syzbot

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BUG: KCSAN: data-race in lookup_fast / retain_dentry

write to 0xffff88800e66ca80 of 4 bytes by task 12673 on cpu 1:
 retain_dentry+0x1c3/0x240 fs/dcache.c:659
 dput+0x10e/0x420 fs/dcache.c:873
 path_put+0x1b/0x30 fs/namei.c:496
 do_utimes_path fs/utimes.c:98 [inline]
 do_utimes fs/utimes.c:143 [inline]
 do_futimesat fs/utimes.c:197 [inline]
 __do_sys_utimes fs/utimes.c:210 [inline]
 __se_sys_utimes+0x105/0x1f0 fs/utimes.c:207
 __x64_sys_utimes+0x2d/0x40 fs/utimes.c:207
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88800e66ca80 of 4 bytes by task 12675 on cpu 0:
 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]
 path_setxattr+0x4c/0x170 fs/xattr.c:562
 __do_sys_setxattr fs/xattr.c:582 [inline]
 __se_sys_setxattr fs/xattr.c:578 [inline]
 __x64_sys_setxattr+0x69/0x80 fs/xattr.c:578
 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: 12675 Comm: syz-executor.5 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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