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BUG: KCSAN: data-race in __io_cqring_fill_event / io_uring_poll

write to 0xffff88814a38ac00 of 4 bytes by task 20007 on cpu 1:
 io_get_cqe fs/io_uring.c:1580 [inline]
 __io_cqring_fill_event+0xfb/0x350 fs/io_uring.c:1764
 io_submit_flush_completions+0xd1/0x450 fs/io_uring.c:2328
 __io_queue_sqe+0x290/0x420 fs/io_uring.c:6970
 io_queue_sqe fs/io_uring.c:7008 [inline]
 io_submit_sqe+0x88b/0x3eb0 fs/io_uring.c:7184
 io_submit_sqes+0x505/0xde0 fs/io_uring.c:7290
 __do_sys_io_uring_enter fs/io_uring.c:9992 [inline]
 __se_sys_io_uring_enter+0x20d/0xb30 fs/io_uring.c:9934
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9934
 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 0xffff88814a38ac00 of 4 bytes by task 19997 on cpu 0:
 __io_cqring_events fs/io_uring.c:1564 [inline]
 io_cqring_events fs/io_uring.c:2380 [inline]
 io_uring_poll+0xc6/0x150 fs/io_uring.c:9334
 vfs_poll include/linux/poll.h:90 [inline]
 do_pollfd fs/select.c:869 [inline]
 do_poll fs/select.c:917 [inline]
 do_sys_poll+0x4b8/0xad0 fs/select.c:1011
 __do_sys_poll fs/select.c:1076 [inline]
 __se_sys_poll+0xf5/0x210 fs/select.c:1064
 __x64_sys_poll+0x3f/0x50 fs/select.c:1064
 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

value changed: 0x00000060 -> 0x00000080

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19997 Comm: syz-executor.2 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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