KCSAN: data-race in exit_mmap / io_ring_ctx_wait_and_kill

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4d02da97 Merge tag 'net-5.10-rc5' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16cbb4a9500000
kernel config: https://syzkaller.appspot.com/x/.config?x=73fc125ff8990ab9
dashboard link: https://syzkaller.appspot.com/bug?extid=1fd77129a2bae3f6c10b
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+1fd771...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in exit_mmap / io_ring_ctx_wait_and_kill

read-write to 0xffff88803e46b348 of 8 bytes by task 23445 on cpu 0:
io_unaccount_mem fs/io_uring.c:7863 [inline]
io_ring_ctx_wait_and_kill+0x2c3/0x370 fs/io_uring.c:8375
io_uring_release+0x3e/0x50 fs/io_uring.c:8393
__fput+0x243/0x4d0 fs/file_table.c:281
____fput+0x11/0x20 fs/file_table.c:314
task_work_run+0x8e/0x110 kernel/task_work.c:151
exit_task_work include/linux/task_work.h:30 [inline]
do_exit+0x437/0x15a0 kernel/exit.c:809
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

read to 0xffff88803e46b348 of 8 bytes by task 23442 on cpu 1:
exit_mmap+0x94/0x3b0 mm/mmap.c:3202
__mmput+0xa2/0x220 kernel/fork.c:1079
mmput+0x38/0x40 kernel/fork.c:1100
exit_mm+0x307/0x370 kernel/exit.c:486
do_exit+0x3c2/0x15a0 kernel/exit.c:796
do_group_exit+0x16f/0x170 kernel/exit.c:906
__do_sys_exit_group+0xb/0x10 kernel/exit.c:917
__se_sys_exit_group+0x5/0x10 kernel/exit.c:915
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23442 Comm: syz-executor.1 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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