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[PATCH] blk-mq: clear q->mq_ops if init fail

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[PATCH] blk-mq: clear q->mq_ops if init fail

Ming Lin-2
From: Ming Lin <[hidden email]>

blk_mq_init_queue() calls blk_mq_init_allocated_queue(), but q->mq_ops
was not cleared when blk_mq_init_allocated_queue() fails.
Then blk_cleanup_queue() calls blk_mq_free_queue() which will crash because:
- q->all_q_node is not added to all_q_list yet
- q->tag_set is NULL
- hctx was not setup yet or already freed

Fixed it by clearing q->mq_ops on error path.

Signed-off-by: Ming Lin <[hidden email]>
---
 block/blk-mq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 67bf8ed..86f08b1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2054,7 +2054,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 
  q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
  if (!q->queue_ctx)
- return ERR_PTR(-ENOMEM);
+ goto err_exit;
 
  q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
  GFP_KERNEL, set->numa_node);
@@ -2118,6 +2118,8 @@ err_map:
  kfree(q->queue_hw_ctx);
 err_percpu:
  free_percpu(q->queue_ctx);
+err_exit:
+ q->mq_ops = NULL;
  return ERR_PTR(-ENOMEM);
 }
 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
--
1.9.1

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Re: [PATCH] blk-mq: clear q->mq_ops if init fail

Christoph Hellwig-2
On Wed, May 25, 2016 at 11:23:27PM -0700, Ming Lin wrote:

> From: Ming Lin <[hidden email]>
>
> blk_mq_init_queue() calls blk_mq_init_allocated_queue(), but q->mq_ops
> was not cleared when blk_mq_init_allocated_queue() fails.
> Then blk_cleanup_queue() calls blk_mq_free_queue() which will crash because:
> - q->all_q_node is not added to all_q_list yet
> - q->tag_set is NULL
> - hctx was not setup yet or already freed
>
> Fixed it by clearing q->mq_ops on error path.

Looks fine,

Reviewed-by: Christoph Hellwig <[hidden email]>
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Re: [PATCH] blk-mq: clear q->mq_ops if init fail

Jens Axboe-4
In reply to this post by Ming Lin-2
On 05/26/2016 12:23 AM, Ming Lin wrote:

> From: Ming Lin <[hidden email]>
>
> blk_mq_init_queue() calls blk_mq_init_allocated_queue(), but q->mq_ops
> was not cleared when blk_mq_init_allocated_queue() fails.
> Then blk_cleanup_queue() calls blk_mq_free_queue() which will crash because:
> - q->all_q_node is not added to all_q_list yet
> - q->tag_set is NULL
> - hctx was not setup yet or already freed
>
> Fixed it by clearing q->mq_ops on error path.

Thanks Ming, applied for this series.

--
Jens Axboe

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