From: "Michael L. Semon" <mlsemon35@gmail.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Mark Tinguely <tinguely@sgi.com>, xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: xfs_alloc_fix_minleft can underflow near ENOSPC
Date: Wed, 18 Feb 2015 10:32:27 -0500 [thread overview]
Message-ID: <54E4B08B.5050801@gmail.com> (raw)
In-Reply-To: <20150218004838.GM4251@dastard>
On 02/17/15 19:48, Dave Chinner wrote:
> On Tue, Feb 17, 2015 at 10:36:54AM -0500, Michael L. Semon wrote:
>> On 02/16/15 18:17, Dave Chinner wrote:
>>> On Mon, Feb 16, 2015 at 11:35:50AM -0600, Mark Tinguely wrote:
>>>> Thanks Michael, you don't need to hold your test box for me. I do
>>>> have a way to recreate these ABBA AGF buffer allocation deadlocks
>>>> and understand the whys and hows very well. I don't have a community
>>>> way to make a xfstest for it but I think your test is getting close.
>>>
>>> If you know what is causing them, then please explain how it occurs
>>> and how you think it needs to be fixed. Just telling us that you know
>>> something that we don't doesn't help us solve the problem. :(
>>>
>>> In general, the use of the args->firstblock is supposed to avoid the
>>> ABBA locking order issues with multiple allocations in the one
>>> transaction by preventing AG selection loops from looping back into
>>> AGs with a lower index than the first allocation that was made.
>>>
>>> So if you are seeing deadlocks, then it may be that we aren't
>>> following this constraint correctly in all locations....
>>
>> Will this be a classic deadlock that will cause problems when trying to
>> kill processes and unmount filesystems? If so, then I was unable to use
>> generic/224 to trigger a deadlock. If not, then I'll need a better way
>> of looking at the problem.
>
> Yes, it will hang the filesystem.
>
> Cheers,
>
> Dave.
Thanks. I'll try again tonight.
Last night's attempt was a combination of fio, fsstress, and a shell loop
of xfs_io's fcollapse command, all at once on an SSD. At the end of the
night, XFS was laughing at me. Therefore, I added the same test on the
3-partition RAID-0 side. This morning, XFS is still laughing at me, but
the RAID-0 test is still running.
Thanks!
Michael
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next prev parent reply other threads:[~2015-02-18 15:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-12 23:14 [PATCH] xfs: xfs_alloc_fix_minleft can underflow near ENOSPC Dave Chinner
2015-02-13 23:40 ` Mark Tinguely
2015-02-14 23:29 ` Dave Chinner
2015-02-16 3:39 ` Michael L. Semon
2015-02-16 17:35 ` Mark Tinguely
2015-02-16 23:17 ` Dave Chinner
2015-02-17 15:36 ` Michael L. Semon
2015-02-18 0:48 ` Dave Chinner
2015-02-18 15:32 ` Michael L. Semon [this message]
2015-02-16 13:41 ` Brian Foster
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