[dm-devel] [PATCH v2 1/1] block: fix blk_queue_split() resource exhaustion

[Jack Wang]

2016-12-23 12:45 GMT+01:00 Lars Ellenberg <lars.ellenberg at linbit.com>:
> On Fri, Dec 23, 2016 at 09:49:53AM +0100, Michael Wang wrote:
>> Dear Maintainers
>>
>> I'd like to ask for the status of this patch since we hit the
>> issue too during our testing on md raid1.
>>
>> Split remainder bio_A was queued ahead, following by bio_B for
>> lower device, at this moment raid start freezing, the loop take
>> out bio_A firstly and deliver it, which will hung since raid is
>> freezing, while the freezing never end since it waiting for
>> bio_B to finish, and bio_B is still on the queue, waiting for
>> bio_A to finish...
>>
>> We're looking for a good solution and we found this patch
>> already progressed a lot, but we can't find it on linux-next,
>> so we'd like to ask are we still planning to have this fix
>> in upstream?
>
> I don't see why not, I'd even like to have it in older kernels,
> but did not have the time and energy to push it.
>
> Thanks for the bump.
>
>         Lars
>
Hi folks,

As Michael mentioned, we hit a bug this patch is trying to fix.
Neil suggested another way to fix it.  I attached below.
I personal prefer Neil's version as it's less code change, and straight forward.

Could you share your comments, we can get one fix into mainline.

Thanks,
Jinpu
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