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BUG: KCSAN: data-race in __io_cqring_fill_event / io_uring_poll

write to 0xffff88815233dc00 of 4 bytes by task 19659 on cpu 0:
 io_get_cqe fs/io_uring.c:1584 [inline]
 __io_cqring_fill_event+0xfb/0x350 fs/io_uring.c:1772
 io_req_complete_post+0x4d/0x640 fs/io_uring.c:1795
 io_req_complete_failed fs/io_uring.c:1858 [inline]
 __io_queue_sqe+0x304/0x460 fs/io_uring.c:7005
 io_queue_sqe fs/io_uring.c:7016 [inline]
 io_submit_sqe+0x88b/0x3eb0 fs/io_uring.c:7192
 io_submit_sqes+0x505/0xde0 fs/io_uring.c:7298
 __do_sys_io_uring_enter fs/io_uring.c:9998 [inline]
 __se_sys_io_uring_enter+0x20d/0xb30 fs/io_uring.c:9940
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9940
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88815233dc00 of 4 bytes by task 19673 on cpu 1:
 __io_cqring_events fs/io_uring.c:1568 [inline]
 io_cqring_events fs/io_uring.c:2388 [inline]
 io_uring_poll+0xc6/0x150 fs/io_uring.c:9342
 vfs_poll include/linux/poll.h:90 [inline]
 io_poll_rewait fs/io_uring.c:5288 [inline]
 io_poll_task_func+0x131/0x650 fs/io_uring.c:5374
 tctx_task_work+0x275/0x4d0 fs/io_uring.c:2164
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_signal include/linux/tracehook.h:214 [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:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
 do_syscall_64+0x50/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000019dd -> 0x000019e7

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19673 Comm: syz-executor.1 Tainted: G        W         5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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