syzbot

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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff888106b890d0 of 8 bytes by task 2995 on cpu 1:
 __d_drop fs/dcache.c:575 [inline]
 __dentry_kill+0x142/0x4b0 fs/dcache.c:667
 dput+0x5e/0xd0 fs/dcache.c:911
 path_put fs/namei.c:626 [inline]
 terminate_walk+0x103/0x2a0 fs/namei.c:752
 path_lookupat+0x1fc/0x2a0 fs/namei.c:2680
 filename_lookup+0x147/0x340 fs/namei.c:2692
 do_readlinkat+0x7d/0x320 fs/stat.c:576
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:610
 x64_sys_call+0x2cf3/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106b890d0 of 8 bytes by task 3519 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:752 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:848
 dput+0x24/0xd0 fs/dcache.c:905
 do_unlinkat+0x299/0x4c0 fs/namei.c:4662
 __do_sys_unlink fs/namei.c:4705 [inline]
 __se_sys_unlink fs/namei.c:4703 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4703
 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+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88823778b5a0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3519 Comm: udevd Not tainted 6.16.0-rc4-syzkaller-00049-gb4911fb0b060 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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udevd[3519]: inotify_add_watch(7, /dev/loop4p4, 10) failed: No such file or directory