syzbot

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BUG: KCSAN: data-race in __d_drop / __d_lookup_rcu

read to 0xffff8881346db850 of 8 bytes by task 3387 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:342 [inline]
 __d_lookup_rcu+0x13f/0x3e0 fs/dcache.c:2322
 lookup_fast+0xc1/0x360 fs/namei.c:1580
 open_last_lookups fs/namei.c:3319 [inline]
 path_openat+0x489/0x1eb0 fs/namei.c:3556
 do_filp_open+0x105/0x220 fs/namei.c:3586
 io_openat2+0x292/0x560 fs/io_uring.c:4290
 io_issue_sqe+0x160f/0x55e0
 __io_queue_sqe+0x20/0x440 fs/io_uring.c:7018
 io_queue_sqe fs/io_uring.c:7060 [inline]
 io_submit_sqe+0x77a/0x47d3 fs/io_uring.c:7263
 io_submit_sqes+0x25d/0x670 fs/io_uring.c:7369
 __do_sys_io_uring_enter fs/io_uring.c:10072 [inline]
 __se_sys_io_uring_enter+0x212/0xb00 fs/io_uring.c:10014
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:10014
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881346db850 of 8 bytes by task 3389 on cpu 1:
 __d_drop+0x16a/0x250 fs/dcache.c:483
 __dentry_kill+0x12f/0x450 fs/dcache.c:577
 dput+0x218/0x430 fs/dcache.c:888
 handle_mounts fs/namei.c:1502 [inline]
 step_into+0x468/0xee0 fs/namei.c:1800
 open_last_lookups fs/namei.c:3373 [inline]
 path_openat+0x1059/0x1eb0 fs/namei.c:3556
 do_filp_open+0x105/0x220 fs/namei.c:3586
 io_openat2+0x292/0x560 fs/io_uring.c:4290
 io_issue_sqe+0x160f/0x55e0
 io_wq_submit_work+0x1c5/0x370 fs/io_uring.c:6836
 io_worker_handle_work+0x4ca/0xbd0 fs/io-wq.c:574
 io_wqe_worker+0x1bc/0x4f0 fs/io-wq.c:630
 ret_from_fork+0x1f/0x30

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3389 Comm: iou-wrk-3387 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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