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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff88813c0250f0 of 8 bytes by task 3457 on cpu 0:
 __d_set_inode_and_type fs/dcache.c:345 [inline]
 __d_instantiate+0x1f9/0x3b0 fs/dcache.c:2008
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:2054
 ext4_mkdir+0x5e5/0x740 fs/ext4/namei.c:3050
 vfs_mkdir+0x1ef/0x2f0 fs/namei.c:4106
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4129
 __do_sys_mkdir fs/namei.c:4149 [inline]
 __se_sys_mkdir fs/namei.c:4147 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4147
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813c0250f0 of 8 bytes by task 3459 on cpu 1:
 step_into+0x123/0x800 fs/namei.c:1844
 walk_component+0x164/0x230 fs/namei.c:2008
 lookup_last fs/namei.c:2459 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2483
 filename_lookup+0x126/0x300 fs/namei.c:2512
 user_path_at_empty+0x42/0x110 fs/namei.c:2911
 user_path_at include/linux/namei.h:57 [inline]
 do_mount fs/namespace.c:3674 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount+0x24b/0x2d0 fs/namespace.c:3863
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000000 -> 0xffff888126b5e5a8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3459 Comm: syz-executor.0 Not tainted 6.7.0-rc8-syzkaller-00024-gac865f00af29 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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