPU0 CPU1
^ ^
| |
overloaded !overloaded
rq prio = 42 rq prio = 0
RT1 is eligible to be pushed to CPU1, but should that happen it will
"carry" RT42 along. Clearly here neither RT1 nor RT42 must be seen as
push/pullable.
Unfortunately, only the donor task is usually dequeued from the rq,
and the proxy'ed execution context (rq->curr) remains on the rq.
This can cause RT1 to be selected for migration from logic like the
rt pushable_list.
Thus, adda a dequeue/enqueue cycle on the proxy task before __schedule
returns, which allows the sched class logic to avoid adding the now
current task to the pushable_list.
Furthermore, tasks becoming blocked on a mutex don't need an explicit
dequeue/enqueue cycle to be made (push/pull)able: they have to be running
to block on a mutex, thus they will eventually hit put_prev_task().
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Connor O'Brien <connoro@google.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/20250712033407.2383110-8-jstultz@google.com
Add a find_proxy_task() function which doesn't do much.
When we select a blocked task to run, we will just deactivate it
and pick again. The exception being if it has become unblocked
after find_proxy_task() was called.
This allows us to validate keeping blocked tasks on the runqueue
and later deactivating them is working ok, stressing the failure
cases for when a proxy isn't found.
Greatly simplified from patch by:
Peter Zijlstra (Intel) <peterz@infradead.org>
Juri Lelli <juri.lelli@redhat.com>
Valentin Schneider <valentin.schneider@arm.com>
Connor O'Brien <connoro@google.com>
[jstultz: Split out from larger proxy patch and simplified
for review and testing.]
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/20250712033407.2383110-7-jstultz@google.com
Without proxy-exec, we normally charge the "current" task for
both its vruntime as well as its sum_exec_runtime.
With proxy, however, we have two "current" contexts: the
scheduler context and the execution context. We want to charge
the execution context rq->curr (ie: proxy/lock holder) execution
time to its sum_exec_runtime (so it's clear to userland the
rq->curr task *is* running), as well as its thread group.
However the rest of the time accounting (such a vruntime and
cgroup accounting), we charge against the scheduler context
(rq->donor) task, because it is from that task that the time
is being "donated".
If the donor and curr tasks are the same, then it's the same as
without proxy.
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/20250712033407.2383110-6-jstultz@google.com
Absorb update_curr_task() into update_curr_se(), and
in the process simplify update_curr_common().
This will make the next step a bit easier.
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/20250712033407.2383110-5-jstultz@google.com
This lets us assert mutex::wait_lock is held whenever we access
p->blocked_on, as well as warn us for unexpected state changes.
[fix conflicts, call in more places]
[jstultz: tweaked commit subject, reworked a good bit]
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Connor O'Brien <connoro@google.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/20250712033407.2383110-4-jstultz@google.com
Track the blocked-on relation for mutexes, to allow following this
relation at schedule time.
task
| blocked-on
v
mutex
| owner
v
task
This all will be used for tracking blocked-task/mutex chains
with the prox-execution patch in a similar fashion to how
priority inheritance is done with rt_mutexes.
For serialization, blocked-on is only set by the task itself
(current). And both when setting or clearing (potentially by
others), is done while holding the mutex::wait_lock.
[minor changes while rebasing]
[jstultz: Fix blocked_on tracking in __mutex_lock_common in error paths]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Connor O'Brien <connoro@google.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/20250712033407.2383110-3-jstultz@google.com
Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument
sched_proxy_exec= that can be used to disable the feature at boot
time if CONFIG_SCHED_PROXY_EXEC was enabled.
Also uses this option to allow the rq->donor to be different from
rq->curr.
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/20250712033407.2383110-2-jstultz@google.com
Support for overlapping domains added in commit e3589f6c81 ("sched:
Allow for overlapping sched_domain spans") also allowed forcefully
setting SD_OVERLAP for !NUMA domains via FORCE_SD_OVERLAP sched_feat().
Since NUMA domains had to be presumed overlapping to ensure correct
behavior, "sched_domain_topology_level::flags" was introduced. NUMA
domains added the SDTL_OVERLAP flag would ensure SD_OVERLAP was always
added during build_sched_domains() for these domains, even when
FORCE_SD_OVERLAP was off.
Condition for adding the SD_OVERLAP flag at the aforementioned commit
was as follows:
if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
sd->flags |= SD_OVERLAP;
The FORCE_SD_OVERLAP debug feature was removed in commit af85596c74
("sched/topology: Remove FORCE_SD_OVERLAP") which left the NUMA domains
as the exclusive users of SDTL_OVERLAP, SD_OVERLAP, and SD_NUMA flags.
Get rid of SDTL_OVERLAP and SD_OVERLAP as they have become redundant
and instead rely on SD_NUMA to detect the only overlapping domain
currently supported. Since SDTL_OVERLAP was the only user of
"tl->flags", get rid of "sched_domain_topology_level::flags" too.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/ba4dbdf8-bc37-493d-b2e0-2efb00ea3e19@amd.com
Define a small SDTL_INIT(maskfn, flagsfn, name) macro and use it to build the
sched_domain_topology_level array. Purely a cleanup; behaviour is unchanged.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250710105715.66594-2-me@linux.beauty
A global limits change (sched_rt_handler() logic) currently leaves stale
and/or incorrect values in variables related to accounting (e.g.
extra_bw).
Properly clean up per runqueue variables before implementing the change
and rebuild scheduling domains (so that accounting is also properly
restored) after such a change is complete.
Reported-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> # nuc & rock5b
Link: https://lore.kernel.org/r/20250627115118.438797-4-juri.lelli@redhat.com
dl_clear_root_domain() doesn't take into account the fact that per-rq
extra_bw variables retain values computed before root domain changes,
resulting in broken accounting.
Fix it by resetting extra_bw to max_bw before restoring back dl-servers
contributions.
Fixes: 2ff899e351 ("sched/deadline: Rebuild root domain accounting after every update")
Reported-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> # nuc & rock5b
Link: https://lore.kernel.org/r/20250627115118.438797-3-juri.lelli@redhat.com
dl-servers are currently initialized too early at boot when CPUs are not
fully up (only boot CPU is). This results in miscalculation of per
runqueue DEADLINE variables like extra_bw (which needs a stable CPU
count).
Move initialization of dl-servers later on after SMP has been
initialized and CPUs are all online, so that CPU count is stable and
DEADLINE variables can be computed correctly.
Fixes: d741f297bc ("sched/fair: Fair server interface")
Reported-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> # nuc & rock5b
Link: https://lore.kernel.org/r/20250627115118.438797-2-juri.lelli@redhat.com
The commit e6fe3f422b ("sched: Make multiple runqueue task counters
32-bit") changed nr_uninterruptible to an unsigned int. But the
nr_uninterruptible values for each of the CPU runqueues can grow to
large numbers, sometimes exceeding INT_MAX. This is valid, if, over
time, a large number of tasks are migrated off of one CPU after going
into an uninterruptible state. Only the sum of all nr_interruptible
values across all CPUs yields the correct result, as explained in a
comment in kernel/sched/loadavg.c.
Change the type of nr_uninterruptible back to unsigned long to prevent
overflows, and thus the miscalculation of load average.
Fixes: e6fe3f422b ("sched: Make multiple runqueue task counters 32-bit")
Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250709173328.606794-1-aruna.ramakrishna@oracle.com
MIGRATE_ISOLATE is a standalone bit, so a pageblock cannot be initialized
to just MIGRATE_ISOLATE. Add init_pageblock_migratetype() to enable
initialize a pageblock with a migratetype and isolated.
Link: https://lkml.kernel.org/r/20250617021115.2331563-4-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Richard Chang <richardycc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
cpuset is only concerned when a numa node changes its memory state, as it
needs to know the current numa nodes with memory to keep an updated
mems_allowed mask. So stop using the memory notifier and use the new numa
node notifer instead.
Link: https://lkml.kernel.org/r/20250616135158.450136-9-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Setting anon_name is done via madvise_set_anon_name() and behaves a lot of
like other madvise operations. However, apparently because madvise() has
lacked the 4th argument and prctl() not, the userspace entry point has
been implemented via prctl(PR_SET_VMA, ...) and handled first by
prctl_set_vma().
Currently prctl_set_vma() lives in kernel/sys.c but setting the
vma->anon_name is mm-specific code so extract it to a new
set_anon_vma_name() function under mm. mm/madvise.c seems to be the most
straightforward place as that's where madvise_set_anon_name() lives. Stop
declaring the latter in mm.h and instead declare set_anon_vma_name().
Link: https://lkml.kernel.org/r/20250624-anon_name_cleanup-v2-2-600075462a11@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Colin Cross <ccross@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
about it
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Merge tag 'perf_urgent_for_v6.16_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Borislav Petkov:
- Prevent perf_sigtrap() from observing an exiting task and warning
about it
* tag 'perf_urgent_for_v6.16_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix WARN in perf_sigtrap()
post-6.15 issues or aren't considered necessary for -stable kernels.
14 are for MM. Three gdb-script fixes and a kallsyms build fix.
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Merge tag 'mm-hotfixes-stable-2025-07-11-16-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"19 hotfixes. A whopping 16 are cc:stable and the remainder address
post-6.15 issues or aren't considered necessary for -stable kernels.
14 are for MM. Three gdb-script fixes and a kallsyms build fix"
* tag 'mm-hotfixes-stable-2025-07-11-16-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
Revert "sched/numa: add statistics of numa balance task"
mm: fix the inaccurate memory statistics issue for users
mm/damon: fix divide by zero in damon_get_intervals_score()
samples/damon: fix damon sample mtier for start failure
samples/damon: fix damon sample wsse for start failure
samples/damon: fix damon sample prcl for start failure
kasan: remove kasan_find_vm_area() to prevent possible deadlock
scripts: gdb: vfs: support external dentry names
mm/migrate: fix do_pages_stat in compat mode
mm/damon/core: handle damon_call_control as normal under kdmond deactivation
mm/rmap: fix potential out-of-bounds page table access during batched unmap
mm/hugetlb: don't crash when allocating a folio if there are no resv
scripts/gdb: de-reference per-CPU MCE interrupts
scripts/gdb: fix interrupts.py after maple tree conversion
maple_tree: fix mt_destroy_walk() on root leaf node
mm/vmalloc: leave lazy MMU mode on PTE mapping error
scripts/gdb: fix interrupts display after MCP on x86
lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users()
kallsyms: fix build without execinfo
After commit 7d43f1ce9d ("locking/rwsem: Enable time-based spinning on
reader-owned rwsem"), OWNER_SPINNABLE contains all possible values except
OWNER_NONSPINNABLE, namely OWNER_NULL | OWNER_WRITER | OWNER_READER.
Therefore, it is better to use OWNER_NONSPINNABLE directly to determine
whether to exit optimistic spin.
And, remove useless OWNER_SPINNABLE to simplify the code.
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250610130158.4876-1-alexjlzheng@tencent.com
Cross-merge networking fixes after downstream PR (net-6.16-rc6-2).
No conflicts.
Adjacent changes:
drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
c701574c54 ("wifi: mt76: mt7925: fix invalid array index in ssid assignment during hw scan")
b3a431fe2e ("wifi: mt76: mt7925: fix off by one in mt7925_mcu_hw_scan()")
drivers/net/wireless/mediatek/mt76/mt7996/mac.c
62da647a2b ("wifi: mt76: mt7996: Add MLO support to mt7996_tx_check_aggr()")
dc66a129ad ("wifi: mt76: add a wrapper for wcid access with validation")
drivers/net/wireless/mediatek/mt76/mt7996/main.c
3dd6f67c66 ("wifi: mt76: Move RCU section in mt7996_mcu_add_rate_ctrl()")
8989d8e90f ("wifi: mt76: mt7996: Do not set wcid.sta to 1 in mt7996_mac_sta_event()")
net/mac80211/cfg.c
58fcb1b428 ("wifi: mac80211: reject VHT opmode for unsupported channel widths")
037dc18ac3 ("wifi: mac80211: add support for storing station S1G capabilities")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The description above vpanic() has the wrong function name. Fix it up.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/23a7e8add6546b155371b7e0fbb37bb1def13d6e.1752232374.git.namcao@linutronix.de
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/lkml/20250711183802.2d8c124d@canb.auug.org.au/
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Use attach_type in bpf_link, and remove it in bpf_netns_link.
And move netns_type field to the end to fill the byte hole.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20250710032038.888700-6-chen.dylane@linux.dev
Use attach_type in bpf_link to replace the location filed, and
remove location field in tcx_link.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20250710032038.888700-5-chen.dylane@linux.dev
Use attach_type in bpf_link, and remove it in bpf_cgroup_link.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20250710032038.888700-3-chen.dylane@linux.dev
Attach_type will be set when a link is created by user. It is better to
record attach_type in bpf_link generically and have it available
universally for all link types. So add the attach_type field in bpf_link
and move the sleepable field to avoid unnecessary gap padding.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20250710032038.888700-2-chen.dylane@linux.dev
Syzbot reported a kernel warning due to a range invariant violation on
the following BPF program.
0: call bpf_get_netns_cookie
1: if r0 == 0 goto <exit>
2: if r0 & Oxffffffff goto <exit>
The issue is on the path where we fall through both jumps.
That path is unreachable at runtime: after insn 1, we know r0 != 0, but
with the sign extension on the jset, we would only fallthrough insn 2
if r0 == 0. Unfortunately, is_branch_taken() isn't currently able to
figure this out, so the verifier walks all branches. The verifier then
refines the register bounds using the second condition and we end
up with inconsistent bounds on this unreachable path:
1: if r0 == 0 goto <exit>
r0: u64=[0x1, 0xffffffffffffffff] var_off=(0, 0xffffffffffffffff)
2: if r0 & 0xffffffff goto <exit>
r0 before reg_bounds_sync: u64=[0x1, 0xffffffffffffffff] var_off=(0, 0)
r0 after reg_bounds_sync: u64=[0x1, 0] var_off=(0, 0)
Improving the range refinement for JSET to cover all cases is tricky. We
also don't expect many users to rely on JSET given LLVM doesn't generate
those instructions. So instead of improving the range refinement for
JSETs, Eduard suggested we forget the ranges whenever we're narrowing
tnums after a JSET. This patch implements that approach.
Reported-by: syzbot+c711ce17dd78e5d4fdcf@syzkaller.appspotmail.com
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/9d4fd6432a095d281f815770608fdcd16028ce0b.1752171365.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a new BPF arena kfunc for reserving a range of arena virtual
addresses without backing them with pages. This prevents the range from
being populated using bpf_arena_alloc_pages().
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250709191312.29840-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Define 4 new attack vectors that are used for controlling CPU speculation
mitigations. These may be individually disabled as part of the
mitigations= command line. Attack vector controls are combined with global
options like 'auto' or 'auto,nosmt' like 'mitigations=auto,no_user_kernel'.
The global options come first in the mitigations= string.
Cross-thread mitigations can either remain enabled fully, including
potentially disabling SMT ('auto,nosmt'), remain enabled except for
disabling SMT ('auto'), or entirely disabled through the new
'no_cross_thread' attack vector option.
The default settings for these attack vectors are consistent with existing
kernel defaults, other than the automatic disabling of VM-based attack
vectors if KVM support is not present.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-3-david.kaplan@amd.com
- small fix relevant to arm64 server and custom CMA configuration
(Feng Tang)
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Merge tag 'dma-mapping-6.16-2025-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fix from Marek Szyprowski:
- small fix relevant to arm64 server and custom CMA configuration (Feng
Tang)
* tag 'dma-mapping-6.16-2025-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma-contiguous: hornor the cma address limit setup by user
The FH_FLAG_IMMUTABLE flag was meant to avoid the reference counting on
the private hash and so to avoid the performance regression on big
machines.
With the switch to per-CPU counter this is no longer needed. That flag
was never useable on any released kernel.
Remove any support for IMMUTABLE while preserve the flags argument and
enforce it to be zero.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-5-bigeasy@linutronix.de
futex_private_hash_get() is not used outside if its compilation unit.
Make it static.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-4-bigeasy@linutronix.de
The use of rcuref_t for reference counting introduces a performance bottleneck
when accessed concurrently by multiple threads during futex operations.
Replace rcuref_t with special crafted per-CPU reference counters. The
lifetime logic remains the same.
The newly allocate private hash starts in FR_PERCPU state. In this state, each
futex operation that requires the private hash uses a per-CPU counter (an
unsigned int) for incrementing or decrementing the reference count.
When the private hash is about to be replaced, the per-CPU counters are
migrated to a atomic_t counter mm_struct::futex_atomic.
The migration process:
- Waiting for one RCU grace period to ensure all users observe the
current private hash. This can be skipped if a grace period elapsed
since the private hash was assigned.
- futex_private_hash::state is set to FR_ATOMIC, forcing all users to
use mm_struct::futex_atomic for reference counting.
- After a RCU grace period, all users are guaranteed to be using the
atomic counter. The per-CPU counters can now be summed up and added to
the atomic_t counter. If the resulting count is zero, the hash can be
safely replaced. Otherwise, active users still hold a valid reference.
- Once the atomic reference count drops to zero, the next futex
operation will switch to the new private hash.
call_rcu_hurry() is used to speed up transition which otherwise might be
delay with RCU_LAZY. There is nothing wrong with using call_rcu(). The
side effects would be that on auto scaling the new hash is used later
and the SET_SLOTS prctl() will block longer.
[bigeasy: commit description + mm get/ put_async]
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>
Link: https://lore.kernel.org/r/20250710110011.384614-3-bigeasy@linutronix.de
Export irq_domain_free_irqs_top(), making it usable for drivers compiled as
modules.
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
When hibernate with data center dGPUs, huge number of VRAM data will be
moved to shmem during dev_pm_ops.prepare(). These shmem pages take a lot
of system memory so that there's no enough free memory for creating the
hibernation image. This will cause hibernation fail and abort.
After dev_pm_ops.prepare(), call shrink_all_memory() to force move shmem
pages to swap disk and reclaim the pages, so that there's enough system
memory for hibernation image and less pages needed to copy to the image.
This patch can only flush and free about half shmem pages. It will be
better to flush and free more pages, even all of shmem pages, so that
there're less pages to be copied to the hibernation image and the overall
hibernation time can be reduced.
Signed-off-by: Samuel Zhang <guoqing.zhang@amd.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20250710062313.3226149-4-guoqing.zhang@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
On some platforms, device dependencies are not properly represented by
device links, which can cause issues when asynchronous power management
is enabled. While it is possible to disable this via sysfs, doing so
at runtime can race with the first system suspend event.
This patch introduces a kernel command-line parameter, "pm_async", which
can be set to "off" to globally disable asynchronous suspend and resume
operations from early boot. It effectively provides a way to set the
initial value of the existing pm_async sysfs knob at boot time. This
offers a robust method to fall back to synchronous (sequential)
operation, which can stabilize platforms with problematic dependencies
and also serve as a useful debugging tool.
The default behavior remains unchanged (asynchronous enabled). To
disable it, boot the kernel with the "pm_async=off" parameter.
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20250709-pm-async-off-v3-1-cb69a6fc8d04@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
With commit 343f4c49f2 ("kthread: Don't allocate kthread_struct for init
and umh") and commit 753550eb0c ("fork: Explicitly set PF_KTHREAD"), umh
task no longer have struct kthread and PF_KTHREAD flag.
Update the comment to describe what the current rules are to detect
is something is a kthread.
Link: https://lkml.kernel.org/r/20250620100801.23185-1-jqqlijiazi@gmail.com
Signed-off-by: Jiazi Li <jqqlijiazi@gmail.com>
Signed-off-by: mingzhu.wang <mingzhu.wang@transsion.com>
Suggested-by Eric W . Biederman <ebiederm@xmission.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There is an unneeded OR in the ifdef functions that are used to allocate
and free kernel stacks based on direct map or vmap. Adding dynamic stack
support would complicate this logic even further.
Therefore, clean up by changing the order so OR is no longer needed.
Link: https://lkml.kernel.org/r/20250618-fork-fixes-v4-1-2e05a2e1f5fc@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/20240311164638.2015063-3-pasha.tatashin@soleen.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There's error path that could lead to inactive uprobe:
1) uprobe_register succeeds - updates instruction to int3 and
changes ref_ctr from 0 to 1
2) uprobe_unregister fails - int3 stays in place, but ref_ctr
is changed to 0 (it's not restored to 1 in the fail path)
uprobe is leaked
3) another uprobe_register comes and re-uses the leaked uprobe
and succeds - but int3 is already in place, so ref_ctr update
is skipped and it stays 0 - uprobe CAN NOT be triggered now
4) uprobe_unregister fails because ref_ctr value is unexpected
Fix this by reverting the updated ref_ctr value back to 1 in step 2),
which is the case when uprobe_unregister fails (int3 stays in place), but
we have already updated refctr.
The new scenario will go as follows:
1) uprobe_register succeeds - updates instruction to int3 and
changes ref_ctr from 0 to 1
2) uprobe_unregister fails - int3 stays in place and ref_ctr
is reverted to 1.. uprobe is leaked
3) another uprobe_register comes and re-uses the leaked uprobe
and succeds - but int3 is already in place, so ref_ctr update
is skipped and it stays 1 - uprobe CAN be triggered now
4) uprobe_unregister succeeds
Link: https://lkml.kernel.org/r/20250514101809.2010193-1-jolsa@kernel.org
Fixes: 1cc33161a8 ("uprobes: Support SDT markers having reference count (semaphore)")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The commit 482a3767e5 ("exit: reparent: call forget_original_parent()
under tasklist_lock") moved the comment from exit_notify() to
forget_original_parent(). However, the forget_original_parent() only
handles (A), while (B) is handled in kill_orphaned_pgrp(). So remove the
unrelated part.
Link: https://lkml.kernel.org/r/20250615030930.58051-1-wangfushuai@baidu.com
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: wangfushuai <wangfushuai@baidu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It really doesn't matter if the user/admin knows what the last too big
value is. Record how many times this case is triggered would be helpful.
Solve the existing issue where relay_reset() doesn't restore the value.
Store the counter in the per-cpu buffer structure instead of the global
buffer structure. It also solves the racy condition which is likely to
happen when a few of per-cpu buffers encounter the too big data case and
then access the global field last_toobig without lock protection.
Remove the printk in relay_close() since kernel module can directly call
relay_stats() as they want.
Link: https://lkml.kernel.org/r/20250612061201.34272-6-kerneljasonxing@gmail.com
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace internal subbuf_start in blktrace with the default policy in
relayfs.
Remove dropped field from struct blktrace. Correspondingly, call the
common helper in relay. By incrementing full_count to keep track of how
many times we encountered a full buffer issue, user space will know how
many events were lost.
Link: https://lkml.kernel.org/r/20250612061201.34272-5-kerneljasonxing@gmail.com
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In this version, only support getting the counter for buffer full and
implement the framework of how it works.
Users can pass certain flag to fetch what field/statistics they expect to
know. Each time it only returns one result. So do not pass multiple
flags.
Link: https://lkml.kernel.org/r/20250612061201.34272-4-kerneljasonxing@gmail.com
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When using relay mechanism, we often encounter the case where new data are
lost or old unconsumed data are overwritten because of slow reader.
Add 'full' field in per-cpu buffer structure to detect if the above case
is happening. Relay has two modes: 1) non-overwrite mode, 2) overwrite
mode. So buffer being full here respectively means: 1) relayfs doesn't
intend to accept new data and then simply drop them, or 2) relayfs is
going to start over again and overwrite old unread data with new data.
Note: this counter doesn't need any explicit lock to protect from being
modified by different threads for the better performance consideration.
Writers calling __relay_write/relay_write should consider how to use the
lock and ensure it performs under the lock protection, thus it's not
necessary to add a new small lock here.
Link: https://lkml.kernel.org/r/20250612061201.34272-3-kerneljasonxing@gmail.com
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "relayfs: misc changes", v5.
The series mostly focuses on the error counters which helps every user
debug their own kernel module.
This patch (of 5):
prev_padding represents the unused space of certain subbuffer. If the
content of a call of relay_write() exceeds the limit of the remainder of
this subbuffer, it will skip storing in the rest space and record the
start point as buf->prev_padding in relay_switch_subbuf(). Since the buf
is a per-cpu big buffer, the point of prev_padding as a global value for
the whole buffer instead of a single subbuffer (whose padding info is
stored in buf->padding[]) seems meaningless from the real use cases, so we
don't bother to record it any more.
Link: https://lkml.kernel.org/r/20250612061201.34272-1-kerneljasonxing@gmail.com
Link: https://lkml.kernel.org/r/20250612061201.34272-2-kerneljasonxing@gmail.com
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Passing the __GFP_ZERO flag to alloc_page should result in less overhead
th= an using memset()
Link: https://lkml.kernel.org/r/20250610225639.314970-3-git@elijahs.space
Signed-off-by: Elijah Wright <git@elijahs.space>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The current allocation of VMAP stack memory is using (THREADINFO_GFP &
~__GFP_ACCOUNT) which is a complicated way of saying (GFP_KERNEL |
__GFP_ZERO):
<linux/thread_info.h>:
define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO)
<linux/gfp_types.h>:
define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)
This is an unfortunate side-effect of independent changes blurring the
picture:
commit 19809c2da2 changed (THREADINFO_GFP |
__GFP_HIGHMEM) to just THREADINFO_GFP since highmem became implicit.
commit 9b6f7e163c then added stack caching
and rewrote the allocation to (THREADINFO_GFP & ~__GFP_ACCOUNT) as cached
stacks need to be accounted separately. However that code, when it
eventually accounts the memory does this:
ret = memcg_kmem_charge(vm->pages[i], GFP_KERNEL, 0)
so the memory is charged as a GFP_KERNEL allocation.
Define a unique GFP_VMAP_STACK to use
GFP_KERNEL | __GFP_ZERO and move the comment there.
Link: https://lkml.kernel.org/r/20250509-gfp-stack-v1-1-82f6f7efc210@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reported-by: Mateusz Guzik <mjguzik@gmail.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are two data types: "struct vm_struct" and "struct vm_stack" that
have the same local variable names: vm_stack, or vm, or s, which makes the
code confusing to read.
Change the code so the naming is consistent:
struct vm_struct is always called vm_area
struct vm_stack is always called vm_stack
One change altering vfree(vm_stack) to vfree(vm_area->addr) may look like
a semantic change but it is not: vm_area->addr points to the vm_stack.
This was done to improve readability.
[linus.walleij@linaro.org: rebased and added new users of the variable names, address review comments]
Link: https://lore.kernel.org/20240311164638.2015063-4-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20250509-fork-fixes-v3-2-e6c69dd356f2@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Previously dax pages were skipped by the pagewalk code as pud_special() or
vm_normal_page{_pmd}() would be false for DAX pages. Now that dax pages
are refcounted normally that is no longer the case, so the pagewalk code
will start returning them.
Most callers already explicitly filter for DAX or zone device pages so
don't need updating. However some don't, so add checks to those callers.
Link: https://lkml.kernel.org/r/4ecb7b357fc5b435588024770b88bbb695c30090.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Björn Töpel <bjorn@kernel.org>
Cc: Björn Töpel <bjorn@rivosinc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Groves <john@groves.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This reverts commit ad6b26b6a0.
This commit introduces per-memcg/task NUMA balance statistics, but
unfortunately it introduced a NULL pointer exception due to the following
race condition: After a swap task candidate was chosen, its mm_struct
pointer was set to NULL due to task exit. Later, when performing the
actual task swapping, the p->mm caused the problem.
CPU0 CPU1
:
...
task_numa_migrate
task_numa_find_cpu
task_numa_compare
# a normal task p is chosen
env->best_task = p
# p exit:
exit_signals(p);
p->flags |= PF_EXITING
exit_mm
p->mm = NULL;
migrate_swap_stop
__migrate_swap_task((arg->src_task, arg->dst_cpu)
count_memcg_event_mm(p->mm, NUMA_TASK_SWAP)# p->mm is NULL
task_lock() should be held and the PF_EXITING flag needs to be checked to
prevent this from happening. After discussion, the conclusion was that
adding a lock is not worthwhile for some statistics calculations. Revert
the change and rely on the tracepoint for this purpose.
Link: https://lkml.kernel.org/r/20250704135620.685752-1-yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/20250708064917.BBD13C4CEED@smtp.kernel.org
Fixes: ad6b26b6a0 ("sched/numa: add statistics of numa balance task")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Reported-by: Jirka Hladky <jhladky@redhat.com>
Closes: https://lore.kernel.org/all/CAE4VaGBLJxpd=NeRJXpSCuw=REhC5LWJpC29kDy-Zh2ZDyzQZA@mail.gmail.com/
Reported-by: Srikanth Aithal <Srikanth.Aithal@amd.com>
Reported-by: Suneeth D <Suneeth.D@amd.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Hladky <jhladky@redhat.com>
Cc: Libo Chen <libo.chen@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The comment above buffer mentions sign, 10 bytes width for number and null
terminator, but buffer itself isn't large enough to hold that much data.
This is a cosmetic change, since PID cannot be negative, other than -1.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Link: https://lore.kernel.org/20250617152110.2530-1-a.sadovnikov@ispras.ru
Signed-off-by: Artem Sadovnikov <a.sadovnikov@ispras.ru>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Rewind persistent ring buffer pages which have been read in the previous
boot. Those pages are highly possible to be lost before writing it to the
disk if the previous kernel crashed. In this case, the trace data is kept
on the persistent ring buffer, but it can not be read because its commit
size has been reset after read. This skips clearing the commit size of
each sub-buffer and recover it after reboot.
Note: If you read the previous boot data via trace_pipe, that is not
accessible in that time. But reboot without clearing (or reusing) the read
data, the read data is recovered again in the next boot.
Thus, when you read the previous boot data, clear it by `echo > trace`.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/174899582116.955054.773265393511190051.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Now that there are 2 monitors for real-time applications, users may want to
enable both of them simultaneously. Make the number of per-task monitor
configurable. Default it to 2 for now.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/93e83313fc4ba7f6e66f4abe80ca5f5494d658d0.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add a monitor for checking that real-time tasks do not go to sleep in a
manner that may cause undesirable latency.
Also change
RV depends on TRACING
to
RV select TRACING
to avoid the following recursive dependency:
error: recursive dependency detected!
symbol TRACING is selected by PREEMPTIRQ_TRACEPOINTS
symbol PREEMPTIRQ_TRACEPOINTS depends on TRACE_IRQFLAGS
symbol TRACE_IRQFLAGS is selected by RV_MON_SLEEP
symbol RV_MON_SLEEP depends on RV
symbol RV depends on TRACING
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/75bc5bcc741d153aa279c95faf778dff35c5c8ad.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Userspace real-time applications may have design flaws that they raise
page faults in real-time threads, and thus have unexpected latencies.
Add an linear temporal logic monitor to detect this scenario.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/78fea8a2de6d058241d3c6502c1a92910772b0ed.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add the container "rtapp" which is the monitor collection for detecting
problems with real-time applications. The monitors will be added in the
follow-up commits.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/fb18b87631d386271de00959d8d4826f23fcd1cd.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
While attempting to implement DA monitors for some complex specifications,
deterministic automaton is found to be inappropriate as the specification
language. The automaton is complicated, hard to understand, and
error-prone.
For these cases, linear temporal logic is more suitable as the
specification language.
Add support for linear temporal logic runtime verification monitor.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/d366c1fed60ed4e8f6451f3c15a99755f2740b5f.1752088709.git.namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
CONFIG_DA_MON_EVENTS is not specific to deterministic automaton. It could
be used for other monitor types. Therefore rename it to
CONFIG_RV_MON_EVENTS.
This prepares for the introduction of linear temporal logic monitor.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/507210517123d887c1d208aa2fd45ec69765d3f0.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Each RV monitor has one static buffer to send to the reactors. If multiple
errors are detected simultaneously, the one buffer could be overwritten.
Instead, leave it to the reactors to handle buffering.
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
vpanic() is useful for implementing runtime verification reactors. Add it.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
vprintk_deferred() is useful for implementing runtime verification
reactors. Make it public.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Without "#undef TRACE_INCLUDE_FILE", there could be a build error due to
TRACE_INCLUDE_FILE being redefined. Therefore add it.
Also fix a typo while at it.
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/f805e074581e927bb176c742c981fa7675b6ebe5.1752088709.git.namcao@linutronix.de
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Always trigger a resched after a protected period even if the entity is
still eligible. It can happen that an entity remains eligible at the end
of the protected period but must let an entity with a shorter slice to run
in order to keep its lag shorter than slice. This is particulalry true
with run to parity which tries to maximize the lag.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-7-vincent.guittot@linaro.org
When an entity is enqueued without preempting current, we must ensure
that the slice protection is updated to take into account the slice
duration of the newly enqueued task so that its lag will not exceed
its slice (+ tick).
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-6-vincent.guittot@linaro.org
Run to parity ensures that current will get a chance to run its full
slice in one go but this can create large latency and/or lag for
entities with shorter slice that have exhausted their previous slice
and wait to run their next slice.
Clamp the run to parity to the shortest slice of all enqueued entities.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-5-vincent.guittot@linaro.org
Even if the waking task can preempt current, it might not be the one
selected by pick_task_fair. Check that the waking task will be selected
if we cancel the slice protection before doing so.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-4-vincent.guittot@linaro.org
EEVDF expects the scheduler to allocate a time quantum to the selected
entity and then pick a new entity for next quantum.
Although this notion of time quantum is not strictly doable in our case,
we can ensure a minimum runtime for each task most of the time and pick a
new entity after a minimum time has elapsed.
Reuse the slice protection of run to parity to ensure such runtime
quantum.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-3-vincent.guittot@linaro.org
Replace the test by the relevant protect_slice() function.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dhaval Giani (AMD) <dhaval@gianis.ca>
Link: https://lkml.kernel.org/r/20250708165630.1948751-2-vincent.guittot@linaro.org
Chris reported that commit 5f6bd380c7 ("sched/rt: Remove default
bandwidth control") caused a significant dip in his favourite
benchmark of the day. Simply disabling dl_server cured things.
His workload hammers the 0->1, 1->0 transitions, and the
dl_server_{start,stop}() overhead kills it -- fairly obviously a bad
idea in hind sight and all that.
Change things around to only disable the dl_server when there has not
been a fair task around for a whole period. Since the default period
is 1 second, this ensures the benchmark never trips this, overhead
gone.
Fixes: 557a6bfc66 ("sched/fair: Add trivial fair server")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20250702121158.465086194@infradead.org
Dietmar reported that commit 3840cbe24c ("sched: psi: fix bogus
pressure spikes from aggregation race") caused a regression for him on
a high context switch rate benchmark (schbench) due to the now
repeating cpu_clock() calls.
In particular the problem is that get_recent_times() will extrapolate
the current state to 'now'. But if an update uses a timestamp from
before the start of the update, it is possible to get two reads
with inconsistent results. It is effectively back-dating an update.
(note that this all hard-relies on the clock being synchronized across
CPUs -- if this is not the case, all bets are off).
Combine this problem with the fact that there are per-group-per-cpu
seqcounts, the commit in question pushed the clock read into the group
iteration, causing tree-depth cpu_clock() calls. On architectures
where cpu_clock() has appreciable overhead, this hurts.
Instead move to a per-cpu seqcount, which allows us to have a single
clock read for all group updates, increasing internal consistency and
lowering update overhead. This comes at the cost of a longer update
side (proportional to the tree depth) which can cause the read side to
retry more often.
Fixes: 3840cbe24c ("sched: psi: fix bogus pressure spikes from aggregation race")
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>,
Link: https://lkml.kernel.org/20250522084844.GC31726@noisy.programming.kicks-ass.net
schbench (https://github.com/masoncl/schbench.git) is showing a
regression from previous production kernels that bisected down to:
sched/fair: Remove sysctl_sched_migration_cost condition (c5b0a7eefc)
The schbench command line was:
schbench -L -m 4 -M auto -t 256 -n 0 -r 0 -s 0
This creates 4 message threads pinned to CPUs 0-3, and 256x4 worker
threads spread across the rest of the CPUs. Neither the worker threads
or the message threads do any work, they just wake each other up and go
back to sleep as soon as possible.
The end result is the first 4 CPUs are pegged waking up those 1024
workers, and the rest of the CPUs are constantly banging in and out of
idle. If I take a v6.9 Linus kernel and revert that one commit,
performance goes from 3.4M RPS to 5.4M RPS.
schedstat shows there are ~100x more new idle balance operations, and
profiling shows the worker threads are spending ~20% of their CPU time
on new idle balance. schedstats also shows that almost all of these new
idle balance attemps are failing to find busy groups.
The fix used here is to crank up the cost of the newidle balance whenever it
fails. Since we don't want sd->max_newidle_lb_cost to grow out of
control, this also changes update_newidle_cost() to use
sysctl_sched_migration_cost as the upper limit on max_newidle_lb_cost.
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20250626144017.1510594-2-clm@fb.com
Since exit_task_work() runs after perf_event_exit_task_context() updated
ctx->task to TASK_TOMBSTONE, perf_sigtrap() from perf_pending_task() might
observe event->ctx->task == TASK_TOMBSTONE.
Swap the early exit tests in order not to hit WARN_ON_ONCE().
Closes: https://syzkaller.appspot.com/bug?extid=2fe61cb2a86066be6985
Reported-by: syzbot <syzbot+2fe61cb2a86066be6985@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/b1c224bd-97f9-462c-a3e3-125d5e19c983@I-love.SAKURA.ne.jp
The upcoming auxiliary clocks need this hook, too.
To separate the architecture hooks from the timekeeper internals, refactor
the hook to only operate on a single vDSO clock.
While at it, use a more robust #define for the hook override.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-3-df7d9f87b9b8@linutronix.de
The logic to configure a 'struct vdso_clock' from a
'struct tk_read_base' is copied two times.
Split it into a shared function to reduce the duplication,
especially as another user will be added for auxiliary clocks.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-2-df7d9f87b9b8@linutronix.de
A CPU mask on the stack is broken for large values of CONFIG_NR_CPUS:
kernel/trace/preemptirq_delay_test.c: In function ‘preemptirq_delay_run’:
kernel/trace/preemptirq_delay_test.c:143:1: error: the frame size of 8512 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]
Fall back to dynamic allocation here.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Song Chen <chensong_2000@189.cn>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250620111215.3365305-1-arnd@kernel.org
Fixes: 4b9091e1c1 ("kernel: trace: preemptirq_delay_test: add cpu affinity")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Freeing of filters requires to wait for both an RCU grace period as well as
a RCU task trace wait period after they have been detached from their
lists. The trace task period can be quite large so the freeing of the
filters was moved to use the call_rcu*() routines. The problem with that is
that the callback functions of call_rcu*() is done from a soft irq and can
cause latencies if the callback takes a bit of time.
The filters are freed per event in a system and the syscalls system
contains an event per system call, which can be over 700 events. Freeing 700
filters in a bottom half is undesirable.
Instead, move the freeing to use queue_rcu_work() which is done in task
context.
Link: https://lore.kernel.org/all/9a2f0cd0-1561-4206-8966-f93ccd25927f@paulmck-laptop/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250609131732.04fd303b@gandalf.local.home
Fixes: a9d0aab5eb ("tracing: Fix regression of filter waiting a long time on RCU synchronization")
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The dedicated cpumask_next_wrap() is more verbose and effective than
cpumask_next() followed by cpumask_first().
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250605000651.45281-1-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The per-CPU data section is handled differently than the other sections.
The memory allocations requires a special __percpu pointer and then the
section is copied into the view of each CPU. Therefore the SHF_ALLOC
flag is removed to ensure move_module() skips it.
Later, relocations are applied and apply_relocations() skips sections
without SHF_ALLOC because they have not been copied. This also skips the
per-CPU data section.
The missing relocations result in a NULL pointer on x86-64 and very
small values on x86-32. This results in a crash because it is not
skipped like NULL pointer would and can't be dereferenced.
Such an assignment happens during static per-CPU lock initialisation
with lockdep enabled.
Allow relocation processing for the per-CPU section even if SHF_ALLOC is
missing.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202506041623.e45e4f7d-lkp@intel.com
Fixes: 1a6100caae425 ("Don't relocate non-allocated regions in modules.") #v2.6.1-rc3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Link: https://lore.kernel.org/r/20250610163328.URcsSUC1@linutronix.de
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Message-ID: <20250610163328.URcsSUC1@linutronix.de>
All error conditions in move_module() set the return value by updating the
ret variable. Therefore, it is not necessary to the initialize the variable
when declaring it.
Remove the unnecessary initialization.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Link: https://lore.kernel.org/r/20250618122730.51324-3-petr.pavlu@suse.com
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Message-ID: <20250618122730.51324-3-petr.pavlu@suse.com>
The function move_module() uses the variable t to track how many memory
types it has allocated and consequently how many should be freed if an
error occurs.
The variable is initially set to 0 and is updated when a call to
module_memory_alloc() fails. However, move_module() can fail for other
reasons as well, in which case t remains set to 0 and no memory is freed.
Fix the problem by initializing t to MOD_MEM_NUM_TYPES. Additionally, make
the deallocation loop more robust by not relying on the mod_mem_type_t enum
having a signed integer as its underlying type.
Fixes: c7ee8aebf6 ("module: add stop-grap sanity check on module memcpy()")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Link: https://lore.kernel.org/r/20250618122730.51324-2-petr.pavlu@suse.com
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Message-ID: <20250618122730.51324-2-petr.pavlu@suse.com>
