syzbot

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BUG: KCSAN: data-race in __d_drop / fast_dput

write to 0xffff888107aca190 of 8 bytes by task 2981 on cpu 0:
 __d_drop+0x14d/0x240 fs/dcache.c:585
 __dentry_kill+0x125/0x4d0 fs/dcache.c:716
 finish_dput+0x2b/0x200 fs/dcache.c:927
 dput+0x52/0x60 fs/dcache.c:976
 lookup_one_qstr_excl+0x156/0x240 fs/namei.c:-1
 __start_dirop fs/namei.c:2916 [inline]
 start_dirop fs/namei.c:2938 [inline]
 filename_unlinkat+0x149/0x410 fs/namei.c:5549
 __do_sys_unlink fs/namei.c:5603 [inline]
 __se_sys_unlink+0x2b/0xe0 fs/namei.c:5600
 __x64_sys_unlink+0x1f/0x30 fs/namei.c:5600
 x64_sys_call+0x2eb6/0x3020 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107aca190 of 8 bytes by task 15492 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:379 [inline]
 retain_dentry fs/dcache.c:801 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:897
 dput+0x24/0x60 fs/dcache.c:972
 end_dirop fs/namei.c:2952 [inline]
 filename_unlinkat+0x217/0x410 fs/namei.c:5571
 __do_sys_unlink fs/namei.c:5603 [inline]
 __se_sys_unlink+0x2b/0xe0 fs/namei.c:5600
 __x64_sys_unlink+0x1f/0x30 fs/namei.c:5600
 x64_sys_call+0x2eb6/0x3020 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff8882377c2440 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15492 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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