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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff8881066ac4b0 of 8 bytes by task 5172 on cpu 0:
 __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+0x1f7/0x300 fs/namei.c:4123
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4146
 __do_sys_mkdir fs/namei.c:4166 [inline]
 __se_sys_mkdir fs/namei.c:4164 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4164
 x64_sys_call+0x10aa/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:84
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881066ac4b0 of 8 bytes by task 5173 on cpu 1:
 step_into+0x123/0x810 fs/namei.c:1846
 walk_component+0x169/0x230 fs/namei.c:2010
 lookup_last fs/namei.c:2461 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2485
 filename_lookup+0x127/0x300 fs/namei.c:2514
 user_path_at_empty+0x42/0x120 fs/namei.c:2921
 user_path_at include/linux/namei.h:57 [inline]
 __do_sys_chdir fs/open.c:558 [inline]
 __se_sys_chdir+0x4f/0x150 fs/open.c:552
 __x64_sys_chdir+0x1f/0x30 fs/open.c:552
 x64_sys_call+0x2ad7/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:81
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88810460d7f8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5173 Comm: syz-executor.1 Not tainted 6.9.0-rc4-syzkaller-00329-g48cf398f15fc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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