syzbot

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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff8881069f7b50 of 8 bytes by task 21943 on cpu 1:
 __d_drop fs/dcache.c:509 [inline]
 __dentry_kill+0x13b/0x4b0 fs/dcache.c:601
 dput+0x5c/0xd0 fs/dcache.c:845
 handle_mounts fs/namei.c:1553 [inline]
 step_into+0x21a/0x810 fs/namei.c:1842
 open_last_lookups fs/namei.c:3597 [inline]
 path_openat+0x1118/0x1da0 fs/namei.c:3804
 do_filp_open+0xf7/0x200 fs/namei.c:3834
 io_openat2+0x280/0x3a0 io_uring/openclose.c:140
 io_openat+0x1a/0x30 io_uring/openclose.c:177
 io_issue_sqe+0x181/0xc80 io_uring/io_uring.c:1751
 io_wq_submit_work+0x442/0x5c0 io_uring/io_uring.c:1860
 io_worker_handle_work+0x45a/0x9a0 io_uring/io-wq.c:597
 io_wq_worker+0x286/0x820 io_uring/io-wq.c:651
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881069f7b50 of 8 bytes by task 21942 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:347 [inline]
 retain_dentry fs/dcache.c:686 [inline]
 fast_dput+0x62/0x2b0 fs/dcache.c:782
 dput+0x24/0xd0 fs/dcache.c:839
 handle_mounts fs/namei.c:1553 [inline]
 step_into+0x21a/0x810 fs/namei.c:1842
 open_last_lookups fs/namei.c:3597 [inline]
 path_openat+0x1118/0x1da0 fs/namei.c:3804
 do_filp_open+0xf7/0x200 fs/namei.c:3834
 io_openat2+0x280/0x3a0 io_uring/openclose.c:140
 io_openat+0x1a/0x30 io_uring/openclose.c:177
 io_issue_sqe+0x181/0xc80 io_uring/io_uring.c:1751
 io_wq_submit_work+0x442/0x5c0 io_uring/io_uring.c:1860
 io_worker_handle_work+0x45a/0x9a0 io_uring/io-wq.c:597
 io_wq_worker+0x286/0x820 io_uring/io-wq.c:651
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0xffff88823742b7c0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21942 Comm: iou-wrk-21941 Tainted: G        W          6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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