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BUG: KCSAN: data-race in __d_lookup / __d_rehash

write to 0xffff88810556bcd0 of 8 bytes by task 4190 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xc4/0x220 fs/dcache.c:2403
 __d_add+0x36d/0x4a0 fs/dcache.c:2618
 d_splice_alias+0xd6/0x270 fs/dcache.c:3009
 ext4_lookup+0x18e/0x390 fs/ext4/namei.c:1882
 lookup_one_qstr_excl+0xc7/0x1a0 fs/namei.c:1607
 filename_create+0x14d/0x2b0 fs/namei.c:3901
 do_symlinkat+0x84/0x350 fs/namei.c:4508
 __do_sys_symlinkat fs/namei.c:4531 [inline]
 __se_sys_symlinkat fs/namei.c:4528 [inline]
 __x64_sys_symlinkat+0x62/0x70 fs/namei.c:4528
 x64_sys_call+0x1e00/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810556bcd0 of 8 bytes by task 3743 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:347 [inline]
 __d_lookup+0x10e/0x390 fs/dcache.c:2315
 lookup_fast+0x4c/0x2a0 fs/namei.c:1650
 open_last_lookups fs/namei.c:3542 [inline]
 path_openat+0x44c/0x1da0 fs/namei.c:3804
 do_filp_open+0xf7/0x200 fs/namei.c:3834
 do_sys_openat2+0xab/0x120 fs/open.c:1405
 do_sys_open fs/open.c:1420 [inline]
 __do_sys_openat fs/open.c:1436 [inline]
 __se_sys_openat fs/open.c:1431 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1431
 x64_sys_call+0x1057/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888237b48a90 -> 0xffff88810621fd88

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3743 Comm: udevd Not tainted 6.10.0-rc4-syzkaller-00033-g14d7c92f8df9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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