[moderation] [fs?] KCSAN: data-race in ep_modify / ep_poll_callback

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1c892cdd8fe0 Merge tag 'vfs-6.8-rc6.fixes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14ff8cf8180000
kernel config: https://syzkaller.appspot.com/x/.config?x=7507056e4ee79a
dashboard link: https://syzkaller.appspot.com/bug?extid=ade382e8c9ce63076932
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/139c3c1075e8/disk-1c892cdd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/84baf552e6fb/vmlinux-1c892cdd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bec5bd9af52d/bzImage-1c892cdd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ade382...@syzkaller.appspotmail.com

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

write to 0xffff88813f3ea9e8 of 4 bytes by task 18112 on cpu 0:
ep_modify+0x51/0x3f0 fs/eventpoll.c:1618
do_epoll_ctl+0x4ea/0x950 fs/eventpoll.c:2238
__do_sys_epoll_ctl fs/eventpoll.c:2275 [inline]
__se_sys_epoll_ctl fs/eventpoll.c:2266 [inline]
__x64_sys_epoll_ctl+0xc6/0xf0 fs/eventpoll.c:2266
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813f3ea9e8 of 4 bytes by task 18094 on cpu 1:
ep_poll_callback+0x4b5/0x5a0 fs/eventpoll.c:1245
__wake_up_common kernel/sched/wait.c:89 [inline]
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up+0x64/0xa0 kernel/sched/wait.c:127
sock_def_wakeup+0x5d/0x80 net/core/sock.c:3317
unix_shutdown+0x106/0x370 net/unix/af_unix.c:2941
__sys_shutdown_sock net/socket.c:2425 [inline]
__sys_shutdown net/socket.c:2437 [inline]
__do_sys_shutdown net/socket.c:2445 [inline]
__se_sys_shutdown+0xfe/0x140 net/socket.c:2443
__x64_sys_shutdown+0x31/0x40 net/socket.c:2443
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000018 -> 0xc0000019

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18094 Comm: syz-executor.4 Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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