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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff888100542f10 of 8 bytes by task 17258 on cpu 0:
 __d_drop fs/dcache.c:566 [inline]
 __dentry_kill+0x13e/0x4c0 fs/dcache.c:658
 dput+0x5c/0xd0 fs/dcache.c:902
 handle_mounts fs/namei.c:1640 [inline]
 step_into+0x226/0x860 fs/namei.c:1966
 walk_component+0x178/0x240 fs/namei.c:2134
 link_path_walk+0x4df/0x840 fs/namei.c:2490
 path_lookupat+0x6c/0x2a0 fs/namei.c:2649
 do_o_path+0x49/0x130 fs/namei.c:3975
 path_openat+0x1cc8/0x2000 fs/namei.c:3997
 do_filp_open+0x1ff/0x240 fs/namei.c:4033
 do_sys_openat2+0xaa/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+0xf8/0x120 fs/open.c:1455
 x64_sys_call+0x1ac/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100542f10 of 8 bytes by task 17257 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:365 [inline]
 retain_dentry fs/dcache.c:743 [inline]
 fast_dput+0x65/0x2c0 fs/dcache.c:839
 dput+0x24/0xd0 fs/dcache.c:896
 handle_mounts fs/namei.c:1640 [inline]
 step_into+0x226/0x860 fs/namei.c:1966
 walk_component+0x178/0x240 fs/namei.c:2134
 link_path_walk+0x4df/0x840 fs/namei.c:2490
 path_parentat+0x28/0xa0 fs/namei.c:2697
 __filename_parentat+0x3b4/0x410 fs/namei.c:2723
 filename_parentat fs/namei.c:2739 [inline]
 filename_create+0x7a/0x240 fs/namei.c:4078
 do_mkdirat+0x66/0x2e0 fs/namei.c:4349
 __do_sys_mkdirat fs/namei.c:4374 [inline]
 __se_sys_mkdirat fs/namei.c:4372 [inline]
 __x64_sys_mkdirat+0x4e/0x60 fs/namei.c:4372
 x64_sys_call+0x2ce3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888237860500 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 17257 Comm: syz.4.5198 Not tainted 6.14.0-syzkaller-09584-g7d06015d936c #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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