KCSAN: data-race in io_wqe_worker / mm_update_next_owner (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b6505459 Linux 5.10-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128442e9500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c949fed53798f819
dashboard link: https://syzkaller.appspot.com/bug?extid=d9e50e3e137a44331160
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d9e50e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in io_wqe_worker / mm_update_next_owner

read-write to 0xffff888137c9b024 of 4 bytes by task 11828 on cpu 0:
io_worker_exit fs/io-wq.c:234 [inline]
io_wqe_worker+0x55d/0x810 fs/io-wq.c:641
kthread+0x1fd/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff888137c9b024 of 4 bytes by task 11842 on cpu 1:
mm_update_next_owner+0x1d9/0x4e0 kernel/exit.c:387
exit_mm+0x2ff/0x370 kernel/exit.c:485
do_exit+0x3c8/0x1630 kernel/exit.c:796
do_group_exit+0xc8/0x170 kernel/exit.c:906
get_signal+0xf9b/0x1510 kernel/signal.c:2758
arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11842 Comm: syz-executor.4 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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