syzbot

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BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff888142420310 of 8 bytes by task 13653 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:335 [inline]
 __d_lookup_rcu+0x120/0x290 fs/dcache.c:2400
 lookup_fast+0x8e/0x290 fs/namei.c:1621
 walk_component+0x3f/0x230 fs/namei.c:1990
 lookup_last fs/namei.c:2451 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2475
 filename_lookup+0x126/0x300 fs/namei.c:2504
 user_path_at_empty+0x42/0x110 fs/namei.c:2877
 user_path_at include/linux/namei.h:57 [inline]
 __do_sys_chdir fs/open.c:551 [inline]
 __se_sys_chdir+0x4f/0x140 fs/open.c:545
 __x64_sys_chdir+0x1f/0x30 fs/open.c:545
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888142420310 of 8 bytes by task 2744 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xc7/0x210 fs/dcache.c:2579
 __d_add+0x367/0x490 fs/dcache.c:2794
 d_add+0x45/0x50 fs/dcache.c:2817
 simple_lookup+0x89/0xa0 fs/libfs.c:76
 __lookup_hash+0xbc/0x180 fs/namei.c:1602
 do_unlinkat+0x14c/0x4f0 fs/namei.c:4302
 __do_sys_unlink fs/namei.c:4364 [inline]
 __se_sys_unlink fs/namei.c:4362 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4362
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2744 Comm: udevd Not tainted 6.2.0-syzkaller-12998-gc0927a7a5391-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
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