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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff888106a60c00 of 4 bytes by task 8131 on cpu 0:
 __d_instantiate+0x2cd/0x3c0 fs/dcache.c:1855
 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_mkdirat fs/namei.c:4161 [inline]
 __se_sys_mkdirat fs/namei.c:4159 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4159
 x64_sys_call+0x22e9/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:259
 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 0xffff888106a60c00 of 4 bytes by task 8132 on cpu 1:
 __follow_mount_rcu fs/namei.c:1485 [inline]
 handle_mounts fs/namei.c:1536 [inline]
 step_into+0xe7/0x810 fs/namei.c:1842
 walk_component fs/namei.c:2010 [inline]
 link_path_walk+0x49d/0x810 fs/namei.c:2331
 path_parentat fs/namei.c:2532 [inline]
 __filename_parentat+0x13c/0x3c0 fs/namei.c:2556
 filename_parentat fs/namei.c:2574 [inline]
 filename_create+0x77/0x2b0 fs/namei.c:3873
 do_mkdirat+0x63/0x2a0 fs/namei.c:4138
 __do_sys_mkdirat fs/namei.c:4161 [inline]
 __se_sys_mkdirat fs/namei.c:4159 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4159
 x64_sys_call+0x22e9/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:259
 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: 0x00000000 -> 0x00280000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8132 Comm: syz-executor.1 Tainted: G        W          6.9.0-rc4-syzkaller-00214-g13a2e429f644 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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