On 08/15/2016 09:53 AM, Bart Van Assche wrote:
On 08/02/2016 10:21 AM, Jens Axboe wrote:
On 08/02/2016 06:58 AM, Jinpu Wang wrote:
Hi Jens,
I found in blk_mq_register_disk, we blk_mq_disable_hotplug which in
turn mutex_lock(&all_q_mutex);
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_register_hctx(hctx);
if (ret)
break; /// if about error out, we will call
unregister below
}
if (ret)
blk_mq_unregister_disk(disk);
In blk_mq_unregister_disk, we will try to disable_hotplug again, which
leads to dead lock.
Did I miss anything?
Nope, your analysis looks correct. This should fix it:
http://git.kernel.dk/cgit/linux-block/commit/?h=for-linus&id=6316338a94b2319abe9d3790eb9cdc56ef81ac1a
Hi Jens,
Will that patch be included in stable kernels? I just encountered a
deadlock with kernel v4.7 that looks similar.
Sure, we can push to stable, it's a pretty straight forward patch. Can
you reproduce at will? Would be nice to know if it hit the error case,
which is where it would hang.
--
Jens Axboe
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