syzbot

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BUG: KCSAN: data-race in __dentry_kill / lookup_fast

read-write to 0xffff888009ba4900 of 4 bytes by task 19 on cpu 0:
 dentry_unlist fs/dcache.c:519 [inline]
 __dentry_kill+0x13f/0x450 fs/dcache.c:575
 dentry_kill fs/dcache.c:692 [inline]
 dput+0x203/0x420 fs/dcache.c:878
 handle_remove drivers/base/devtmpfs.c:340 [inline]
 handle drivers/base/devtmpfs.c:379 [inline]
 devtmpfs_work_loop+0x507/0x870 drivers/base/devtmpfs.c:392
 devtmpfsd+0x33/0x40 drivers/base/devtmpfs.c:434
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff888009ba4900 of 4 bytes by task 22961 on cpu 1:
 d_revalidate fs/namei.c:767 [inline]
 lookup_fast+0x15f/0x370 fs/namei.c:1493
 walk_component+0x5c/0x350 fs/namei.c:1857
 lookup_last fs/namei.c:2310 [inline]
 path_lookupat+0x11d/0x550 fs/namei.c:2334
 filename_lookup+0xf2/0x380 fs/namei.c:2367
 user_path_at_empty+0x3b/0x50 fs/namei.c:2647
 user_path_at include/linux/namei.h:59 [inline]
 vfs_statx+0x90/0x270 fs/stat.c:185
 vfs_fstatat fs/stat.c:207 [inline]
 vfs_lstat include/linux/fs.h:3125 [inline]
 __do_sys_newlstat fs/stat.c:362 [inline]
 __se_sys_newlstat+0x46/0x250 fs/stat.c:356
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:356
 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: 1 PID: 22961 Comm: systemd-udevd Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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