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Date:   Tue, 11 Sep 2018 18:16:38 +0200
Message-ID: <s5hy3c8j9g9.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Paolo Valente <paolo.valente@linaro.org>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [REGRESSION] bfq probe failed on 4.19-rc3
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On Tue, 11 Sep 2018 18:11:43 +0200,
Takashi Iwai wrote:
> 
> On Tue, 11 Sep 2018 18:09:44 +0200,
> Jens Axboe wrote:
> > 
> > On 9/11/18 10:03 AM, Takashi Iwai wrote:
> > > Hi,
> > > 
> > > I noticed that bfq doesn't appear in the I/O scheduler list on
> > > 4.19-rc3.  It seems that blkcg_policy_register() at the beginning of
> > > bfq_init() returns -ENOSPC, hence the probe aborts silently.
> > > 
> > > Is this already addressed?
> > 
> > Haven't heard about this one before. What kernel did you last use that
> > worked?
> 
> IIRC, 4.18 worked fine.  Let me see whether I have a backup...

Confirmed that 4.18 worked.  It's also with CONFIG_IOSCHED_BFQ=y and
CONFIG_BFQ_GROUP_IOSCHED=y.

And, 4.19-rc3 with CONFIG_BFQ_GROUP_IOSCHED=n seems working, too (as
expected from the error above).


(BTW I'll have to leave from this machine now.  For any further
 inquiry, I'll check tomorrow, sorry.)

Takashi