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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff8881308a9540 of 4 bytes by task 24103 on cpu 0:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:2011
 d_instantiate_new+0x58/0xe0 fs/dcache.c:2055
 ext4_add_nondir+0x15e/0x180 fs/ext4/namei.c:2741
 ext4_create+0x217/0x300 fs/ext4/namei.c:2781
 vfs_create+0x1bc/0x2b0 fs/namei.c:3075
 do_mknodat+0x24f/0x3c0 fs/namei.c:3904
 __do_sys_mknodat fs/namei.c:3932 [inline]
 __se_sys_mknodat fs/namei.c:3929 [inline]
 __x64_sys_mknodat+0x5e/0x70 fs/namei.c:3929
 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+0x63/0xcd

read to 0xffff8881308a9540 of 4 bytes by task 24104 on cpu 1:
 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]
 do_fchmodat fs/open.c:643 [inline]
 __do_sys_fchmodat fs/open.c:658 [inline]
 __se_sys_fchmodat fs/open.c:655 [inline]
 __x64_sys_fchmodat+0x83/0x110 fs/open.c:655
 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+0x63/0xcd

value changed: 0x00000000 -> 0x00480000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24104 Comm: syz-executor.0 Not tainted 5.19.0-rc8-syzkaller-00155-g6a010258447d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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