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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff888109f4f900 of 4 bytes by task 25701 on cpu 0:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:2011
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:2055
 ext4_mkdir+0x5e5/0x740 fs/ext4/namei.c:3046
 vfs_mkdir+0x1ac/0x2b0 fs/namei.c:4117
 do_mkdirat+0xf9/0x260 fs/namei.c:4140
 __do_sys_mkdir fs/namei.c:4160 [inline]
 __se_sys_mkdir fs/namei.c:4158 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4158
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888109f4f900 of 4 bytes by task 25702 on cpu 1:
 d_revalidate fs/namei.c:858 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1639
 walk_component fs/namei.c:1994 [inline]
 link_path_walk+0x3f4/0x7e0 fs/namei.c:2325
 path_parentat fs/namei.c:2526 [inline]
 __filename_parentat+0x13b/0x3c0 fs/namei.c:2550
 filename_parentat fs/namei.c:2568 [inline]
 filename_create+0x77/0x2b0 fs/namei.c:3867
 do_mkdirat+0x63/0x260 fs/namei.c:4132
 __do_sys_mkdir fs/namei.c:4160 [inline]
 __se_sys_mkdir fs/namei.c:4158 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4158
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00080000 -> 0x00280040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25702 Comm: syz-executor.5 Not tainted 6.5.0-rc3-syzkaller-00297-gd31e3792919e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
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