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Subject: Re: linux-next: Tree for Aug 1
To:     Ming Lei <tom.leiming@gmail.com>
Cc:     James Bottomley <James.Bottomley@hansenpartnership.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-scsi <linux-scsi@vger.kernel.org>
References: <20180801175852.36549130@canb.auug.org.au>
 <20180801224813.GA13074@roeck-us.net>
 <1533163965.3158.1.camel@HansenPartnership.com>
 <20180801234727.GA3762@roeck-us.net>
 <CACVXFVMrzLRP5Q=cwZGnqeUeyODL3Pq9jMkT7czZouK9510fUA@mail.gmail.com>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <b113950e-26d6-e872-1a1e-c199c4fb2dcc@roeck-us.net>
Date:   Wed, 1 Aug 2018 17:12:26 -0700
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On 08/01/2018 04:57 PM, Ming Lei wrote:
> On Thu, Aug 2, 2018 at 7:47 AM, Guenter Roeck <linux@roeck-us.net> wrote:
>> On Wed, Aug 01, 2018 at 03:52:45PM -0700, James Bottomley wrote:
>>> On Wed, 2018-08-01 at 15:48 -0700, Guenter Roeck wrote:
>>>> On Wed, Aug 01, 2018 at 05:58:52PM +1000, Stephen Rothwell wrote:
>>>>> Hi all,
>>>>>
>>>>> Changes since 20180731:
>>>>>
>>>>> The pci tree gained a conflict against the pci-current tree.
>>>>>
>>>>> The net-next tree gained a conflict against the bpf tree.
>>>>>
>>>>> The block tree lost its build failure.
>>>>>
>>>>> The staging tree still had its build failure due to an interaction
>>>>> with
>>>>> the vfs tree for which I disabled CONFIG_EROFS_FS.
>>>>>
>>>>> The kspp tree lost its build failure.
>>>>>
>>>>> Non-merge commits (relative to Linus' tree): 10070
>>>>>   9137 files changed, 417605 insertions(+), 179996 deletions(-)
>>>>>
>>>>> -----------------------------------------------------------------
>>>>> -----------
>>>>>
>>>>
>>>> The widespread kernel hang issues are still seen. I managed
>>>> to bisect it after working around the transient build failures.
>>>> Bisect log is attached below. Unfortunately, it doesn't help much.
>>>> The culprit is reported as:
>>>>
>>>> 2d542828c5e9 Merge remote-tracking branch 'scsi/for-next'
>>>>
>>>> The preceding merge,
>>>>
>>>> 453f1d821165 Merge remote-tracking branch 'cgroup/for-next'
>>>>
>>>> checks out fine, as does the tip of scsi-next (commit 103c7b7e0184,
>>>> "Merge branch 'misc' into for-next"). No idea how to proceed.
>>>
>>> This sounds like you may have a problem with this patch:
>>>
>>>      commit d5038a13eca72fb216c07eb717169092e92284f1
>>>       Author: Johannes Thumshirn <jthumshirn@suse.de>
>>>       Date:   Wed Jul 4 10:53:56 2018 +0200
>>>
>>>           scsi: core: switch to scsi-mq by default
>>>
>>> To verify, boot with the additional kernel parameter
>>>
>>> scsi_mod.use_blk_mq=0
>>>
>>> Which will reverse the effect of the above patch.
>>>
>> Yes, that fixes the problem.
> 
> That may not the root cause, given this issue is only started to
> see from next-20180731, but d5038a13eca7 (scsi: core: switch to
> scsi-mq by default)
> has been in -next for quite a while.
> 
> Seems something new causes this issue.
> 

Agreed. I should have said "fixes the symptom". I'll try to bisect
with scsi_mod.use_blk_mq=1 as suggested by James.

Guenter