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BUG: KCSAN: data-race in __dentry_kill / fast_dput

write to 0xffff888106d14f10 of 8 bytes by task 28451 on cpu 0:
 __d_drop fs/dcache.c:575 [inline]
 __dentry_kill+0x142/0x4b0 fs/dcache.c:667
 dput+0x5e/0xd0 fs/dcache.c:911
 handle_mounts fs/namei.c:1640 [inline]
 step_into+0x5b2/0x820 fs/namei.c:1976
 walk_component+0x162/0x220 fs/namei.c:2144
 link_path_walk+0x544/0x900 fs/namei.c:2503
 path_lookupat+0x63/0x2a0 fs/namei.c:2662
 do_o_path+0x45/0x130 fs/namei.c:4026
 path_openat+0x1df9/0x2170 fs/namei.c:4048
 do_filp_open+0x1f1/0x230 fs/namei.c:4084
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 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 0xffff888106d14f10 of 8 bytes by task 28450 on cpu 1:
 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
 handle_mounts fs/namei.c:1640 [inline]
 step_into+0x5b2/0x820 fs/namei.c:1976
 walk_component+0x162/0x220 fs/namei.c:2144
 link_path_walk+0x544/0x900 fs/namei.c:2503
 path_parentat fs/namei.c:2710 [inline]
 __filename_parentat+0x15c/0x3f0 fs/namei.c:2734
 filename_parentat fs/namei.c:2752 [inline]
 filename_create+0x79/0x290 fs/namei.c:4129
 do_mkdirat+0x52/0x3f0 fs/namei.c:4400
 __do_sys_mkdirat fs/namei.c:4425 [inline]
 __se_sys_mkdirat fs/namei.c:4423 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:4423
 x64_sys_call+0x2be0/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:259
 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: 0xffff888237986608 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 28450 Comm: syz.0.43093 Tainted: G        W           6.16.0-rc5-syzkaller-00224-g379f604cc3dc #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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