syzbot

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BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff88810051b550 of 8 bytes by task 3006 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:366 [inline]
 __d_lookup_rcu+0x21c/0x2d0 fs/dcache.c:2358
 lookup_fast+0xa3/0x320 fs/namei.c:1792
 walk_component fs/namei.c:2217 [inline]
 link_path_walk+0x51c/0xe30 fs/namei.c:2589
 path_lookupat+0x8c/0x500 fs/namei.c:2745
 filename_lookup+0x147/0x340 fs/namei.c:2775
 vfs_statx+0x9d/0x390 fs/stat.c:353
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:536
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
 x64_sys_call+0x111f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88810051b550 of 8 bytes by task 10110 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0x9e/0x1f0 fs/dcache.c:2534
 __d_add+0x344/0x4a0 fs/dcache.c:2759
 d_add+0x47/0x50 fs/dcache.c:2782
 simple_lookup+0xba/0xd0 fs/libfs.c:81
 lookup_one_qstr_excl+0xcb/0x250 fs/namei.c:1747
 __start_dirop fs/namei.c:2866 [inline]
 start_dirop fs/namei.c:2875 [inline]
 filename_create+0x141/0x210 fs/namei.c:4879
 do_symlinkat+0x94/0x470 fs/namei.c:5534
 __do_sys_symlinkat fs/namei.c:5562 [inline]
 __se_sys_symlinkat fs/namei.c:5559 [inline]
 __x64_sys_symlinkat+0x5a/0x70 fs/namei.c:5559
 x64_sys_call+0x2a36/0x3000 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10110 Comm: syz-executor 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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