syzbot

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BUG: KCSAN: data-race in d_lru_add / step_into

write to 0xffff88813b123540 of 4 bytes by task 22526 on cpu 0:
 d_lru_add+0x45/0xe0 fs/dcache.c:427
 retain_dentry+0x157/0x190 fs/dcache.c:685
 dput+0x108/0x1f0 fs/dcache.c:908
 done_path_create fs/namei.c:3925 [inline]
 do_mkdirat+0x139/0x2a0 fs/namei.c:4132
 __do_sys_mkdir fs/namei.c:4149 [inline]
 __se_sys_mkdir fs/namei.c:4147 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4147
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813b123540 of 4 bytes by task 22527 on cpu 1:
 __d_entry_type include/linux/dcache.h:386 [inline]
 d_is_symlink include/linux/dcache.h:416 [inline]
 step_into+0x12f/0x800 fs/namei.c:1845
 walk_component+0x164/0x230 fs/namei.c:2008
 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_mount fs/namespace.c:3674 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount+0x24b/0x2d0 fs/namespace.c:3863
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00200000 -> 0x00280040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22527 Comm: syz-executor.4 Not tainted 6.6.0-syzkaller-03860-g5a6a09e97199 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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