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BUG: KCSAN: data-race in __d_rehash / fast_dput

write to 0xffff888106d59550 of 8 bytes by task 3958 on cpu 1:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xa9/0x210 fs/dcache.c:2419
 __d_add+0x373/0x4a0 fs/dcache.c:2634
 d_splice_alias+0xd6/0x270 fs/dcache.c:3025
 proc_sys_lookup+0x386/0x440 fs/proc/proc_sysctl.c:534
 lookup_open fs/namei.c:3573 [inline]
 open_last_lookups fs/namei.c:3694 [inline]
 path_openat+0xd40/0x1fa0 fs/namei.c:3930
 do_filp_open+0xf7/0x200 fs/namei.c:3960
 do_sys_openat2+0xab/0x120 fs/open.c:1415
 do_sys_open fs/open.c:1430 [inline]
 __do_sys_openat fs/open.c:1446 [inline]
 __se_sys_openat fs/open.c:1441 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1441
 x64_sys_call+0x1025/0x2d60 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

read to 0xffff888106d59550 of 8 bytes by task 3957 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:354 [inline]
 retain_dentry fs/dcache.c:698 [inline]
 fast_dput+0xd8/0x2c0 fs/dcache.c:811
 dput+0x24/0xd0 fs/dcache.c:851
 __fput+0x3fb/0x6d0 fs/file_table.c:439
 __fput_sync+0x43/0x60 fs/file_table.c:516
 __do_sys_close fs/open.c:1565 [inline]
 __se_sys_close+0xf9/0x1a0 fs/open.c:1550
 __x64_sys_close+0x1f/0x30 fs/open.c:1550
 x64_sys_call+0x25cb/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:4
 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: 0xffff8882378ace00 -> 0xffff888100537548

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3957 Comm: syz-executor Not tainted 6.11.0-syzkaller-09959-gabf2050f51fd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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