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Subject: Re: [PATCH BUGFIX 1/1] block, bfq: add requeue-request hook
From: Mike Galbraith <efault@gmx.de>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>,
        Jens Axboe <axboe@kernel.dk>,
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        SERENA ZIVIANI <169364@studenti.unimore.it>,
        Serena Ziviani <ziviani.serena@gmail.com>,
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Date: Wed, 07 Feb 2018 11:15:16 +0100
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On Wed, 2018-02-07 at 10:45 +0100, Paolo Valente wrote:
> 
> > Il giorno 07 feb 2018, alle ore 10:23, Mike Galbraith <efault@gmx.de> ha scritto:
> > 
> > On Wed, 2018-02-07 at 10:08 +0100, Paolo Valente wrote:
> >> 
> >> The first piece of information I need is whether this failure happens
> >> even without "BFQ hierarchical scheduling support".
> > 
> > I presume you mean BFQ_GROUP_IOSCHED, which I do not have enabled.
> > 
> 
> Great (so to speak), this saves us one step.
> 
> So, here's my next request for help: please apply the attached patch
> (compressed to preserve it from my email client) and retry. It adds
> several anomaly checks. I hope I have not added any false-positive
> check.

kernel BUG at block/bfq-iosched.c:4742!

4742         BUG_ON(!(rq->rq_flags & RQF_ELVPRIV));