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Subject[syzbot] KCSAN: data-race in __io_uring_cancel / io_uring_try_cancel_requests
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Hello,

syzbot found the following issue on:

HEAD commit: a050a6d2 Merge tag 'perf-tools-fixes-for-v5.13-2021-05-24'..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13205087d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=3bcc8a6b51ef8094
dashboard link: https://syzkaller.appspot.com/bug?extid=73554e2258b7b8bf0bbf
compiler: Debian clang version 11.0.1-2

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+73554e2258b7b8bf0bbf@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __io_uring_cancel / io_uring_try_cancel_requests

write to 0xffff88811d8df330 of 8 bytes by task 3709 on cpu 1:
io_uring_clean_tctx fs/io_uring.c:9042 [inline]
__io_uring_cancel+0x261/0x3b0 fs/io_uring.c:9136
io_uring_files_cancel include/linux/io_uring.h:16 [inline]
do_exit+0x185/0x1560 kernel/exit.c:781
do_group_exit+0xce/0x1a0 kernel/exit.c:923
get_signal+0xfc3/0x1610 kernel/signal.c:2835
arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:789
handle_signal_work kernel/entry/common.c:147 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88811d8df330 of 8 bytes by task 6412 on cpu 0:
io_uring_try_cancel_iowq fs/io_uring.c:8911 [inline]
io_uring_try_cancel_requests+0x1ce/0x8e0 fs/io_uring.c:8933
io_ring_exit_work+0x7c/0x1110 fs/io_uring.c:8736
process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
worker_thread+0x636/0xae0 kernel/workqueue.c:2422
kthread+0x1d0/0x1f0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6412 Comm: kworker/u4:9 Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound io_ring_exit_work
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
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