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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff888106faa9d0 of 8 bytes by task 3547 on cpu 1:
 __d_drop fs/dcache.c:566 [inline]
 __dentry_kill+0x142/0x4b0 fs/dcache.c:658
 dput+0x5e/0xd0 fs/dcache.c:902
 lookup_one_qstr_excl fs/namei.c:-1 [inline]
 do_unlinkat+0x221/0x4c0 fs/namei.c:4631
 __do_sys_unlink fs/namei.c:4689 [inline]
 __se_sys_unlink fs/namei.c:4687 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4687
 x64_sys_call+0x22a6/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106faa9d0 of 8 bytes by task 4075 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:359 [inline]
 retain_dentry fs/dcache.c:743 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:839
 dput+0x24/0xd0 fs/dcache.c:896
 handle_mounts fs/namei.c:1640 [inline]
 step_into+0x5b2/0x820 fs/namei.c:1976
 open_last_lookups fs/namei.c:3827 [inline]
 path_openat+0x13e8/0x2170 fs/namei.c:4036
 do_filp_open+0x109/0x230 fs/namei.c:4066
 do_sys_openat2+0xa6/0x110 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1455
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888237b76040 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4075 Comm: udevd Not tainted 6.15.0-rc7-syzkaller-00175-g0f8c0258bf04 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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