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BUG: KCSAN: data-race in __io_cqring_fill_event / io_req_defer

write to 0xffff88802ad84a00 of 4 bytes by task 15448 on cpu 0:
 io_get_cqring fs/io_uring.c:1715 [inline]
 __io_cqring_fill_event+0x13b/0x440 fs/io_uring.c:1855
 io_cqring_add_event fs/io_uring.c:1894 [inline]
 __io_req_complete+0xd8/0x1b0 fs/io_uring.c:1938
 io_issue_sqe+0x3541/0x4220 fs/io_uring.c:1216
 io_wq_submit_work+0x25c/0x4a0 fs/io_uring.c:6402
 io_worker_handle_work+0xcc1/0x1010 fs/io-wq.c:565
 io_wqe_worker+0x221/0x880 fs/io-wq.c:607
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88802ad84a00 of 4 bytes by task 15452 on cpu 1:
 req_need_defer fs/io_uring.c:1352 [inline]
 io_req_defer+0x519/0x6e0 fs/io_uring.c:6145
 io_queue_sqe+0x24/0x420 fs/io_uring.c:6619
 io_submit_sqe+0x33e/0x620 fs/io_uring.c:6713
 io_submit_sqes+0xa8c/0x12a0 fs/io_uring.c:6961
 __do_sys_io_uring_enter fs/io_uring.c:9363 [inline]
 __se_sys_io_uring_enter+0x21f/0xb70 fs/io_uring.c:9306
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9306
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15452 Comm: syz-executor.0 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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