syzbot

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BUG: KCSAN: data-race in lookup_fast / shrink_dentry_list

read-write to 0xffff8881078e2540 of 4 bytes by task 4328 on cpu 1:
 d_shrink_del fs/dcache.c:527 [inline]
 shrink_dentry_list+0x108/0x1d0 fs/dcache.c:1286
 shrink_dcache_sb+0x161/0x290 fs/dcache.c:1413
 reconfigure_super+0x472/0x590 fs/super.c:998
 do_remount fs/namespace.c:3407 [inline]
 path_mount+0xaba/0xb90 fs/namespace.c:4153
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4367
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4367
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881078e2540 of 4 bytes by task 3289 on cpu 0:
 d_revalidate fs/namei.c:1034 [inline]
 lookup_fast+0x72/0x320 fs/namei.c:1881
 lookup_fast_for_open fs/namei.c:4545 [inline]
 open_last_lookups fs/namei.c:4579 [inline]
 path_openat+0x423/0x2000 fs/namei.c:4860
 do_file_open+0x16c/0x290 fs/namei.c:4892
 do_sys_openat2+0xa0/0x130 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1385
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00340444 -> 0x00300044

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3289 Comm: udevd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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