From: Song Liu <liu.song.a23@gmail.com>
To: "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Cc: linux-block@vger.kernel.org,
linux-raid <linux-raid@vger.kernel.org>,
dm-devel@redhat.com, axboe@kernel.dk,
Gavin Guo <gavin.guo@canonical.com>,
Jay Vosburgh <jay.vosburgh@canonical.com>,
kernel@gpiccoli.net, Ming Lei <ming.lei@redhat.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
stable@vger.kernel.org
Subject: Re: [PATCH 2/2] md/raid0: Do not bypass blocking queue entered for raid0 bios
Date: Mon, 6 May 2019 17:07:16 -0400 [thread overview]
Message-ID: <CAPhsuW6ahmkUhCgns=9WHPXSvYefB0Gmr1oB7gdZiD86sKyHFg@mail.gmail.com> (raw)
In-Reply-To: <c8721ba3-5d38-7906-5049-e2b16e967ecf@canonical.com>
On Mon, May 6, 2019 at 2:48 PM Guilherme G. Piccoli
<gpiccoli@canonical.com> wrote:
>
> On 06/05/2019 13:50, Song Liu wrote:
> > [...]
> > IIUC, we need this for all raid types. Is it possible to fix that in md.c so
> > all types get the fix?
> >
> > Thanks,
> > Song
> >
>
> Hi Song, thanks again for reviewing my code and provide input, much
> appreciated!
>
> I understand this could in theory affects all the RAID levels, but in
> practice I don't think it'll happen. RAID0 is the only "blind" mode of
> RAID, in the sense it's the only one that doesn't care at all with
> failures. In fact, this was the origin of my other thread [0], regarding
> the change of raid0's behavior in error cases..because it currently does
> not care with members being removed and rely only in filesystem failures
> (after submitting many BIOs to the removed device).
>
> That said, in this change I've only took care of raid0, since in my
> understanding the other levels won't submit BIOs to dead devices; we can
> experiment that to see if it's true.
Could you please run a quick test with raid5? I am wondering whether
some race condition could get us into similar crash. If we cannot easily
trigger the bug, we can process with this version.
Thanks,
Song
>
> But I'd be happy to change all other levels also if you think it's
> appropriate (or a simple generic change to md.c if it is enough). Do you
> think we could go ahead with this change, and further improve that (to
> cover all raid cases if necessary)?
>
> Cheers,
>
>
> Guilherme
>
>
>
> [0] https://marc.info/?l=linux-raid&m=155562509905735
next prev parent reply other threads:[~2019-05-06 21:07 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-30 22:37 [PATCH 1/2] block: Fix a NULL pointer dereference in generic_make_request() Guilherme G. Piccoli
2019-04-30 22:37 ` [PATCH 2/2] md/raid0: Do not bypass blocking queue entered for raid0 bios Guilherme G. Piccoli
2019-05-06 16:50 ` Song Liu
2019-05-06 18:48 ` Guilherme G. Piccoli
2019-05-06 21:07 ` Song Liu [this message]
2019-05-07 21:51 ` Guilherme G. Piccoli
2019-05-08 9:29 ` Wols Lists
2019-05-08 14:52 ` Guilherme G. Piccoli
2019-05-08 16:52 ` Wols Lists
2019-05-17 16:19 ` Guilherme G. Piccoli
2019-05-20 16:23 ` Song Liu
2019-05-20 19:25 ` Guilherme Piccoli
2019-04-30 22:55 ` [PATCH 1/2] block: Fix a NULL pointer dereference in generic_make_request() Bart Van Assche
2019-05-17 3:33 ` Eric Ren
2019-05-17 16:17 ` Guilherme G. Piccoli
2019-05-20 2:43 ` Eric Ren
2019-05-17 22:04 ` Ming Lei
2019-05-23 17:23 Song Liu
2019-05-23 17:23 ` [PATCH 2/2] md/raid0: Do not bypass blocking queue entered for raid0 bios Song Liu
2019-06-12 12:40 ` Guilherme Piccoli
2019-06-12 12:48 ` Greg KH
2019-06-12 16:38 ` Guilherme G. Piccoli
2019-06-12 16:37 ` Guilherme G. Piccoli
2019-06-12 16:49 ` Greg KH
2019-06-12 18:07 ` Guilherme Piccoli
2019-06-12 18:36 ` Greg KH
2019-06-12 18:43 ` Sasha Levin
2019-06-12 18:48 ` Guilherme Piccoli
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