From: Lars Ellenberg <lars.ellenberg@linbit.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
Jack Wang <jinpu.wang@profitbricks.com>,
NeilBrown <neilb@suse.com>, LKML <linux-kernel@vger.kernel.org>,
Kent Overstreet <kent.overstreet@gmail.com>,
Pavel Machek <pavel@ucw.cz>,
Mikulas Patocka <mpatocka@redhat.com>
Subject: Re: blk: improve order of bio handling in generic_make_request()
Date: Wed, 8 Mar 2017 12:46:33 +0100 [thread overview]
Message-ID: <CANr6vz_Hz7gRdcBFCaetEuQNEX8e9UHNUcnHRoMiw1h7ietthQ@mail.gmail.com> (raw)
In-Reply-To: <20170307165233.GB30230@redhat.com>
On 7 March 2017 at 17:52, Mike Snitzer <snitzer@redhat.com> wrote:
> > On 06.03.2017 21:18, Jens Axboe wrote:
> > > I like the change, and thanks for tackling this. It's been a pending
> > > issue for way too long. I do think we should squash Jack's patch
> > > into the original, as it does clean up the code nicely.
> > >
> > > Do we have a proper test case for this, so we can verify that it
> > > does indeed also work in practice?
> > >
> > Hi Jens,
> >
> > I can trigger deadlock with in RAID1 with test below:
> >
> > I create one md with one local loop device and one remote scsi
> > exported by SRP. running fio with mix rw on top of md, force_close
> > session on storage side. mdx_raid1 is wait on free_array in D state,
> > and a lot of fio also in D state in wait_barrier.
> >
> > With the patch from Neil above, I can no longer trigger it anymore.
> >
> > The discussion was in link below:
> > http://www.spinics.net/lists/raid/msg54680.html
>
> In addition to Jack's MD raid test there is a DM snapshot deadlock test,
> albeit unpolished/needy to get running, see:
> https://www.redhat.com/archives/dm-devel/2017-January/msg00064.html
>
> But to actually test block core's ability to handle this, upstream
> commit d67a5f4b5947aba4bfe9a80a2b86079c215ca755 ("dm: flush queued bios
> when process blocks to avoid deadlock") would need to be reverted.
>
> Also, I know Lars had a drbd deadlock too. Not sure if Jack's MD test
> is sufficient to coverage for drbd. Lars?
>
As this is just a slightly different implementation, trading some bytes of
stack
for more local, self-contained, "obvious" code changes (good job!),
but follows the same basic idea as my original RFC [*] (see the
"inspired-by" tag)
I have no doubt it fixes the issues we are able to provoke with DRBD.
[*] https://lkml.org/lkml/2016/7/19/263
(where I also already suggest to fix the device-mapper issues
by losing the in-device-mapper loop,
relying on the loop in generic_make_request())
Cheers,
Lars
next prev parent reply other threads:[~2017-03-08 12:52 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-03 5:14 [PATCH] blk: improve order of bio handling in generic_make_request() NeilBrown
2017-03-03 9:28 ` Jack Wang
2017-03-06 4:40 ` NeilBrown
2017-03-06 9:43 ` Jack Wang
2017-03-07 15:46 ` Pavel Machek
2017-03-07 15:53 ` Jack Wang
2017-03-07 16:21 ` Jens Axboe
2017-03-06 20:18 ` Jens Axboe
2017-03-07 8:49 ` Jack Wang
2017-03-07 16:52 ` Mike Snitzer
2017-03-07 17:05 ` Jens Axboe
2017-03-07 17:14 ` Mike Snitzer
2017-03-07 20:29 ` NeilBrown
2017-03-07 23:01 ` Mike Snitzer
2017-03-08 16:40 ` Mikulas Patocka
2017-03-08 17:15 ` Lars Ellenberg
2017-03-09 6:08 ` NeilBrown
2017-03-08 11:46 ` Lars Ellenberg [this message]
2017-03-07 20:38 ` [PATCH v2] " NeilBrown
2017-03-10 4:32 ` NeilBrown
2017-03-10 4:33 ` [PATCH 1/5 v3] " NeilBrown
2017-03-10 4:34 ` [PATCH 2/5] blk: remove bio_set arg from blk_queue_split() NeilBrown
2017-03-10 4:35 ` [PATCH 3/5] blk: make the bioset rescue_workqueue optional NeilBrown
2017-03-10 4:36 ` [PATCH 4/5] blk: use non-rescuing bioset for q->bio_split NeilBrown
2017-03-10 4:37 ` [PATCH 5/5] block_dev: make blkdev_dio_pool a non-rescuing bioset NeilBrown
2017-03-10 4:38 ` [PATCH v2] blk: improve order of bio handling in generic_make_request() Jens Axboe
2017-03-10 4:40 ` Jens Axboe
2017-03-10 5:19 ` NeilBrown
2017-03-10 12:34 ` Lars Ellenberg
2017-03-10 14:38 ` Mike Snitzer
2017-03-10 14:55 ` Mikulas Patocka
2017-03-10 15:07 ` Jack Wang
2017-03-10 15:35 ` Mike Snitzer
2017-03-10 18:51 ` Lars Ellenberg
2017-03-11 0:47 ` NeilBrown
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