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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88814438a000 of 4 bytes by task 22524 on cpu 1:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:2010
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:2054
 ext4_mkdir+0x5e5/0x740 fs/ext4/namei.c:3051
 vfs_mkdir+0x1ac/0x2b0 fs/namei.c:4121
 do_mkdirat+0xf9/0x270 fs/namei.c:4144
 __do_sys_mkdir fs/namei.c:4164 [inline]
 __se_sys_mkdir fs/namei.c:4162 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4162
 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 0xffff88814438a000 of 4 bytes by task 22528 on cpu 0:
 d_revalidate fs/namei.c:861 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1643
 walk_component+0x3f/0x230 fs/namei.c:1998
 lookup_last fs/namei.c:2459 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2483
 filename_lookup+0x126/0x300 fs/namei.c:2512
 user_path_at_empty+0x42/0x110 fs/namei.c:2911
 user_path_at include/linux/namei.h:57 [inline]
 do_fchmodat fs/open.c:689 [inline]
 __do_sys_chmod fs/open.c:715 [inline]
 __se_sys_chmod fs/open.c:713 [inline]
 __x64_sys_chmod+0x6b/0x110 fs/open.c:713
 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: 0x00000000 -> 0x00280000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22528 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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