syzbot

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BUG: KCSAN: data-race in d_delete / step_into

read-write to 0xffff88812ccbfe40 of 4 bytes by task 6531 on cpu 0:
 d_delete+0x66/0xa0 fs/dcache.c:2476
 vfs_unlink+0x38f/0x3b0 fs/namei.c:3849
 do_unlinkat+0x28a/0x4d0 fs/namei.c:3899
 __do_sys_unlink fs/namei.c:3945 [inline]
 __se_sys_unlink fs/namei.c:3943 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3943
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812ccbfe40 of 4 bytes by task 4895 on cpu 1:
 __d_entry_type include/linux/dcache.h:392 [inline]
 d_is_symlink include/linux/dcache.h:422 [inline]
 step_into+0x158/0xe80 fs/namei.c:1695
 walk_component+0x190/0x350 fs/namei.c:1867
 lookup_last fs/namei.c:2312 [inline]
 path_lookupat+0x11d/0x550 fs/namei.c:2336
 filename_lookup+0xf2/0x380 fs/namei.c:2369
 user_path_at_empty+0x3b/0x50 fs/namei.c:2649
 do_readlinkat+0x87/0x200 fs/stat.c:407
 __do_sys_readlink fs/stat.c:440 [inline]
 __se_sys_readlink fs/stat.c:437 [inline]
 __x64_sys_readlink+0x43/0x50 fs/stat.c:437
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4895 Comm: systemd-udevd Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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