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BUG: KCSAN: data-race in dentry_kill / fast_dput

write to 0xffff8881071da790 of 8 bytes by task 8497 on cpu 0:
 __d_drop fs/dcache.c:607 [inline]
 dentry_kill+0x139/0x540 fs/dcache.c:853
 finish_dput+0x16/0x1d0 fs/dcache.c:1030
 dput+0x43/0x50 fs/dcache.c:1071
 handle_mounts fs/namei.c:1759 [inline]
 step_into_slowpath+0x38c/0x4c0 fs/namei.c:2110
 step_into fs/namei.c:2158 [inline]
 open_last_lookups fs/namei.c:4787 [inline]
 path_openat+0x706/0x11c0 fs/namei.c:5013
 do_file_open+0x16c/0x290 fs/namei.c:5045
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881071da790 of 8 bytes by task 8369 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:402 [inline]
 retain_dentry fs/dcache.c:901 [inline]
 fast_dput+0x64/0x300 fs/dcache.c:1000
 dput+0x1a/0x50 fs/dcache.c:1069
 handle_mounts fs/namei.c:1759 [inline]
 step_into_slowpath+0x38c/0x4c0 fs/namei.c:2110
 step_into fs/namei.c:2158 [inline]
 open_last_lookups fs/namei.c:4787 [inline]
 path_openat+0x706/0x11c0 fs/namei.c:5013
 do_file_open+0x16c/0x290 fs/namei.c:5045
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff8882377ef280 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8369 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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