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Subject: Re: Regression in 5.17-rc1 on pata-falcon
To:     Geert Uytterhoeven <geert@linux-m68k.org>
References: <20220128173006.1713210-1-geert@linux-m68k.org>
 <63c80eba-7c55-2a92-8078-c63cec3c9efb@gmail.com>
 <8913a0a2-9496-143c-18c2-f3023fd37ba0@gmail.com>
 <8d215dab-cd0f-452b-281b-f67c9324b53b@gmail.com>
 <CAMuHMdVnkvSCHKt5ouZP7HrMBg7nPg7fjiio-KVJ7dehA=FwyQ@mail.gmail.com>
Cc:     linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Jens Axboe <axboe@kernel.dk>,
        Laibin Qiu <qiulaibin@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>
From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <eb5fc9ae-45a7-44d3-0238-5cdaa1ae3558@gmail.com>
Date:   Sun, 6 Feb 2022 10:59:07 +1300
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Hi Geert, Jens,

thanks for the hint - applying 10825410b956dc1e on top of 5.17-rc1 does 
indeed fix the issue.

nr_tags == 1 on the Falcon may explain why I ran into this. Oddly 
enough, I have the same on ARAnyM. Adding a second 'disk' there does 
reproduce the issue on ARAnyM though. nr_tags == 1 && nr_disks > 1 
appears to be sufficient to reproduce this.

I surmised I couldn't be the only one to run into this, but hadn't seen 
any other reports yet.

Cheers,

	Michael


Am 05.02.2022 um 21:31 schrieb Geert Uytterhoeven:
> Hi Michael,
>
> On Sat, Feb 5, 2022 at 1:04 AM Michael Schmitz <schmitzmic@gmail.com> wrote:
>> commit 180dccb0dba4f5e84a4a70c1be1d34cbb6528b32 (blk-mq: fix tag_get
>> wait task can't be awakened) does cause a regression on my m68k hardware
>> test rig (m68k Falcon030, IDE disk attached through pata-falcon driver
>> which does use polled IO instead of interrupts, so may be a little on
>> the slow side).
>
>> Bisection between v5.16 and v5.17-rc1 points to
>> 180dccb0dba4f5e84a4a70c1be1d34cbb6528b32 as the culprit, which is
>> corroborated by reverting that commit in v5.17-rc1 and booting as
>> rapidly as before.
>
> Now you know the culprit, it looks like several other people ran into this.
> Does this fix help?
> https://lore.kernel.org/all/1643040870.3bwvk3sis4.none@localhost/
>
> It is commit 10825410b956dc1e ("blk-mq: Fix wrong wakeup
> batch configuration which will cause hang") in v5.17-rc2.
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>