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From: Calvin Owens <calvinowens@fb.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-block@vger.kernel.org, kernel-team@fb.com,
	linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	xfs@oss.sgi.com
Subject: Re: [BUG] Slab corruption during XFS writeback under memory pressure
Date: Mon, 18 Jul 2016 19:05:44 -0700	[thread overview]
Message-ID: <24d2f83f-5281-ab3c-9e91-985a4b8e2f8b@fb.com> (raw)
In-Reply-To: <20160718060215.GB16044@dastard>

On 07/17/2016 11:02 PM, Dave Chinner wrote:
> On Sun, Jul 17, 2016 at 10:00:03AM +1000, Dave Chinner wrote:
>> On Fri, Jul 15, 2016 at 05:18:02PM -0700, Calvin Owens wrote:
>>> Hello all,
>>>
>>> I've found a nasty source of slab corruption. Based on seeing similar symptoms
>>> on boxes at Facebook, I suspect it's been around since at least 3.10.
>>>
>>> It only reproduces under memory pressure so far as I can tell: the issue seems
>>> to be that XFS reclaims pages from buffers that are still in use by
>>> scsi/block. I'm not sure which side the bug lies on, but I've only observed it
>>> with XFS.
> [....]
>> But this indicates that the page is under writeback at this point,
>> so that tends to indicate that the above freeing was incorrect.
>>
>> Hmmm - it's clear we've got direct reclaim involved here, and the
>> suspicion of a dirty page that has had it's bufferheads cleared.
>> Are there any other warnings in the log from XFS prior to kasan
>> throwing the error?
>
> Can you try the patch below?

Thanks for getting this out so quickly :)

So far so good: I booted Linus' tree as of this morning and reproduced the ASAN
splat. After applying your patch I haven't triggered it.

I'm a bit wary since it was hard to trigger reliably in the first place... so I
lined up a few dozen boxes to run the test case overnight. I'll confirm in the
morning (-0700) they look good.

Thanks,
Calvin

> -Dave.

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  reply	other threads:[~2016-07-19  2:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-16  0:18 [BUG] Slab corruption during XFS writeback under memory pressure Calvin Owens
2016-07-17  0:00 ` Dave Chinner
2016-07-18  6:02   ` Dave Chinner
2016-07-19  2:05     ` Calvin Owens [this message]
2016-07-19 21:22       ` Calvin Owens
2016-07-19 22:58         ` Dave Chinner

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