syzbot

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BUG: KCSAN: data-race in __d_rehash / fast_dput

write to 0xffff8881006566d0 of 8 bytes by task 3110 on cpu 1:
 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
 proc_sys_lookup+0x386/0x440 fs/proc/proc_sysctl.c:536
 lookup_open fs/namei.c:3483 [inline]
 open_last_lookups fs/namei.c:3574 [inline]
 path_openat+0xc85/0x1da0 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

read to 0xffff8881006566d0 of 8 bytes by task 3109 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:347 [inline]
 retain_dentry fs/dcache.c:686 [inline]
 fast_dput+0xcf/0x2b0 fs/dcache.c:799
 dput+0x24/0xd0 fs/dcache.c:839
 __fput+0x448/0x660 fs/file_table.c:430
 __fput_sync+0x44/0x60 fs/file_table.c:507
 __do_sys_close fs/open.c:1555 [inline]
 __se_sys_close+0x101/0x1b0 fs/open.c:1540
 __x64_sys_close+0x1f/0x30 fs/open.c:1540
 x64_sys_call+0x25f1/0x2d70 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: 0xffff888237532488 -> 0xffff888107c48a88

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3109 Comm: syz-executor.4 Not tainted 6.10.0-rc1-syzkaller-00104-gd8ec19857b09 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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