syzbot

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BUG: KCSAN: data-race in io_sq_thread / io_sq_thread_finish

write to 0xffff88811dd4e0f8 of 8 bytes by task 30756 on cpu 0:
 io_sq_thread+0xfb3/0x10d0 fs/io_uring.c:6912
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88811dd4e0f8 of 8 bytes by task 29592 on cpu 1:
 io_sq_thread_stop fs/io_uring.c:7251 [inline]
 io_put_sq_data fs/io_uring.c:7267 [inline]
 io_sq_thread_finish+0x26b/0x390 fs/io_uring.c:7282
 io_ring_ctx_free fs/io_uring.c:8586 [inline]
 io_ring_exit_work+0x4fe/0x1110 fs/io_uring.c:8783
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

value changed: 0xffff88815992e040 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29592 Comm: kworker/u4:9 Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound io_ring_exit_work
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