KCSAN: data-race in __io_free_req / __io_uring_files_cancel

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3cea11cd Linux 5.10-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12bbe6fc500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=8cc17a8aa425876d8322
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+8cc17a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __io_free_req / __io_uring_files_cancel

write to 0xffff88813ac85a68 of 1 bytes by task 10874 on cpu 1:
__io_uring_files_cancel+0x5c/0x1310 fs/io_uring.c:8678
io_uring_files_cancel include/linux/io_uring.h:50 [inline]
exit_files+0x6a/0xc0 fs/file.c:456
do_exit+0x3ed/0x15a0 kernel/exit.c:801
do_group_exit+0xc8/0x170 kernel/exit.c:903
get_signal+0xf9b/0x1510 kernel/signal.c:2757
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 0xffff88813ac85a68 of 1 bytes by task 10878 on cpu 0:
__io_free_req+0x7e/0x220 fs/io_uring.c:1841
io_free_req fs/io_uring.c:2067 [inline]
io_double_put_req fs/io_uring.c:2203 [inline]
__io_req_task_cancel+0xc6/0x110 fs/io_uring.c:2004
io_async_task_func+0x42b/0x650 fs/io_uring.c:5055
task_work_run+0x8e/0x110 kernel/task_work.c:151
io_wq_manager+0x15d/0x790 fs/io-wq.c:792
kthread+0x1fa/0x220 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10878 Comm: io_wq_manager Not tainted 5.10.0-rc2-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.