syzbot

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BUG: KCSAN: data-race in __d_lookup / shrink_dentry_list

read-write to 0xffff88811af743c0 of 4 bytes by task 17691 on cpu 1:
 d_shrink_del fs/dcache.c:516 [inline]
 shrink_dentry_list+0x22d/0x3c0 fs/dcache.c:1166
 shrink_dcache_sb+0x15d/0x290 fs/dcache.c:1295
 reconfigure_super+0x142/0x590 fs/super.c:1058
 do_remount fs/namespace.c:3391 [inline]
 path_mount+0xaf7/0xbc0 fs/namespace.c:4151
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffff88811af743c0 of 4 bytes by task 16537 on cpu 0:
 d_same_name fs/dcache.c:2220 [inline]
 __d_lookup+0x118/0x340 fs/dcache.c:2458
 lookup_fast+0x5e/0x320 fs/namei.c:1874
 walk_component fs/namei.c:2275 [inline]
 link_path_walk+0x51c/0xe30 fs/namei.c:2647
 path_parentat fs/namei.c:2851 [inline]
 __filename_parentat+0x1a4/0x450 fs/namei.c:2875
 filename_parentat fs/namei.c:2893 [inline]
 filename_unlinkat+0x99/0x410 fs/namei.c:5509
 __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

value changed: 0x00140444 -> 0x00100044

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16537 Comm: syz-executor 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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