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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff888139b2b540 of 4 bytes by task 10248 on cpu 1:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:1855
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:1899
 ext4_mkdir+0x5e5/0x740 fs/ext4/namei.c:3048
 vfs_mkdir+0x1ef/0x2f0 fs/namei.c:4122
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4145
 __do_sys_mkdir fs/namei.c:4165 [inline]
 __se_sys_mkdir fs/namei.c:4163 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4163
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888139b2b540 of 4 bytes by task 10249 on cpu 0:
 __d_entry_type include/linux/dcache.h:391 [inline]
 d_is_symlink include/linux/dcache.h:421 [inline]
 step_into+0x12f/0x800 fs/namei.c:1844
 walk_component fs/namei.c:2007 [inline]
 link_path_walk+0x4d8/0x7e0 fs/namei.c:2328
 path_parentat fs/namei.c:2529 [inline]
 __filename_parentat+0x13b/0x3c0 fs/namei.c:2553
 filename_parentat fs/namei.c:2571 [inline]
 filename_create+0x77/0x2b0 fs/namei.c:3872
 do_mkdirat+0x63/0x2a0 fs/namei.c:4137
 __do_sys_mkdir fs/namei.c:4165 [inline]
 __se_sys_mkdir fs/namei.c:4163 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4163
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00080000 -> 0x00280040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10249 Comm: syz-executor.0 Not tainted 6.8.0-rc1-syzkaller-00169-gecb1b8288dc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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