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BUG: KCSAN: data-race in __d_lookup_done / __dentry_kill

write to 0xffff8881392ad780 of 4 bytes by task 27657 on cpu 1:
 __d_lookup_done+0x82/0x1d0 fs/dcache.c:2683
 __d_add+0x31e/0x490 fs/dcache.c:2703
 d_add+0x41/0x50 fs/dcache.c:2736
 simple_lookup+0x85/0x90 fs/libfs.c:75
 lookup_open fs/namei.c:3193 [inline]
 open_last_lookups fs/namei.c:3285 [inline]
 path_openat+0xb5a/0x20b0 fs/namei.c:3491
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_open fs/open.c:1211 [inline]
 __se_sys_open fs/open.c:1207 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1207
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881392ad780 of 4 bytes by task 27651 on cpu 0:
 dentry_unlist fs/dcache.c:547 [inline]
 __dentry_kill+0x1ef/0x4e0 fs/dcache.c:578
 dentry_kill fs/dcache.c:695 [inline]
 dput+0xc6/0x360 fs/dcache.c:888
 handle_mounts fs/namei.c:1474 [inline]
 step_into+0x442/0xec0 fs/namei.c:1772
 walk_component+0x190/0x350 fs/namei.c:1948
 lookup_last fs/namei.c:2397 [inline]
 path_lookupat+0x12d/0x570 fs/namei.c:2421
 filename_lookup+0xff/0x390 fs/namei.c:2454
 user_path_at_empty+0x3b/0x50 fs/namei.c:2734
 user_path_at include/linux/namei.h:60 [inline]
 inotify_find_inode fs/notify/inotify/inotify_user.c:350 [inline]
 __do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:751 [inline]
 __se_sys_inotify_add_watch+0x120/0x670 fs/notify/inotify/inotify_user.c:704
 __x64_sys_inotify_add_watch+0x3f/0x50 fs/notify/inotify/inotify_user.c:704
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27651 Comm: systemd-udevd Tainted: G        W         5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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