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Subject: Re: Bisected GFP in bfq_bfqq_expire on v5.1-rc1
From:   Paolo Valente <paolo.valente@linaro.org>
In-Reply-To: <0e203a26-b941-cef4-dff1-013999d4b041@kernel.dk>
Date:   Mon, 1 Apr 2019 09:29:16 +0200
Cc:     Dmitrii Tcvetkov <demfloro@demfloro.ru>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
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Message-Id: <626EAE58-63C1-4ABA-9040-9D9A61F74A0D@linaro.org>
References: <20190329160227.7d55c8dd@fire.localdomain>
 <0e203a26-b941-cef4-dff1-013999d4b041@kernel.dk>
To:     Jens Axboe <axboe@kernel.dk>
Sender: linux-kernel-owner@vger.kernel.org
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> Il giorno 29 mar 2019, alle ore 15:10, Jens Axboe <axboe@kernel.dk> ha =
scritto:
>=20
> On 3/29/19 7:02 AM, Dmitrii Tcvetkov wrote:
>> Hi,
>>=20
>> I got kernel panic since v5.1-rc1 when working with files on block
>> device with BFQ scheduler assigned. I didn't find trivial way to
>> reproduce the panic but "git checkout origin/linux-5.0.y"
>> on linux-stable-rc[1] git repo on btrfs filesystem reproduces the
>> problem 100% of the time on my bare-metal machine and in a VM.
>>=20
>> Bisect led me to commit 9dee8b3b057e1 (block, bfq: fix queue removal
>> from weights tree). After reverting this commit on top of current
>> mainline master(9936328b41ce) I can't reproduce the problem.
>>=20
>> dmesg with the panic and bisect log attached.
>>=20
>> [1] =
https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stab=
le-rc.git
>=20
> Paolo, can you please take a look at this?
>=20
>=20

Yep.

That you very much Dmitrii for also bisecting.  I feel like this
failure may be caused by the typo fixed by this patch:
https://patchwork.kernel.org/patch/10877113/

Could you please give this fix a try?

Thanks,
Paolo


> --=20
> Jens Axboe