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BUG: KCSAN: data-race in __io_cqring_fill_event / io_uring_poll

write to 0xffff888107c2b400 of 4 bytes by task 23893 on cpu 1:
 io_get_cqe fs/io_uring.c:1424 [inline]
 __io_cqring_fill_event+0xfb/0x350 fs/io_uring.c:1606
 io_cqring_fill_event+0x28/0x30 fs/io_uring.c:1620
 io_async_cancel fs/io_uring.c:5861 [inline]
 io_issue_sqe+0x5437/0x64b0 fs/io_uring.c:6226
 __io_queue_sqe+0xe7/0x360 fs/io_uring.c:6470
 io_queue_sqe fs/io_uring.c:6513 [inline]
 io_submit_sqe+0x1695/0x3400 fs/io_uring.c:6668
 io_submit_sqes+0x822/0xe50 fs/io_uring.c:6784
 __do_sys_io_uring_enter fs/io_uring.c:9392 [inline]
 __se_sys_io_uring_enter+0x213/0xae0 fs/io_uring.c:9334
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9334
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888107c2b400 of 4 bytes by task 23903 on cpu 0:
 __io_cqring_events fs/io_uring.c:1408 [inline]
 io_cqring_events fs/io_uring.c:2197 [inline]
 io_uring_poll+0xc6/0x150 fs/io_uring.c:8746
 vfs_poll include/linux/poll.h:90 [inline]
 io_poll_rewait fs/io_uring.c:4886 [inline]
 io_poll_task_func+0x112/0x440 fs/io_uring.c:4963
 tctx_task_work+0x1b8/0x460 fs/io_uring.c:1962
 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: 0x00001f85 -> 0x00001f88

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23903 Comm: syz-executor.4 Tainted: G        W         5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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