[moderation] [perf?] KCSAN: data-race in event_sched_out / perf_mmap_rb

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7c6c4ed80b87 Merge tag 'vfs-7.0-rc8.fixes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1129b302580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a78dd265deac3a9
dashboard link: https://syzkaller.appspot.com/bug?extid=17f62843d6e3e668eea1
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ac...@kernel.org adrian...@intel.com alexander...@linux.intel.com iro...@google.com james...@linaro.org jo...@kernel.org linux-...@vger.kernel.org linux-pe...@vger.kernel.org mark.r...@arm.com mi...@redhat.com namh...@kernel.org pet...@infradead.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/952ebc34a0d7/disk-7c6c4ed8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d3c6b295fa45/vmlinux-7c6c4ed8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6cbdb6b4817a/bzImage-7c6c4ed8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17f628...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in event_sched_out / perf_mmap_rb

read to 0xffff88810e381fd0 of 8 bytes by task 21833 on cpu 0:
__perf_update_times kernel/events/core.c:749 [inline]
perf_event_update_time kernel/events/core.c:762 [inline]
perf_mmap_rb+0x71d/0x950 kernel/events/core.c:7333
perf_mmap+0x1d7/0x300 kernel/events/core.c:7460
vfs_mmap include/linux/fs.h:2070 [inline]
mmap_file mm/internal.h:167 [inline]
__mmap_new_file_vma mm/vma.c:2468 [inline]
__mmap_new_vma mm/vma.c:2532 [inline]
__mmap_region mm/vma.c:2759 [inline]
mmap_region+0x195e/0x20c0 mm/vma.c:2844
do_mmap+0x9b2/0xbd0 mm/mmap.c:559
vm_mmap_pgoff+0x183/0x2d0 mm/util.c:581
ksys_mmap_pgoff+0x267/0x310 mm/mmap.c:605
x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88810e381fd0 of 8 bytes by task 21809 on cpu 1:
__perf_update_times kernel/events/core.c:-1 [inline]
perf_event_update_time kernel/events/core.c:762 [inline]
perf_event_set_state kernel/events/core.c:781 [inline]
event_sched_out+0x4c9/0x760 kernel/events/core.c:2484
group_sched_out kernel/events/core.c:2508 [inline]
__pmu_ctx_sched_out+0x3e7/0x530 kernel/events/core.c:3555
ctx_sched_out+0x279/0x2e0 kernel/events/core.c:3646
task_ctx_sched_out+0x4d/0x70 kernel/events/core.c:2955
perf_event_context_sched_out kernel/events/core.c:3853 [inline]
__perf_event_task_sched_out+0x474/0x710 kernel/events/core.c:3953
perf_event_task_sched_out include/linux/perf_event.h:1662 [inline]
prepare_task_switch kernel/sched/core.c:5086 [inline]
context_switch kernel/sched/core.c:5243 [inline]
__schedule+0xd3b/0xd40 kernel/sched/core.c:6911
preempt_schedule_common+0x11/0x30 kernel/sched/core.c:7095
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
_raw_spin_unlock_irqrestore+0x27/0x30 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:407 [inline]
__wake_up_common_lock kernel/sched/wait.c:127 [inline]
__wake_up+0x88/0xb0 kernel/sched/wait.c:146
audit_log_end+0x1e0/0x250 kernel/audit.c:2804
audit_seccomp+0xdb/0x100 kernel/auditsc.c:2955
seccomp_log kernel/seccomp.c:1048 [inline]
__seccomp_filter+0x8ec/0x1350 kernel/seccomp.c:1344
__secure_computing+0x81/0x150 kernel/seccomp.c:1404
syscall_trace_enter include/linux/entry-common.h:112 [inline]
syscall_enter_from_user_mode_work include/linux/entry-common.h:156 [inline]
syscall_enter_from_user_mode include/linux/entry-common.h:187 [inline]
do_syscall_64+0xd3/0x370 arch/x86/entry/syscall_64.c:90
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000003d41894 -> 0x0000000003d477ec

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 21809 Comm: syz.0.5496 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
==================================================================


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