Re: blk-mq crash under KVM in multiqueue block code (with virtio-blk and ext4)

On 09/17/2014 01:09 PM, David Hildenbrand wrote:

quoted

quoted

0. That should already be sufficient to hinder blk_mq_tag_to_rq and the calling
method to do the wrong thing.

Yes, clearing rq->cmd_flags should be enough.

And looks better to move rq initialization to __blk_mq_free_request()
too, otherwise timeout still may see old cmd_flags and rq->q before
rq's new initialization.

Yes, __blk_mq_free_request() should also reset at least rq->cmd_flags, and I
think we can remove the initialization from  __blk_mq_alloc_request().

And then we come full circle, that's how the code originally started out
(and it is the saner way to do things). So yes, I'd greatly applaud that.


-- 
Jens Axboe