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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88813e992180 of 4 bytes by task 3230 on cpu 1:
 __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:2740
 ext4_mknod+0x210/0x300 fs/ext4/namei.c:2814
 vfs_mknod+0x2ed/0x340 fs/namei.c:3810
 do_mknodat+0x229/0x3c0
 __do_sys_mknod fs/namei.c:3894 [inline]
 __se_sys_mknod fs/namei.c:3892 [inline]
 __x64_sys_mknod+0x4f/0x60 fs/namei.c:3892
 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 0xffff88813e992180 of 4 bytes by task 3241 on cpu 0:
 d_revalidate fs/namei.c:854 [inline]
 lookup_fast+0x172/0x360 fs/namei.c:1657
 open_last_lookups fs/namei.c:3370 [inline]
 path_openat+0x477/0x1b30 fs/namei.c:3607
 do_filp_open+0x105/0x220 fs/namei.c:3637
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1254
 do_sys_open fs/open.c:1270 [inline]
 __do_sys_open fs/open.c:1278 [inline]
 __se_sys_open fs/open.c:1274 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1274
 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: 0x00080000 -> 0x00580040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3241 Comm: syz-executor.5 Not tainted 5.18.0-syzkaller-11080-g664a393a2663-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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