KCSAN: data-race in pcpu_alloc / pcpu_free

KCSAN: data-race in pcpu_alloc / pcpu_free_area (2)
Status: upstream: reported on 2019/11/07 18:55
Reported-by: syzbot+0b3bfb9cbec193033650@syzkaller.appspotmail.com
First crash: 496d, last: 5d23h

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in pcpu_alloc / pcpu_free_area				2	505d	514d	0/21	closed as invalid on 2019/10/15 15:50

Sample crash report:

==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

write to 0xffffffff88f48ccc of 4 bytes by task 4828 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:559 [inline]
 pcpu_block_update_hint_free mm/percpu.c:994 [inline]
 pcpu_free_area+0x578/0x620 mm/percpu.c:1254
 free_percpu+0x1cb/0x740 mm/percpu.c:2102
 htab_free_elems kernel/bpf/hashtab.c:243 [inline]
 prealloc_destroy+0xee/0x1a0 kernel/bpf/hashtab.c:337
 htab_map_free+0x45/0x340 kernel/bpf/hashtab.c:1373
 bpf_map_free_deferred+0xb2/0x110 kernel/bpf/syscall.c:459
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffffffff88f48ccc of 4 bytes by task 10655 on cpu 0:
 pcpu_alloc+0xaed/0x1090 mm/percpu.c:1835
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1894
 bpf_map_alloc_percpu+0xab/0x120 kernel/bpf/syscall.c:435
 prealloc_init kernel/bpf/hashtab.c:296 [inline]
 htab_map_alloc+0x814/0xc80 kernel/bpf/hashtab.c:508
 find_and_alloc_map kernel/bpf/syscall.c:122 [inline]
 map_create kernel/bpf/syscall.c:828 [inline]
 __do_sys_bpf+0x420c/0x9990 kernel/bpf/syscall.c:4370
 __se_sys_bpf kernel/bpf/syscall.c:4346 [inline]
 __x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4346
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10655 Comm: syz-executor.4 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (505):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/02/24 05:48	upstream	c03c21ba	fcc6d71b	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/23 04:07	upstream	b12b4724	fcc6d71b	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/22 13:15	upstream	31caf8b2	c26fb06b	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/21 05:27	upstream	e767b353	3e5ed8b4	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/17 08:35	upstream	f40ddce8	052f8d9f	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/14 12:23	upstream	358fecee	98682e5e	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/13 08:55	upstream	c6d8570e	98682e5e	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/11 18:21	upstream	291009f6	a5f86b15	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/10 21:53	upstream	291009f6	a52ee10a	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/10 09:10	upstream	e0756cfc	9c8b8541	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/08 11:37	upstream	92bf2261	2ce644fc	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/07 08:36	upstream	825b5991	2ce644fc	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/05 13:14	upstream	dd86e7fa	23a562df	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/04 10:27	upstream	61556703	624dad51	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/01 02:47	upstream	1048ba83	fc9fd31e	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/31 11:49	upstream	6642d600	fc9fd31e	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/29 19:56	upstream	bec4c296	fc9fd31e	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/28 18:34	upstream	76c057c8	7df34f59	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/27 18:30	upstream	2ab38c17	a57db36f	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/27 07:02	upstream	2ab38c17	a0ebf917	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/25 22:38	upstream	f8ad8187	52e37319	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/25 09:06	upstream	6ee1d745	52e37319	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/23 23:38	upstream	e1ae4b0b	52e37319	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/23 10:24	upstream	fe75a218	52e37319	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/22 04:30	upstream	83d09ad4	d4f4eca5	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/20 05:36	upstream	45dfb8a5	63631df1	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/18 15:29	upstream	19c329f6	63631df1	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/18 07:08	upstream	19c329f6	fd103621	.config	log	report	info	KCSAN: data-race in pcpu_alloc / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/15 19:19	upstream	5ee88057	65a7a854	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/14 22:57	upstream	14662050	468dbb55	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/13 21:40	upstream	65f0d241	a945f0a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/13 11:50	upstream	e609571b	a945f0a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/12 19:15	upstream	e609571b	0cdd6185	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/10 21:04	upstream	0653161f	2c1f2513	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/09 23:05	upstream	2ff90100	2c1f2513	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/08 22:31	upstream	6279d812	c104d4a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/06 13:16	upstream	9f1abbe9	fff20c29	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/05 22:33	upstream	6207214a	b1c228e1	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/05 21:20	upstream	6207214a	a0234d98	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/05 10:59	upstream	36bbbd0e	a0234d98	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/04 04:23	upstream	e71ba945	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/02 21:27	upstream	3516bd72	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/02 00:13	upstream	eda809ae	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/31 14:29	upstream	f6e1ea19	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/31 02:29	upstream	f6e1ea19	5cc121d6	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/30 14:01	upstream	139711f0	ecb8c012	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/30 03:52	upstream	139711f0	0fa352f2	.config	log	report	info
ci2-upstream-kcsan-gce	2019/10/23 05:09	https://github.com/google/ktsan.git kcsan	05f22368	d0686497	.config	log	report