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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff88811fb8f930 of 8 bytes by task 14136 on cpu 1:
 __d_set_inode_and_type fs/dcache.c:344 [inline]
 __d_instantiate+0x1f9/0x3c0 fs/dcache.c:1853
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:1899
 ext4_mkdir+0x5e6/0x740 fs/ext4/namei.c:3047
 vfs_mkdir+0x1f4/0x320 fs/namei.c:4131
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4154
 __do_sys_mkdir fs/namei.c:4174 [inline]
 __se_sys_mkdir fs/namei.c:4172 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4172
 x64_sys_call+0x10d4/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:84
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811fb8f930 of 8 bytes by task 14137 on cpu 0:
 step_into+0x123/0x810 fs/namei.c:1846
 walk_component+0x169/0x230 fs/namei.c:2010
 lookup_last fs/namei.c:2469 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2493
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 user_path_at include/linux/namei.h:58 [inline]
 do_mount fs/namespace.c:3689 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x24b/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 x64_sys_call+0x25c9/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881064cb7e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14137 Comm: syz.2.3886 Not tainted 6.10.0-rc5-syzkaller-00035-gafcd48134c58 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================
loop2: detected capacity change from 0 to 2048
EXT4-fs warning (device loop2): ext4_multi_mount_protect:398: Unable to create kmmpd thread for loop2.