KCSAN: data-race in __d_drop / fast

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __d_drop / fast_dput (2) fs				3	939d	948d	0/26	auto-closed as invalid on 2021/10/28 07:38

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BUG: KCSAN: data-race in __d_drop / fast_dput

write to 0xffff888102ff6c10 of 8 bytes by task 22595 on cpu 1:
 __d_drop+0x13d/0x1e0 fs/dcache.c:483
 __dentry_kill+0x12f/0x4e0 fs/dcache.c:577
 shrink_dentry_list+0x1bb/0x340 fs/dcache.c:1176
 shrink_dcache_sb+0x188/0x2d0 fs/dcache.c:1296
 reconfigure_super+0x2aa/0x4f0 fs/super.c:889
 do_remount fs/namespace.c:2639 [inline]
 path_mount+0x1442/0x1ce0 fs/namespace.c:3227
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888102ff6c10 of 8 bytes by task 1771 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:342 [inline]
 fast_dput+0x92/0x1c0 fs/dcache.c:812
 dput+0x26/0x360 fs/dcache.c:875
 do_rmdir+0x162/0x2e0 fs/namei.c:3960
 __do_sys_rmdir fs/namei.c:3976 [inline]
 __se_sys_rmdir fs/namei.c:3974 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3974
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff8882378027c0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1771 Comm: syz-executor.3 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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