syzbot

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BUG: KCSAN: data-race in __dentry_kill / lookup_fast

write to 0xffff88811ad02780 of 4 bytes by task 17776 on cpu 1:
 d_lru_del fs/dcache.c:504 [inline]
 __dentry_kill+0xa8/0x460 fs/dcache.c:665
 finish_dput+0x2b/0x200 fs/dcache.c:879
 dput+0x52/0x60 fs/dcache.c:928
 lookup_dcache fs/namei.c:1719 [inline]
 lookup_one_qstr_excl+0x233/0x250 fs/namei.c:1742
 __start_dirop fs/namei.c:2875 [inline]
 start_dirop fs/namei.c:2884 [inline]
 filename_create+0x155/0x220 fs/namei.c:4888
 do_mknodat+0x139/0x4f0 fs/namei.c:5035
 __do_sys_mknodat fs/namei.c:5080 [inline]
 __se_sys_mknodat fs/namei.c:5077 [inline]
 __x64_sys_mknodat+0x5e/0x70 fs/namei.c:5077
 x64_sys_call+0x2b33/0x3000 arch/x86/include/generated/asm/syscalls_64.h:260
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811ad02780 of 4 bytes by task 17787 on cpu 0:
 d_revalidate fs/namei.c:976 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1814
 lookup_fast_for_open fs/namei.c:4486 [inline]
 open_last_lookups fs/namei.c:4520 [inline]
 path_openat+0x415/0x23c0 fs/namei.c:4793
 do_filp_open+0x15d/0x280 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1447
 x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00040007 -> 0x00004007

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17787 Comm: syz.8.4568 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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