From a865b96c513bcaeec49669010d67c40aa8e58619 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Mon, 29 May 2023 21:20:32 +0800 Subject: [PATCH] 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 Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529132037.2124527-2-yukuai1@huaweicloud.com --- drivers/md/dm-raid.c | 1 - drivers/md/md.c | 19 ++----------------- 2 files changed, 2 insertions(+), 18 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) diff --git a/drivers/md/md.c b/drivers/md/md.c index 2e38ef421d69..d445d5fb7a01 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4764,19 +4764,6 @@ action_store(struct mddev *mddev, const char *page, size_t len) if (work_pending(&mddev->del_work)) flush_workqueue(md_misc_wq); if (mddev->sync_thread) { - sector_t save_rp = mddev->reshape_position; - - mddev_unlock(mddev); - set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_unregister_thread(&mddev->sync_thread); - mddev_lock_nointr(mddev); - /* - * set RECOVERY_INTR again and restore reshape - * position in case others changed them after - * got lock, eg, reshape_position_store and - * md_check_recovery. - */ - mddev->reshape_position = save_rp; set_bit(MD_RECOVERY_INTR, &mddev->recovery); md_reap_sync_thread(mddev); } @@ -6176,7 +6163,6 @@ static void __md_stop_writes(struct mddev *mddev) flush_workqueue(md_misc_wq); if (mddev->sync_thread) { set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_unregister_thread(&mddev->sync_thread); md_reap_sync_thread(mddev); } @@ -9327,7 +9313,6 @@ void md_check_recovery(struct mddev *mddev) * ->spare_active and clear saved_raid_disk */ set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_unregister_thread(&mddev->sync_thread); md_reap_sync_thread(mddev); clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery); clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery); @@ -9363,7 +9348,6 @@ void md_check_recovery(struct mddev *mddev) goto unlock; } if (mddev->sync_thread) { - md_unregister_thread(&mddev->sync_thread); md_reap_sync_thread(mddev); goto unlock; } @@ -9443,7 +9427,8 @@ void md_reap_sync_thread(struct mddev *mddev) sector_t old_dev_sectors = mddev->dev_sectors; bool is_reshaped = false; - /* sync_thread should be unregistered, collect result */ + /* resync has finished, collect result */ + md_unregister_thread(&mddev->sync_thread); if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) && mddev->degraded != mddev->raid_disks) { -- 2.11.0