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BUG: KCSAN: data-race in __d_lookup / __d_rehash

write to 0xffff888105ea5490 of 8 bytes by task 3298 on cpu 1:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:91 [inline]
 __d_rehash+0xa4/0x1d0 fs/dcache.c:2811
 __d_add+0x131/0x1a0 fs/dcache.c:3120
 d_splice_alias_ops+0xe3/0x3b0 fs/dcache.c:3469
 proc_sys_lookup+0x1ed/0x310 fs/proc/proc_sysctl.c:544
 lookup_open+0x6aa/0x1050 fs/namei.c:4536
 open_last_lookups fs/namei.c:4774 [inline]
 path_openat+0x492/0x11c0 fs/namei.c:5013
 do_file_open+0x16c/0x290 fs/namei.c:5045
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105ea5490 of 8 bytes by task 3297 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:402 [inline]
 __d_lookup+0xf8/0x340 fs/dcache.c:2722
 lookup_fast+0x5e/0x320 fs/namei.c:1884
 lookup_fast_for_open fs/namei.c:4727 [inline]
 open_last_lookups fs/namei.c:4757 [inline]
 path_openat+0x363/0x11c0 fs/namei.c:5013
 do_file_open+0x16c/0x290 fs/namei.c:5045
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff8882379e1bb8 -> 0xffff8881073b5788

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3297 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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