syzbot

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BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff8881442ec9d0 of 8 bytes by task 32542 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:361 [inline]
 __d_lookup_rcu+0x109/0x2a0 fs/dcache.c:2309
 lookup_fast+0xa3/0x320 fs/namei.c:1742
 lookup_fast_for_open fs/namei.c:3745 [inline]
 open_last_lookups fs/namei.c:3778 [inline]
 path_openat+0x43c/0x2170 fs/namei.c:4043
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1461
 x64_sys_call+0x2e9c/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881442ec9d0 of 8 bytes by task 32543 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0x9e/0x1f0 fs/dcache.c:2489
 d_rehash+0x26/0x40 fs/dcache.c:2503
 shmem_whiteout mm/shmem.c:4087 [inline]
 shmem_rename2+0x1e4/0x290 mm/shmem.c:4117
 vfs_rename+0x7f3/0xa40 fs/namei.c:5129
 do_renameat2+0x557/0xa10 fs/namei.c:5278
 __do_sys_renameat2 fs/namei.c:5312 [inline]
 __se_sys_renameat2 fs/namei.c:5309 [inline]
 __x64_sys_renameat2+0x7e/0x90 fs/namei.c:5309
 x64_sys_call+0x3f9/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:317
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 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: 32543 Comm: syz.6.6055 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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