[moderation] [fs?] KCSAN: data-race in do_epoll_wait / ep_poll_callback (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7ee983c850b4 Merge tag 'drm-fixes-2025-02-08' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ba61b0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e757e3762bd630b
dashboard link: https://syzkaller.appspot.com/bug?extid=d4d7d5b209df3c207199
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/68665ce6fb2f/disk-7ee983c8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/701936f0efe1/vmlinux-7ee983c8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e64b9ef70fb0/bzImage-7ee983c8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d4d7d5...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff88814e9258e8 of 4 bytes by task 31648 on cpu 0:
ep_send_events fs/eventpoll.c:1920 [inline]
ep_poll fs/eventpoll.c:2039 [inline]
do_epoll_wait+0x88b/0x1060 fs/eventpoll.c:2484
do_epoll_pwait fs/eventpoll.c:2514 [inline]
__do_sys_epoll_pwait fs/eventpoll.c:2527 [inline]
__se_sys_epoll_pwait+0x15f/0x280 fs/eventpoll.c:2521
__x64_sys_epoll_pwait+0x78/0x90 fs/eventpoll.c:2521
x64_sys_call+0xc00/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:282
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88814e9258e8 of 4 bytes by task 31651 on cpu 1:
ep_poll_callback+0x4f0/0x600 fs/eventpoll.c:1420
__wake_up_common kernel/sched/wait.c:89 [inline]
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up+0x65/0xb0 kernel/sched/wait.c:127
do_notify_pidfd kernel/signal.c:2156 [inline]
do_notify_parent+0x1e6/0x5b0 kernel/signal.c:2187
exit_notify kernel/exit.c:758 [inline]
do_exit+0xdd7/0x17f0 kernel/exit.c:958
__do_sys_exit kernel/exit.c:1054 [inline]
__se_sys_exit kernel/exit.c:1052 [inline]
__x64_sys_exit+0x1f/0x20 kernel/exit.c:1052
x64_sys_call+0x2da1/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:61
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xe000203b -> 0xe0000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 31651 Comm: syz.1.23497 Not tainted 6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================


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[syzbot]

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