[moderation] [perf?] KCSAN: data-race in __perf_event_read_value / event_sched_in (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d2a43e7f89da Merge tag 'hardening-v7.0-rc6' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c0d06a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a78dd265deac3a9
dashboard link: https://syzkaller.appspot.com/bug?extid=397497e98aeecfd9bf4e
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/d8475b185c6b/disk-d2a43e7f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/738f2095b357/vmlinux-d2a43e7f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47b59b07887c/bzImage-d2a43e7f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+397497...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __perf_event_read_value / event_sched_in

write to 0xffff888120800530 of 8 bytes by task 23628 on cpu 0:
__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_in+0x2f0/0xca0 kernel/events/core.c:2822
group_sched_in kernel/events/core.c:2869 [inline]
merge_sched_in+0x252/0xbb0 kernel/events/core.c:4128
visit_groups_merge+0x9db/0xfd0 kernel/events/core.c:4059
pmu_groups_sched_in kernel/events/core.c:4164 [inline]
__pmu_ctx_sched_in kernel/events/core.c:-1 [inline]
ctx_sched_in+0x3ba/0x410 kernel/events/core.c:4243
perf_event_sched_in kernel/events/core.c:-1 [inline]
perf_event_context_sched_in kernel/events/core.c:4290 [inline]
__perf_event_task_sched_in+0x678/0xad0 kernel/events/core.c:4319
perf_event_task_sched_in include/linux/perf_event.h:1639 [inline]
finish_task_switch+0x1f8/0x280 kernel/sched/core.c:5150
context_switch kernel/sched/core.c:5301 [inline]
__schedule+0x93c/0xd40 kernel/sched/core.c:6911
__schedule_loop kernel/sched/core.c:6993 [inline]
schedule+0x5e/0xd0 kernel/sched/core.c:7008
futex_do_wait kernel/futex/waitwake.c:358 [inline]
__futex_wait+0x121/0x260 kernel/futex/waitwake.c:687
futex_wait+0x9c/0x1d0 kernel/futex/waitwake.c:715
do_futex+0x2bf/0x380 kernel/futex/syscalls.c:130
__do_sys_futex kernel/futex/syscalls.c:207 [inline]
__se_sys_futex+0x2f6/0x370 kernel/futex/syscalls.c:188
__x64_sys_futex+0x78/0x90 kernel/futex/syscalls.c:188
x64_sys_call+0x24ab/0x3020 arch/x86/include/generated/asm/syscalls_64.h:203
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

read to 0xffff888120800530 of 8 bytes by task 23676 on cpu 1:
__perf_event_read_value+0x82/0x1d0 kernel/events/core.c:6047
perf_read_one kernel/events/core.c:6204 [inline]
__perf_read kernel/events/core.c:6257 [inline]
perf_read+0x2d6/0x670 kernel/events/core.c:6274
loop_rw_iter+0x2c8/0x400 include/linux/uio.h:-1
io_iter_do_read io_uring/rw.c:837 [inline]
__io_read+0xbf6/0xc50 io_uring/rw.c:951
io_read+0x4a/0x190 io_uring/rw.c:1031
__io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1384
io_issue_sqe+0x206/0xc00 io_uring/io_uring.c:1407
io_wq_submit_work+0x5bc/0x830 io_uring/io_uring.c:1519
io_worker_handle_work+0x41e/0x950 io_uring/io-wq.c:652
io_wq_worker+0x23d/0x970 io_uring/io-wq.c:706
ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000041cab82f -> 0x0000000041cb3dfe

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23676 Comm: iou-wrk-23628 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


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