KCSAN: data-race in btrfs_wait_block_group_cache_progress / caching

KCSAN: data-race in btrfs_wait_block_group_cache_progress / caching_thread
Status: moderation: reported on 2020/12/07 11:38
Reported-by: syzbot+65ecef0656795c48d0b3@syzkaller.appspotmail.com
First crash: 129d, last: 1d10h

Sample crash report:

==================================================================
BUG: KCSAN: data-race in btrfs_wait_block_group_cache_progress / caching_thread

write to 0xffff8880513dd0a4 of 4 bytes by task 3042 on cpu 1:
 caching_thread+0xe4/0x870 fs/btrfs/block-group.c:671
 btrfs_work_helper+0x1e2/0x380 fs/btrfs/async-thread.c:318
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x635/0xb90 kernel/workqueue.c:2421
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8880513dd0a4 of 4 bytes by task 8455 on cpu 0:
 btrfs_block_group_done fs/btrfs/block-group.h:292 [inline]
 btrfs_wait_block_group_cache_progress+0x144/0x2c0 fs/btrfs/block-group.c:405
 find_free_extent_unclustered fs/btrfs/extent-tree.c:3741 [inline]
 do_allocation_clustered fs/btrfs/extent-tree.c:3766 [inline]
 do_allocation fs/btrfs/extent-tree.c:3775 [inline]
 find_free_extent+0xeea/0x1a30 fs/btrfs/extent-tree.c:4187
 btrfs_reserve_extent+0x118/0x2c0 fs/btrfs/extent-tree.c:4317
 btrfs_alloc_tree_block+0xfe/0x870 fs/btrfs/extent-tree.c:4718
 alloc_tree_block_no_bg_flush fs/btrfs/ctree.c:989 [inline]
 __btrfs_cow_block+0x2f2/0xac0 fs/btrfs/ctree.c:1045
 btrfs_cow_block+0x252/0x3a0 fs/btrfs/ctree.c:1490
 commit_cowonly_roots+0x91/0x5d0 fs/btrfs/transaction.c:1225
 btrfs_commit_transaction+0x93b/0x17f0 fs/btrfs/transaction.c:2275
 btrfs_commit_super+0x8f/0xa0 fs/btrfs/disk-io.c:4076
 close_ctree+0x1af/0x4ad fs/btrfs/disk-io.c:4140
 btrfs_put_super+0x21/0x30 fs/btrfs/super.c:326
 generic_shutdown_super+0xcd/0x1f0 fs/super.c:464
 kill_anon_super+0x23/0x40 fs/super.c:1055
 btrfs_kill_super+0x26/0x40 fs/btrfs/super.c:2347
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x16b/0x1a0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8455 Comm: syz-executor.2 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (19):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/23 21:05	upstream	fe75a218	52e37319	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/16 08:56	upstream	1d94330a	65a7a854	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/14 05:15	upstream	65f0d241	269d24e8	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/12 09:24	upstream	a0d54b4f	2c1f2513	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/06 02:21	upstream	6207214a	b1c228e1	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/31 16:30	upstream	f6e1ea19	79264ae3	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/27 15:17	upstream	f838f8d2	2242f77f	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/22 06:48	upstream	8653b778	04201c06	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/19 23:37	upstream	467f8165	04201c06	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/09 01:56	upstream	7d8761ba	40cc414d	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/29 02:09	upstream	67f34fa8	a0092f9d	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/23 14:53	upstream	418baf2c	878fb17a	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/13 12:40	upstream	585e5b17	4a7fa9b4	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/25 22:15	upstream	986b9eac	a1839e81	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/15 01:52	upstream	3e4fb434	fc7735a2	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/08 04:11	upstream	c85fb28b	1880b4a9	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/27 08:00	upstream	eeddbe68	5dd8aee8	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/18 08:55	upstream	10b82d51	38962c8b	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/18 04:31	upstream	4cbffc46	8247808b	.config	log	report	info	clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org