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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88813a2d5b40 of 4 bytes by task 12010 on cpu 0:
 __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:2989
 vfs_mkdir+0x216/0x320 fs/namei.c:3982
 do_mkdirat+0x105/0x280 fs/namei.c:4008
 __do_sys_mkdir fs/namei.c:4028 [inline]
 __se_sys_mkdir fs/namei.c:4026 [inline]
 __x64_sys_mkdir+0x40/0x50 fs/namei.c:4026
 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 0xffff88813a2d5b40 of 4 bytes by task 12011 on cpu 1:
 d_revalidate fs/namei.c:854 [inline]
 lookup_fast+0x172/0x360 fs/namei.c:1657
 walk_component+0x6b/0x280 fs/namei.c:2017
 link_path_walk+0x459/0x7a0
 path_openat+0x199/0x1b30 fs/namei.c:3656
 do_filp_open+0x105/0x220 fs/namei.c:3687
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1278
 do_sys_open fs/open.c:1294 [inline]
 __do_sys_creat fs/open.c:1370 [inline]
 __se_sys_creat fs/open.c:1364 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1364
 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: 1 PID: 12011 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-12234-g50fd82b3a9a9-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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