[moderation] [fs?] KCSAN: data-race in __ep_remove / __fput (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 22a40d14b572 Linux 6.10-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=189a9469c2e6b22e1f35
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/ebe2f3933faf/disk-22a40d14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+189a94...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ep_remove / __fput

write to 0xffff88810f2358d0 of 8 bytes by task 6036 on cpu 1:
__ep_remove+0x3c9/0x450 fs/eventpoll.c:826
ep_remove_safe fs/eventpoll.c:864 [inline]
ep_clear_and_put+0x158/0x260 fs/eventpoll.c:900
ep_eventpoll_release+0x32/0x50 fs/eventpoll.c:937
__fput+0x2c2/0x660 fs/file_table.c:422
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810f2358d0 of 8 bytes by task 6037 on cpu 0:
eventpoll_release include/linux/eventpoll.h:45 [inline]
__fput+0x234/0x660 fs/file_table.c:413
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888102f1e010 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6037 Comm: syz.0.1032 Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


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