syzbot

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BUG: KCSAN: data-race in __dentry_kill / retain_dentry

write to 0xffff888025108cc0 of 4 bytes by task 32580 on cpu 0:
 d_lru_add fs/dcache.c:400 [inline]
 retain_dentry+0x199/0x260 fs/dcache.c:658
 dput+0x11e/0x430 fs/dcache.c:881
 path_put+0x1b/0x30 fs/namei.c:546
 vfs_statx+0x1fd/0x290 fs/stat.c:205
 vfs_fstatat fs/stat.c:217 [inline]
 vfs_stat include/linux/fs.h:3236 [inline]
 __do_sys_newstat fs/stat.c:359 [inline]
 __se_sys_newstat+0x46/0x250 fs/stat.c:355
 __x64_sys_newstat+0x2d/0x40 fs/stat.c:355
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888025108cc0 of 4 bytes by task 4837 on cpu 1:
 dentry_unlist fs/dcache.c:545 [inline]
 __dentry_kill+0x1ef/0x450 fs/dcache.c:576
 dentry_kill fs/dcache.c:693 [inline]
 dput+0x218/0x430 fs/dcache.c:886
 handle_mounts fs/namei.c:1475 [inline]
 step_into+0x442/0xec0 fs/namei.c:1773
 walk_component+0x190/0x350 fs/namei.c:1949
 lookup_last fs/namei.c:2398 [inline]
 path_lookupat+0x12d/0x570 fs/namei.c:2422
 filename_lookup+0xff/0x390 fs/namei.c:2455
 user_path_at_empty+0x3b/0x50 fs/namei.c:2735
 user_path_at include/linux/namei.h:60 [inline]
 do_faccessat+0x260/0x510 fs/open.c:425
 __do_sys_access fs/open.c:484 [inline]
 __se_sys_access fs/open.c:482 [inline]
 __x64_sys_access+0x33/0x40 fs/open.c:482
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4837 Comm: systemd-udevd Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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