BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff888137eebe40 of 4 bytes by task 19279 on cpu 1:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:2011
 d_instantiate_new+0x58/0xe0 fs/dcache.c:2055
 ext4_mkdir+0x5ff/0x760 fs/ext4/namei.c:2990
 vfs_mkdir+0x216/0x320 fs/namei.c:3975
 do_mkdirat+0x105/0x280 fs/namei.c:4001
 __do_sys_mkdirat fs/namei.c:4016 [inline]
 __se_sys_mkdirat fs/namei.c:4014 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:4014
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

read to 0xffff888137eebe40 of 4 bytes by task 19281 on cpu 0:
 d_revalidate fs/namei.c:847 [inline]
 lookup_fast+0x172/0x360 fs/namei.c:1650
 walk_component+0x6b/0x280 fs/namei.c:2010
 lookup_last fs/namei.c:2469 [inline]
 path_lookupat+0x11d/0x2b0 fs/namei.c:2493
 filename_lookup+0x130/0x310 fs/namei.c:2522
 user_path_at_empty+0x3e/0x110 fs/namei.c:2895
 user_path_at include/linux/namei.h:57 [inline]
 path_setxattr+0x88/0x390 fs/xattr.c:625
 __do_sys_lsetxattr fs/xattr.c:653 [inline]
 __se_sys_lsetxattr fs/xattr.c:649 [inline]
 __x64_sys_lsetxattr+0x66/0x80 fs/xattr.c:649
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

value changed: 0x00000000 -> 0x00280000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19281 Comm: syz-executor.4 Not tainted 5.19.0-rc2-syzkaller-00258-g354c6e071be9-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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