linux-kernel - Re: [dm-devel] [PATCH v2 1/1] block: fix blk_queue

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Date:   Mon, 2 Jan 2017 15:33:02 +0100
From:   Jack Wang <jack.wang.usish@...il.com>
To:     Lars Ellenberg <lars.ellenberg@...bit.com>
Cc:     Michael Wang <yun.wang@...fitbricks.com>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Mike Snitzer <snitzer@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Kosina <jkosina@...e.cz>,
        Ming Lei <ming.lei@...onical.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        NeilBrown <neilb@...e.com>, linux-kernel@...r.kernel.org,
        linux-raid <linux-raid@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.de>,
        "linux-bcache@...r.kernel.org" <linux-bcache@...r.kernel.org>,
        Zheng Liu <gnehzuil.liu@...il.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Keith Busch <keith.busch@...el.com>,
        device-mapper development <dm-devel@...hat.com>,
        Shaohua Li <shli@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Alasdair Kergon <agk@...hat.com>,
        Roland Kammerer <roland.kammerer@...bit.com>
Subject: Re: [dm-devel] [PATCH v2 1/1] block: fix blk_queue_split() resource exhaustion

2016-12-23 12:45 GMT+01:00 Lars Ellenberg <lars.ellenberg@...bit.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

View attachment "0001-block-fix-deadlock-between-freeze_array-and-wait_bar.patch" of type "text/x-patch" (2366 bytes)