KCSAN: data-race in d_alloc_parallel / d_set_d

KCSAN: data-race in d_alloc_parallel / d_set_d_op (3)
Status: auto-closed as invalid on 2021/01/03 18:19
Reported-by: syzbot+c564fa9f48ce68aff141@syzkaller.appspotmail.com
First crash: 248d, last: 236d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in d_alloc_parallel / d_set_d_op (4)	1	173d	173d	0/22	auto-closed as invalid on 2021/03/08 01:09
upstream	KCSAN: data-race in d_alloc_parallel / d_set_d_op	23	470d	634d	0/22	auto-closed as invalid on 2020/06/18 13:33
upstream	KCSAN: data-race in d_alloc_parallel / d_set_d_op (2)	1	333d	333d	0/22	auto-closed as invalid on 2020/09/29 03:57
upstream	KCSAN: data-race in d_alloc_parallel / d_set_d_op (5)	13	43d	132d	0/22	auto-closed as invalid on 2021/07/16 11:19

Sample crash report:

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

read-write to 0xffff888037646240 of 4 bytes by task 4891 on cpu 0:
 d_set_d_op+0x14c/0x1e0 fs/dcache.c:1875
 simple_lookup+0x78/0x90 fs/libfs.c:73
 lookup_open fs/namei.c:3083 [inline]
 open_last_lookups fs/namei.c:3178 [inline]
 path_openat+0xb8f/0x20a0 fs/namei.c:3366
 do_filp_open+0xbd/0x1d0 fs/namei.c:3396
 do_sys_openat2+0xa3/0x240 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 0xffff888037646240 of 4 bytes by task 5160 on cpu 1:
 d_in_lookup include/linux/dcache.h:362 [inline]
 d_wait_lookup fs/dcache.c:2521 [inline]
 d_alloc_parallel+0x60e/0xcc0 fs/dcache.c:2609
 lookup_open fs/namei.c:3031 [inline]
 open_last_lookups fs/namei.c:3178 [inline]
 path_openat+0x682/0x20a0 fs/namei.c:3366
 do_filp_open+0xbd/0x1d0 fs/namei.c:3396
 do_sys_openat2+0xa3/0x240 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: 5160 Comm: systemd-udevd Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/11/29 18:18	upstream	aae5ab854e38	a0092f9d	.config	log	report			info
ci2-upstream-kcsan-gce	2020/11/17 18:56	upstream	9c87c9f41245	bd2a760b	.config	log	report			info