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BUG: KCSAN: data-race in __io_cqring_fill_event / io_req_defer

write to 0xffff88812d70c480 of 4 bytes by task 19469 on cpu 1:
 io_get_cqring fs/io_uring.c:1368 [inline]
 __io_cqring_fill_event+0xfd/0x350 fs/io_uring.c:1550
 io_req_complete_post+0x58/0x540 fs/io_uring.c:1574
 __io_req_complete fs/io_uring.c:1629 [inline]
 __io_complete_rw+0x3ba/0x480 fs/io_uring.c:2479
 io_complete_rw+0x1b/0x20 fs/io_uring.c:2486
 io_rw_done fs/io_uring.c:2720 [inline]
 kiocb_done+0x1b1/0x420 fs/io_uring.c:2744
 io_read fs/io_uring.c:3325 [inline]
 io_issue_sqe+0x399d/0x6620 fs/io_uring.c:6106
 io_wq_submit_work+0x113/0x270 fs/io_uring.c:6243
 io_worker_handle_work+0x8cb/0xaf0 fs/io-wq.c:496
 io_wqe_worker+0x1c5/0x550 fs/io-wq.c:545
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88812d70c480 of 4 bytes by task 19468 on cpu 0:
 req_need_defer fs/io_uring.c:1197 [inline]
 io_req_defer+0x358/0x4a0 fs/io_uring.c:5993
 io_queue_sqe fs/io_uring.c:6441 [inline]
 io_submit_sqe+0x157d/0x33d0 fs/io_uring.c:6620
 io_submit_sqes+0x5bd/0xbd0 fs/io_uring.c:6728
 __do_sys_io_uring_enter fs/io_uring.c:9294 [inline]
 __se_sys_io_uring_enter+0x1e1/0xa80 fs/io_uring.c:9236
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9236
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19468 Comm: syz-executor.5 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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