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4616120fca7f6d48b4c640e3975352e451e9c2ce
linux/kernel
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Shakeel Butt 4616120fca cgroup: add lockless fast-path checks to cgroup_file_notify() 
Add lockless checks before acquiring cgroup_file_kn_lock:

1. READ_ONCE(cfile->kn) NULL check to skip torn-down files.
2. READ_ONCE(cfile->notified_at) rate-limit check to skip when
   within the notification interval.  If within the interval, arm
   the deferred timer via timer_reduce() and confirm it is pending
   before returning -- if the timer fired in between, fall through
   to the lock path so the notification is not lost.

Both checks have safe error directions -- a stale read can only
cause unnecessary lock acquisition, never a missed notification.

The critical section is simplified to just taking a kernfs_get()
reference and updating notified_at.

Annotate cfile->kn and cfile->notified_at write sites with
WRITE_ONCE() to pair with the lockless readers.

Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
2026-03-11 12:16:21 -10:00
..
bpf
bpf: Improve bounds when tnum has a single possible value
2026-02-27 16:11:50 -08:00
cgroup
cgroup: add lockless fast-path checks to cgroup_file_notify()
2026-03-11 12:16:21 -10:00
configs
Remove WARN_ALL_UNSEEDED_RANDOM kernel config option
2026-02-23 11:18:48 -08:00
debug
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
2026-02-21 01:02:28 -08:00
dma
dma-mapping: avoid random addr value print out on error path
2026-02-23 08:26:54 +01:00
entry
Merge branch 'core/entry' into sched/core
2026-01-30 15:40:05 +01:00
events
perf: Fix __perf_event_overflow() vs perf_remove_from_context() race
2026-02-25 15:02:34 +01:00
futex
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
gcov
Convert more 'alloc_obj' cases to default GFP_KERNEL arguments
2026-02-21 20:03:00 -08:00
irq
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kcsan
kcsan: test: Adjust "expect" allocation type for kmalloc_obj
2026-02-26 09:54:08 -08:00
livepatch
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
liveupdate
liveupdate: luo_file: remember retrieve() status
2026-02-24 11:13:26 -08:00
locking
Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses
2026-02-22 08:26:33 -08:00
module
module: Fix kernel panic when a symbol st_shndx is out of bounds
2026-02-23 19:37:28 +00:00
power
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
printk
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
rcu
Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses
2026-02-22 08:26:33 -08:00
sched
Merge tag 'cgroup-for-7.0-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2026-03-03 14:25:18 -08:00
time
Merge tag 'sysctl-7.00-fixes-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
2026-03-04 08:21:11 -08:00
trace
tracing: Fix WARN_ON in tracing_buffers_mmap_close
2026-03-03 22:25:32 -05:00
unwind
Convert more 'alloc_obj' cases to default GFP_KERNEL arguments
2026-02-21 20:03:00 -08:00
.gitignore
kheaders: rebuild kheaders_data.tar.xz when a file is modified within a minute
2025-06-24 20:30:37 +09:00
acct.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
async.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
audit_fsnotify.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
audit_tree.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
audit_watch.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
audit.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
audit.h
audit: fix comment misindentation in audit.h
2025-10-22 19:28:06 -04:00
auditfilter.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
auditsc.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
backtracetest.c
…
bounds.c
x86/asm: Remove ANNOTATE_DATA_SPECIAL usage
2025-12-03 16:53:19 +01:00
capability.c
…
cfi.c
cfi: Move BPF CFI types and helpers to generic code
2025-07-31 18:23:53 -07:00
compat.c
…
configs.c
…
context_tracking.c
context_tracking: Remove rcu_task_trace_heavyweight_{enter,exit}()
2026-01-01 16:39:46 +08:00
cpu_pm.c
syscore: Pass context data to callbacks
2025-11-14 10:01:52 +01:00
cpu.c
Merge tag 'spdx-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
2026-02-17 09:46:03 -08:00
crash_core_test.c
crash: add KUnit tests for crash_exclude_mem_range
2025-09-13 17:32:55 -07:00
crash_core.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
crash_dump_dm_crypt.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
crash_reserve.c
crash: let architecture decide crash memory export to iomem_resource
2025-11-12 10:00:15 -08:00
cred.c
cred: remove unused set_security_override_from_ctx()
2026-01-06 20:52:57 -05:00
delayacct.c
delayacct: fix uapi timespec64 definition
2026-02-08 00:13:32 -08:00
dma.c
…
elfcorehdr.c
…
exec_domain.c
…
exit.c
kthread: consolidate kthread exit paths to prevent use-after-free
2026-02-26 10:45:49 +01:00
exit.h
…
extable.c
…
fail_function.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
fork.c
unshare: fix unshare_fs() handling
2026-02-18 14:04:51 +01:00
freezer.c
freezer: Clarify that only cgroup1 freezer uses PM freezer
2025-10-30 20:10:27 +01:00
gen_kheaders.sh
kheaders: make it possible to override TAR
2025-08-06 10:23:36 +09:00
groups.c
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
2026-02-21 01:02:28 -08:00
hung_task.c
hung_task: add hung_task_sys_info sysctl to dump sys info on task-hung
2025-11-20 14:03:43 -08:00
iomem.c
…
irq_work.c
…
jump_label.c
…
kallsyms_internal.h
kallsyms: Get rid of kallsyms relative base
2026-01-22 15:58:22 -07:00
kallsyms_selftest.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kallsyms_selftest.h
…
kallsyms.c
Merge tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
2026-02-12 12:13:01 -08:00
kcmp.c
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.kexec
liveupdate: kho: move to kernel/liveupdate
2025-11-27 14:24:33 -08:00
Kconfig.locks
…
Kconfig.preempt
sched: Further restrict the preemption modes
2026-01-08 12:43:57 +01:00
kcov.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kexec_core.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kexec_elf.c
…
kexec_file.c
kexec: derive purgatory entry from symbol
2026-01-31 16:16:07 -08:00
kexec_internal.h
kexec: enable CMA based contiguous allocation
2025-08-02 12:01:38 -07:00
kexec.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kheaders.c
…
kprobes.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
kstack_erase.c
sysctl: remove __user qualifier from stack_erasing_sysctl buffer argument
2025-11-27 15:44:53 +01:00
ksyms_common.c
…
ksysfs.c
kexec: move sysfs entries to /sys/kernel/kexec
2025-11-27 14:24:42 -08:00
kthread.c
kthread: consolidate kthread exit paths to prevent use-after-free
2026-02-26 10:45:49 +01:00
latencytop.c
…
Makefile
kcov: Enable context analysis
2026-01-05 16:43:34 +01:00
module_signature.c
…
notifier.c
…
nscommon.c
nsfs: tighten permission checks for ns iteration ioctls
2026-02-27 22:00:08 +01:00
nsproxy.c
nsproxy: fix free_nsproxy() and simplify create_new_namespaces()
2025-11-14 13:10:38 +01:00
nstree.c
nstree: tighten permission checks for listing
2026-02-27 22:00:11 +01:00
padata.c
Convert more 'alloc_obj' cases to default GFP_KERNEL arguments
2026-02-21 20:03:00 -08:00
panic.c
panic: add panic_force_cpu= parameter to redirect panic to a specific CPU
2026-02-03 08:21:26 -08:00
params.c
Convert more 'alloc_obj' cases to default GFP_KERNEL arguments
2026-02-21 20:03:00 -08:00
pid_namespace.c
pid: rely on common reference count behavior
2025-11-11 10:01:32 +01:00
pid_sysctl.h
…
pid.c
Revert "pid: make __task_pid_nr_ns(ns => NULL) safe for zombie callers"
2026-02-10 11:39:30 +01:00
profile.c
…
ptrace.c
rseq: Introduce struct rseq_data
2025-11-04 08:30:50 +01:00
range.c
…
reboot.c
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
2026-02-21 01:02:28 -08:00
regset.c
…
relay.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
resource_kunit.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
resource.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
rseq.c
rseq: slice ext: Ensure rseq feature size differs from original rseq size
2026-02-23 11:19:19 +01:00
scftorture.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
scs.c
scs: fix a wrong parameter in __scs_magic
2025-11-12 10:00:13 -08:00
seccomp.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
signal.c
compiler-context-analysis: Remove __cond_lock() function-like helper
2026-01-05 16:43:33 +01:00
smp.c
smp: Introduce a helper function to check for pending IPIs
2025-11-19 18:06:50 +01:00
smpboot.c
sched/smp: Use the SMP version of idle_thread_set_boot_cpu()
2025-06-13 08:47:20 +02:00
smpboot.h
…
softirq.c
softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT
2025-09-17 16:25:41 +02:00
stacktrace.c
…
static_call_inline.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
static_call.c
…
stop_machine.c
sched/core: Fix migrate_swap() vs. hotplug
2025-07-01 15:02:03 +02:00
sys_ni.c
rseq: Implement sys_rseq_slice_yield()
2026-01-22 11:11:17 +01:00
sys.c
Merge tag 'riscv-for-linus-7.0-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
2026-02-12 19:17:44 -08:00
sysctl-test.c
sysctl: move u8 register test to lib/test_sysctl.c
2025-04-14 14:13:41 +02:00
sysctl.c
sysctl: replace SYSCTL_INT_CONV_CUSTOM macro with functions
2026-01-06 11:27:10 +01:00
task_work.c
task_work: Fix NMI race condition
2025-10-29 10:29:54 +01:00
taskstats.c
…
torture.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
tracepoint.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
tsacct.c
tsacct: skip all kernel threads
2026-01-26 19:07:13 -08:00
ucount.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
uid16.c
…
uid16.h
…
umh.c
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
2026-02-21 01:02:28 -08:00
up.c
…
user_namespace.c
Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses
2026-02-22 08:26:33 -08:00
user-return-notifier.c
…
user.c
ns: drop custom reference count initialization for initial namespaces
2025-11-11 10:01:32 +01:00
utsname_sysctl.c
…
utsname.c
Merge tag 'namespace-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
2025-09-29 11:20:29 -07:00
vhost_task.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
vmcore_info.c
Merge tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
2026-02-12 12:13:01 -08:00
watch_queue.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
watchdog_buddy.c
watchdog: fix opencoded cpumask_next_wrap() in watchdog_next_cpu()
2025-07-31 11:28:03 -04:00
watchdog_perf.c
watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency
2026-02-08 00:13:35 -08:00
watchdog.c
watchdog/softlockup: fix sample ring index wrap in need_counting_irqs()
2026-02-08 00:13:34 -08:00
workqueue_internal.h
…
workqueue.c
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00