syzbot

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BUG: KCSAN: data-race in __d_drop / dput

write to 0xffff888136ac7d90 of 8 bytes by task 14180 on cpu 0:
 __d_drop+0x16a/0x240 fs/dcache.c:508
 d_invalidate+0x4c/0x1b0 fs/dcache.c:1730
 lookup_dcache fs/namei.c:1568 [inline]
 __lookup_hash+0x16c/0x180 fs/namei.c:1586
 filename_create+0x147/0x2b0 fs/namei.c:3785
 do_mknodat+0x121/0x3d0 fs/namei.c:3929
 __do_sys_mknodat fs/namei.c:3970 [inline]
 __se_sys_mknodat fs/namei.c:3967 [inline]
 __x64_sys_mknodat+0x5e/0x70 fs/namei.c:3967
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888136ac7d90 of 8 bytes by task 14186 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:334 [inline]
 fast_dput fs/dcache.c:837 [inline]
 dput+0xa4/0x1f0 fs/dcache.c:900
 handle_mounts fs/namei.c:1548 [inline]
 step_into+0x1fd/0x7d0 fs/namei.c:1831
 walk_component+0x164/0x230 fs/namei.c:1999
 lookup_last fs/namei.c:2450 [inline]
 path_lookupat+0x11d/0x2b0 fs/namei.c:2474
 filename_lookup+0x133/0x310 fs/namei.c:2503
 user_path_at_empty+0x3e/0x110 fs/namei.c:2876
 user_path_at include/linux/namei.h:57 [inline]
 __do_sys_chdir fs/open.c:514 [inline]
 __se_sys_chdir+0x56/0x150 fs/open.c:508
 __x64_sys_chdir+0x1b/0x20 fs/open.c:508
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffff88823756df68 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14186 Comm: syz-executor.3 Not tainted 6.0.0-rc1-syzkaller-00368-gf31c32efd57c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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