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BUG: KCSAN: data-race in dont_mount / lookup_fast

read-write to 0xffff88811b5d0900 of 4 bytes by task 3760 on cpu 0:
 dont_mount+0x2a/0x40 include/linux/dcache.h:382
 vfs_rename+0xa05/0xad0 fs/namei.c:5939
 do_renameat2+0x383/0x810 fs/namei.c:6047
 __do_sys_rename fs/namei.c:6090 [inline]
 __se_sys_rename fs/namei.c:6088 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6088
 x64_sys_call+0x24e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b5d0900 of 4 bytes by task 4316 on cpu 1:
 d_revalidate fs/namei.c:968 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1806
 walk_component fs/namei.c:2217 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x15c/0x500 fs/namei.c:2746
 filename_lookup+0x147/0x340 fs/namei.c:2775
 user_path_at+0x3e/0x130 fs/namei.c:3567
 do_utimes_path fs/utimes.c:96 [inline]
 do_utimes+0xd9/0x210 fs/utimes.c:141
 __do_sys_utimensat fs/utimes.c:160 [inline]
 __se_sys_utimensat fs/utimes.c:144 [inline]
 __x64_sys_utimensat+0xc4/0x170 fs/utimes.c:144
 x64_sys_call+0x278c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:281
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00300080 -> 0x00000180

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4316 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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