[moderation] [pm?] KCSAN: data-race in __ep_eventpoll_poll / wakeup_source_report_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a79a588fc176 Merge tag 'pm-6.16-rc5' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1398f3d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=eea96b85b0259840
dashboard link: https://syzkaller.appspot.com/bug?extid=f1c34e6db0a3f2b2b1d9
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [da...@kernel.org gre...@linuxfoundation.org len....@intel.com linux-...@vger.kernel.org linu...@vger.kernel.org pa...@kernel.org raf...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f0ea4205da34/disk-a79a588f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b62b224950c/vmlinux-a79a588f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9341eddbbcb3/bzImage-a79a588f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f1c34e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ep_eventpoll_poll / wakeup_source_report_event

write to 0xffff88811a31bbf8 of 1 bytes by task 5049 on cpu 0:
wakeup_source_activate drivers/base/power/wakeup.c:565 [inline]
wakeup_source_report_event+0xd6/0x280 drivers/base/power/wakeup.c:590
__pm_stay_awake+0x34/0x70 drivers/base/power/wakeup.c:611
ep_pm_stay_awake_rcu fs/eventpoll.c:727 [inline]
ep_poll_callback+0x1f6/0x550 fs/eventpoll.c:1243
__wake_up_common kernel/sched/wait.c:89 [inline]
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up+0x66/0xb0 kernel/sched/wait.c:127
unix_dgram_peer_wake_relay+0xd3/0xf0 net/unix/af_unix.c:514
__wake_up_common kernel/sched/wait.c:89 [inline]
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up_sync_key+0x52/0x80 kernel/sched/wait.c:173
__unix_dgram_recvmsg+0x3b2/0x840 net/unix/af_unix.c:2541
unix_dgram_recvmsg+0x81/0x90 net/unix/af_unix.c:2616
sock_recvmsg_nosec+0x107/0x130 net/socket.c:1017
____sys_recvmsg+0x26f/0x280 net/socket.c:2784
___sys_recvmsg+0x11f/0x370 net/socket.c:2828
do_recvmmsg+0x1ef/0x540 net/socket.c:2923
__sys_recvmmsg net/socket.c:2997 [inline]
__do_sys_recvmmsg net/socket.c:3020 [inline]
__se_sys_recvmmsg net/socket.c:3013 [inline]
__x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3013
x64_sys_call+0x1c6a/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:300
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a31bbf8 of 1 bytes by task 5050 on cpu 1:
__ep_eventpoll_poll+0x1de/0x4e0 fs/eventpoll.c:958
ep_item_poll fs/eventpoll.c:1025 [inline]
ep_send_events fs/eventpoll.c:1740 [inline]
ep_try_send_events+0x225/0x8b0 fs/eventpoll.c:1844
ep_poll fs/eventpoll.c:1907 [inline]
do_epoll_wait+0x2ac/0x690 fs/eventpoll.c:2342
__do_sys_epoll_wait fs/eventpoll.c:2350 [inline]
__se_sys_epoll_wait fs/eventpoll.c:2345 [inline]
__x64_sys_epoll_wait+0x147/0x180 fs/eventpoll.c:2345
x64_sys_call+0x26d9/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:233
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5050 Comm: syz.4.620 Not tainted 6.16.0-rc4-syzkaller-00308-ga79a588fc176 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.