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| author | Yu Kuai <yukuai3@huawei.com> | 2023-05-29 21:20:32 +0800 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2023-07-27 00:13:28 -0700 |
| commit | a865b96c513bcaeec49669010d67c40aa8e58619 (patch) | |
| tree | d92d7c89a1d249ab2386f83dfde9d1a70634b62c /drivers/md/dm-raid.c | |
| parent | 51d74ec9b62f5813767a60226acaf943e26e7d7a (diff) | |
Revert "md: unlock mddev before reap sync_thread in action_store"
This reverts commit 9dfbdafda3b34e262e43e786077bab8e476a89d1.
Because it will introduce a defect that sync_thread can be running while
MD_RECOVERY_RUNNING is cleared, which will cause some unexpected problems,
for example:
list_add corruption. prev->next should be next (ffff0001ac1daba0), but was ffff0000ce1a02a0. (prev=ffff0000ce1a02a0).
Call trace:
__list_add_valid+0xfc/0x140
insert_work+0x78/0x1a0
__queue_work+0x500/0xcf4
queue_work_on+0xe8/0x12c
md_check_recovery+0xa34/0xf30
raid10d+0xb8/0x900 [raid10]
md_thread+0x16c/0x2cc
kthread+0x1a4/0x1ec
ret_from_fork+0x10/0x18
This is because work is requeued while it's still inside workqueue:
t1: t2:
action_store
mddev_lock
if (mddev->sync_thread)
mddev_unlock
md_unregister_thread
// first sync_thread is done
md_check_recovery
mddev_try_lock
/*
* once MD_RECOVERY_DONE is set, new sync_thread
* can start.
*/
set_bit(MD_RECOVERY_RUNNING, &mddev->recovery)
INIT_WORK(&mddev->del_work, md_start_sync)
queue_work(md_misc_wq, &mddev->del_work)
test_and_set_bit(WORK_STRUCT_PENDING_BIT, ...)
// set pending bit
insert_work
list_add_tail
mddev_unlock
mddev_lock_nointr
md_reap_sync_thread
// MD_RECOVERY_RUNNING is cleared
mddev_unlock
t3:
// before queued work started from t2
md_check_recovery
// MD_RECOVERY_RUNNING is not set, a new sync_thread can be started
INIT_WORK(&mddev->del_work, md_start_sync)
work->data = 0
// work pending bit is cleared
queue_work(md_misc_wq, &mddev->del_work)
insert_work
list_add_tail
// list is corrupted
The above commit is reverted to fix the problem, the deadlock this
commit tries to fix will be fixed in following patches.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230529132037.2124527-2-yukuai1@huaweicloud.com
Diffstat (limited to 'drivers/md/dm-raid.c')
| -rw-r--r-- | drivers/md/dm-raid.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index 8846bf510a35..1f22bef27841 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -3725,7 +3725,6 @@ static int raid_message(struct dm_target *ti, unsigned int argc, char **argv, if (!strcasecmp(argv[0], "idle") || !strcasecmp(argv[0], "frozen")) { if (mddev->sync_thread) { set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_unregister_thread(&mddev->sync_thread); md_reap_sync_thread(mddev); } } else if (decipher_sync_action(mddev, mddev->recovery) != st_idle) |