linux-kernel - Re: [PATCH] Fix guest memory leak and panic

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Message-Id: <20111018.151228.2056792649526003804.davem@davemloft.net>
Date:	Tue, 18 Oct 2011 15:12:28 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	krkumar2@...ibm.com
Cc:	rusty@...tcorp.com.au, mst@...hat.com, Ian.Campbell@...rix.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] Fix guest memory leak and panic

From: Krishna Kumar <krkumar2@...ibm.com>
Date: Tue, 18 Oct 2011 13:35:23 +0530

> Commit 86ee8130 ("virtionet: convert to SKB paged frag API")
> introduced a bug in guest. During RX testing, guest runs out
> of memory within seconds, causing oom-killer; which then
> panics the system: "Kernel panic - not syncing: Out of memory
> and no killable processes...". /proc/meminfo just before the
> panic shows MemFree is a few MB's:
> 
> 	MemFree:         1928544 kB	(starts here)
> 	...
> 	...
> 	MemFree:           27488 kB
> 	MemFree:           26248 kB
> 	MemFree:           24636 kB
> 	MemFree:           22632 kB
> 	MemFree:           19580 kB
> 	MemFree:           17928 kB
> 	MemFree:           15548 kB
> 		(Panic)
> 
> The extra reference to the fragment pages causes those pages to
> not get freed in skb_release_data(). The following patch fixes
> the bug. I have not checked if any other converted driver has
> the same issue.
> 
> Signed-off-by: Krishna Kumar <krkumar2@...ibm.com>

I'll wait for Ian's full audit, but Krishna please use more appropriate
subject lines in future patch submissions.

This patch is fixing a problem in the virtio_net driver, so please
mention that: "Subject: [PATCH] virtio_net: Fix guest memory leak and panic"
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