syzbot

==================================================================
BUG: KCSAN: data-race in __dentry_kill / fast_dput

 __d_drop fs/dcache.c:521 [inline]
 __dentry_kill+0x13e/0x4c0 fs/dcache.c:613
 dput+0x5c/0xd0 fs/dcache.c:857
 __do_sys_unlink fs/namei.c:4581 [inline]
 __se_sys_unlink fs/namei.c:4579 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4579
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83

read to 0xffff888105776b50 of 8 bytes by task 23090 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+0x65/0x2c0 fs/dcache.c:794
 handle_mounts fs/namei.c:1579 [inline]
 step_into+0x21a/0x810 fs/namei.c:1891
 do_filp_open+0xf7/0x200 fs/namei.c:3960
 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
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83