syzbot

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

write to 0xffff888120530cd0 of 8 bytes by task 8727 on cpu 1:
 __hlist_bl_del include/linux/list_bl.h:128 [inline]
 ___d_drop fs/dcache.c:490 [inline]
 __d_drop+0x116/0x250 fs/dcache.c:497
 __dentry_kill+0x12f/0x450 fs/dcache.c:574
 shrink_dentry_list+0x478/0x530 fs/dcache.c:1141
 shrink_dcache_parent+0x4d/0x3f0 fs/dcache.c:1568
 vfs_rmdir+0x156/0x2a0 fs/namei.c:3716
 do_rmdir+0x16e/0x300 fs/namei.c:3773
 __do_sys_rmdir fs/namei.c:3791 [inline]
 __se_sys_rmdir fs/namei.c:3789 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3789
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120530cd0 of 8 bytes by task 5085 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:338 [inline]
 __d_lookup+0x14d/0x3b0 fs/dcache.c:2396
 lookup_fast+0x67/0x370 fs/namei.c:1502
 walk_component+0x5c/0x350 fs/namei.c:1856
 lookup_last fs/namei.c:2309 [inline]
 path_lookupat+0x12d/0x560 fs/namei.c:2333
 filename_lookup+0xf2/0x380 fs/namei.c:2366
 user_path_at_empty+0x3b/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x260/0x500 fs/open.c:423
 __do_sys_access fs/open.c:482 [inline]
 __se_sys_access fs/open.c:480 [inline]
 __x64_sys_access+0x33/0x40 fs/open.c:480
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5085 Comm: systemd-udevd Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================