syzbot

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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff8881069b8550 of 8 bytes by task 3065 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
 do_unlinkat+0x257/0x4c0 fs/namei.c:4402
 __do_sys_unlink fs/namei.c:4447 [inline]
 __se_sys_unlink fs/namei.c:4445 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4445
 x64_sys_call+0x286b/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881069b8550 of 8 bytes by task 3359 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:3589 [inline]
 path_openat+0x10fc/0x1d80 fs/namei.c:3796
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff8882379c0328 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3359 Comm: udevd Not tainted 6.9.0-rc3-syzkaller-00344-g8f2c057754b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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