syzbot

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BUG: KCSAN: data-race in dont_mount / path_lookupat

read-write to 0xffff8881083ba480 of 4 bytes by task 22854 on cpu 0:
 dont_mount+0x2a/0x40 include/linux/dcache.h:382
 vfs_unlink+0x206/0x490 fs/namei.c:5472
 filename_unlinkat+0x1e2/0x410 fs/namei.c:5540
 __do_sys_unlink fs/namei.c:5575 [inline]
 __se_sys_unlink+0x2b/0xe0 fs/namei.c:5572
 __x64_sys_unlink+0x1f/0x30 fs/namei.c:5572
 x64_sys_call+0x2eb6/0x3020 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881083ba480 of 4 bytes by task 2999 on cpu 1:
 d_managed include/linux/dcache.h:403 [inline]
 step_into fs/namei.c:2136 [inline]
 walk_component fs/namei.c:2285 [inline]
 lookup_last fs/namei.c:2780 [inline]
 path_lookupat+0x1d8/0x500 fs/namei.c:2804
 filename_lookup+0x190/0x390 fs/namei.c:2833
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x2b51/0x3020 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00300080 -> 0x00004080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2999 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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