search for: bitmap_tags

...domo-info.html > > > Digging through the code, I think I found a possible cause: tags->rqs[..] is not initialized with zeroes (via alloc_pages_node in blk-mq.c:blk_mq_init_rq_map()). When a request is created: 1. __blk_mq_alloc_request() gets a free tag (thus e.g. removing it from bitmap_tags) 2. __blk_mq_alloc_request() initializes is via blk_mq_rq_ctx_init(). The struct is filled with life and rq->q is set. When blk_mq_hw_ctx_check_timeout() is called: 1. blk_mq_tag_busy_iter() is used to call blk_mq_timeout_check() on all busy tags. 2. This is done by collecting all free tags...

...domo-info.html > > > Digging through the code, I think I found a possible cause: tags->rqs[..] is not initialized with zeroes (via alloc_pages_node in blk-mq.c:blk_mq_init_rq_map()). When a request is created: 1. __blk_mq_alloc_request() gets a free tag (thus e.g. removing it from bitmap_tags) 2. __blk_mq_alloc_request() initializes is via blk_mq_rq_ctx_init(). The struct is filled with life and rq->q is set. When blk_mq_hw_ctx_check_timeout() is called: 1. blk_mq_tag_busy_iter() is used to call blk_mq_timeout_check() on all busy tags. 2. This is done by collecting all free tags...

On 09/12/2014 01:54 PM, Ming Lei wrote: > On Thu, Sep 11, 2014 at 6:26 PM, Christian Borntraeger > <borntraeger at de.ibm.com> wrote: >> Folks, >> >> we have seen the following bug with 3.16 as a KVM guest. It suspect the blk-mq rework that happened between 3.15 and 3.16, but it can be something completely different. >> > > Care to share how you reproduce

On 09/12/2014 01:54 PM, Ming Lei wrote: > On Thu, Sep 11, 2014 at 6:26 PM, Christian Borntraeger > <borntraeger at de.ibm.com> wrote: >> Folks, >> >> we have seen the following bug with 3.16 as a KVM guest. It suspect the blk-mq rework that happened between 3.15 and 3.16, but it can be something completely different. >> > > Care to share how you reproduce