KCSAN: data-race in __dentry_kill / d_alloc

KCSAN: data-race in __dentry_kill / d_alloc_parallel (3)
Status: auto-closed as invalid on 2020/10/11 15:50
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 407d, last: 407d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __dentry_kill / d_alloc_parallel	36	623d	726d	0/22	auto-closed as invalid on 2020/04/13 06:40
upstream	KCSAN: data-race in __dentry_kill / d_alloc_parallel (2)	3	443d	475d	0/22	auto-closed as invalid on 2020/09/05 03:58
upstream	KCSAN: data-race in __dentry_kill / d_alloc_parallel (4)	1	166d	166d	0/22	auto-closed as invalid on 2021/06/09 01:27

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __dentry_kill / d_alloc_parallel

write to 0xffff8881214caa80 of 4 bytes by task 7606 on cpu 0:
 d_alloc_parallel+0xb5b/0xd10 fs/dcache.c:2631
 lookup_open fs/namei.c:3030 [inline]
 open_last_lookups fs/namei.c:3177 [inline]
 path_openat+0x665/0x20a0 fs/namei.c:3365
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881214caa80 of 4 bytes by task 7653 on cpu 1:
 dentry_unlist fs/dcache.c:544 [inline]
 __dentry_kill+0x1ef/0x450 fs/dcache.c:575
 dentry_kill fs/dcache.c:692 [inline]
 dput+0x208/0x420 fs/dcache.c:878
 handle_mounts fs/namei.c:1389 [inline]
 step_into+0x448/0xe70 fs/namei.c:1690
 open_last_lookups fs/namei.c:3200 [inline]
 path_openat+0xfaf/0x20a0 fs/namei.c:3365
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 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: 7653 Comm: systemd-udevd Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/09/06 15:44	upstream	dd9fb9bb3340	abf9ba4f	.config	log	report