KCSAN: data-race in __io_queue_sqe / tctx_task_work

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 85a90500f9a1 Merge tag 'io_uring-5.14-2021-08-07' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1150aa81300000
kernel config: https://syzkaller.appspot.com/x/.config?x=325496b7f882bca
dashboard link: https://syzkaller.appspot.com/bug?extid=b3678f9d0336c9e95e96
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
CC: [asml.s...@gmail.com ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org]

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+b3678f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __io_queue_sqe / tctx_task_work

write to 0xffff8881304b82e8 of 4 bytes by task 31078 on cpu 1:
__io_queue_sqe+0x1f9/0x360 fs/io_uring.c:6476
io_req_task_submit+0x88/0x150 fs/io_uring.c:2044
tctx_task_work+0x1b8/0x460 fs/io_uring.c:1958
task_work_run+0xae/0x130 kernel/task_work.c:164
tracehook_notify_signal include/linux/tracehook.h:212 [inline]
handle_signal_work kernel/entry/common.c:146 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0xf8/0x190 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881304b82e8 of 4 bytes by task 31066 on cpu 0:
ctx_flush_and_put fs/io_uring.c:1926 [inline]
tctx_task_work+0x361/0x460 fs/io_uring.c:1976
task_work_run+0xae/0x130 kernel/task_work.c:164
tracehook_notify_signal include/linux/tracehook.h:212 [inline]
handle_signal_work kernel/entry/common.c:146 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0xf8/0x190 kernel/entry/common.c:209
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31066 Comm: syz-executor.3 Not tainted 5.14.0-rc4-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.