syzbot

==================================================================
BUG: KCSAN: data-race in __d_lookup / __d_rehash

write to 0xffff888103668250 of 8 bytes by task 11676 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xb9/0x1f0 fs/dcache.c:2545
 __d_add+0x355/0x470 fs/dcache.c:2739
 d_splice_alias+0xd5/0x310 fs/dcache.c:3126
 proc_pid_instantiate+0xe9/0x100 fs/proc/base.c:3365
 proc_pid_lookup+0x123/0x1c0 fs/proc/base.c:3396
 proc_root_lookup+0x1b/0x40 fs/proc/root.c:322
 __lookup_slow+0x182/0x250 fs/namei.c:1707
 lookup_slow+0x3c/0x60 fs/namei.c:1724
 walk_component+0x23d/0x280 fs/namei.c:2020
 link_path_walk+0x459/0x7a0
 path_openat+0x199/0x1b30 fs/namei.c:3605
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1213
 do_sys_open fs/open.c:1229 [inline]
 __do_sys_openat fs/open.c:1245 [inline]
 __se_sys_openat fs/open.c:1240 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1240
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888103668250 of 8 bytes by task 1442 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:332 [inline]
 __d_lookup+0x12a/0x3d0 fs/dcache.c:2457
 lookup_fast+0x67/0x360 fs/namei.c:1665
 walk_component+0x6b/0x280 fs/namei.c:2016
 link_path_walk+0x459/0x7a0
 path_openat+0x199/0x1b30 fs/namei.c:3605
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1213
 do_sys_open fs/open.c:1229 [inline]
 __do_sys_openat fs/open.c:1245 [inline]
 __se_sys_openat fs/open.c:1240 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1240
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888237a625d0 -> 0xffff88811ff44488

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1442 Comm: udevd Not tainted 5.18.0-rc4-syzkaller-00291-g8013d1d3d2e3-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================