KCSAN: data-race in pcpu_balance_workfn / pcpu_free

KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area (3)
Status: moderation: reported on 2020/12/07 11:46
Reported-by: syzbot+ef7a33de7d8ace59d619@syzkaller.appspotmail.com
First crash: 195d, last: 7d19h

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area				1	375d	375d	0/22	auto-closed as invalid on 2020/06/18 13:23
upstream	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area (2)				1	290d	290d	0/22	auto-closed as invalid on 2020/08/08 10:36

Sample crash report:

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

write to 0xffffffff88f3dccc of 4 bytes by task 18529 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:559 [inline]
 pcpu_block_update_hint_free mm/percpu.c:994 [inline]
 pcpu_free_area+0x597/0x640 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
 map_create kernel/bpf/syscall.c:905 [inline]
 __do_sys_bpf+0x92cb/0x99c0 kernel/bpf/syscall.c:4375
 __se_sys_bpf kernel/bpf/syscall.c:4351 [inline]
 __x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4351
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff88f3dccc of 4 bytes by task 9115 on cpu 1:
 __pcpu_balance_workfn mm/percpu.c:2002 [inline]
 pcpu_balance_workfn+0x9a2/0xf10 mm/percpu.c:2069
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9115 Comm: kworker/1:4 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events pcpu_balance_workfn
==================================================================

Crashes (32):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/04/13 12:20	upstream	89698bec	6a81331a	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/04/11 13:52	upstream	52e44129	6a81331a	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/30 00:17	upstream	1e43c377	6a81331a	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/28 07:21	upstream	0f4498ce	a8529b82	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/25 23:04	upstream	00232240	6a383ecf	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/25 17:29	upstream	e1381380	6a383ecf	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/20 05:38	upstream	8b12a62a	3d01c4de	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/17 07:25	upstream	1df27313	fdb2bb2c	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/16 00:33	upstream	1e28eed1	fdb2bb2c	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/13 17:53	upstream	f296bfd5	4a003785	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/03/09 00:49	upstream	144c79ef	09fbf400	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/21 11:26	upstream	e767b353	3e5ed8b4	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/21 04:28	upstream	f40ddce8	3e5ed8b4	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/18 10:31	upstream	f40ddce8	14052202	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/11 11:30	upstream	291009f6	a52ee10a	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/09 17:58	upstream	e0756cfc	2bd9619f	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/04 14:44	upstream	61556703	42b90a7c	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/02/01 07:23	upstream	1048ba83	fc9fd31e	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/23 19:54	upstream	fe75a218	52e37319	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/22 01:17	upstream	9791581c	d4f4eca5	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/19 15:13	upstream	1e2a199f	63631df1	.config	log	report	info	KCSAN: data-race in pcpu_balance_workfn / pcpu_free_area
ci2-upstream-kcsan-gce	2021/01/11 01:27	upstream	0653161f	2c1f2513	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/05 17:28	upstream	36bbbd0e	a0234d98	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/01 06:02	upstream	f6e1ea19	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/28 23:29	upstream	c76e02c5	8259d56c	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/27 00:00	upstream	40f78232	821e0b09	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/26 09:50	upstream	5814bc2d	821e0b09	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/20 04:53	upstream	467f8165	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/17 19:20	upstream	accefff5	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/11 07:10	upstream	eccc8767	cca87986	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/05 13:27	upstream	4ef8451b	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/07 10:22	upstream	c85fb28b	1880b4a9	.config	log	report	info