6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ming Lei <ming.lei@xxxxxxxxxx>
commit 224749be6c23efe7fb8a030854f4fc5d1dd813b3 upstream.
This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2.
Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and
acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp
callback registering out of q->sysfs_lock"), and causes the original resctrl
lockdep warning.
So revert it and we need to fix the issue in another way.
Cc: Nilay Shroff <nilay@xxxxxxxxxxxxx>
Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20241218101617.3275704-2-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-mq-sysfs.c | 16 ++++++++++------
block/blk-mq.c | 29 +++++++++++------------------
block/blk-sysfs.c | 4 ++--
3 files changed, 23 insertions(+), 26 deletions(-)
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -275,13 +275,15 @@ void blk_mq_sysfs_unregister_hctxs(struc
struct blk_mq_hw_ctx *hctx;
unsigned long i;
- lockdep_assert_held(&q->sysfs_dir_lock);
-
+ mutex_lock(&q->sysfs_dir_lock);
if (!q->mq_sysfs_init_done)
- return;
+ goto unlock;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
+
+unlock:
+ mutex_unlock(&q->sysfs_dir_lock);
}
int blk_mq_sysfs_register_hctxs(struct request_queue *q)
@@ -290,10 +292,9 @@ int blk_mq_sysfs_register_hctxs(struct r
unsigned long i;
int ret = 0;
- lockdep_assert_held(&q->sysfs_dir_lock);
-
+ mutex_lock(&q->sysfs_dir_lock);
if (!q->mq_sysfs_init_done)
- return ret;
+ goto unlock;
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_register_hctx(hctx);
@@ -301,5 +302,8 @@ int blk_mq_sysfs_register_hctxs(struct r
break;
}
+unlock:
+ mutex_unlock(&q->sysfs_dir_lock);
+
return ret;
}
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4462,8 +4462,7 @@ static void blk_mq_realloc_hw_ctxs(struc
unsigned long i, j;
/* protect against switching io scheduler */
- lockdep_assert_held(&q->sysfs_lock);
-
+ mutex_lock(&q->sysfs_lock);
for (i = 0; i < set->nr_hw_queues; i++) {
int old_node;
int node = blk_mq_get_hctx_node(set, i);
@@ -4496,6 +4495,7 @@ static void blk_mq_realloc_hw_ctxs(struc
xa_for_each_start(&q->hctx_table, j, hctx, j)
blk_mq_exit_hctx(q, set, hctx, j);
+ mutex_unlock(&q->sysfs_lock);
/* unregister cpuhp callbacks for exited hctxs */
blk_mq_remove_hw_queues_cpuhp(q);
@@ -4527,14 +4527,10 @@ int blk_mq_init_allocated_queue(struct b
xa_init(&q->hctx_table);
- mutex_lock(&q->sysfs_lock);
-
blk_mq_realloc_hw_ctxs(set, q);
if (!q->nr_hw_queues)
goto err_hctxs;
- mutex_unlock(&q->sysfs_lock);
-
INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
@@ -4553,7 +4549,6 @@ int blk_mq_init_allocated_queue(struct b
return 0;
err_hctxs:
- mutex_unlock(&q->sysfs_lock);
blk_mq_release(q);
err_exit:
q->mq_ops = NULL;
@@ -4934,12 +4929,12 @@ static bool blk_mq_elv_switch_none(struc
return false;
/* q->elevator needs protection from ->sysfs_lock */
- lockdep_assert_held(&q->sysfs_lock);
+ mutex_lock(&q->sysfs_lock);
/* the check has to be done with holding sysfs_lock */
if (!q->elevator) {
kfree(qe);
- goto out;
+ goto unlock;
}
INIT_LIST_HEAD(&qe->node);
@@ -4949,7 +4944,9 @@ static bool blk_mq_elv_switch_none(struc
__elevator_get(qe->type);
list_add(&qe->node, head);
elevator_disable(q);
-out:
+unlock:
+ mutex_unlock(&q->sysfs_lock);
+
return true;
}
@@ -4978,9 +4975,11 @@ static void blk_mq_elv_switch_back(struc
list_del(&qe->node);
kfree(qe);
+ mutex_lock(&q->sysfs_lock);
elevator_switch(q, t);
/* drop the reference acquired in blk_mq_elv_switch_none */
elevator_put(t);
+ mutex_unlock(&q->sysfs_lock);
}
static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
@@ -5000,11 +4999,8 @@ static void __blk_mq_update_nr_hw_queues
if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
return;
- list_for_each_entry(q, &set->tag_list, tag_set_list) {
- mutex_lock(&q->sysfs_dir_lock);
- mutex_lock(&q->sysfs_lock);
+ list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_freeze_queue(q);
- }
/*
* Switch IO scheduler to 'none', cleaning up the data associated
* with the previous scheduler. We will switch back once we are done
@@ -5060,11 +5056,8 @@ switch_back:
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_elv_switch_back(&head, q);
- list_for_each_entry(q, &set->tag_list, tag_set_list) {
+ list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_unfreeze_queue(q);
- mutex_unlock(&q->sysfs_lock);
- mutex_unlock(&q->sysfs_dir_lock);
- }
/* Free the excess tags when nr_hw_queues shrink. */
for (i = set->nr_hw_queues; i < prev_nr_hw_queues; i++)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -690,11 +690,11 @@ queue_attr_store(struct kobject *kobj, s
return res;
}
- mutex_lock(&q->sysfs_lock);
blk_mq_freeze_queue(q);
+ mutex_lock(&q->sysfs_lock);
res = entry->store(disk, page, length);
- blk_mq_unfreeze_queue(q);
mutex_unlock(&q->sysfs_lock);
+ blk_mq_unfreeze_queue(q);
return res;
}
