Re: [PATCH] Fix guest memory leak and panic

[David Miller <davem@davemloft.net>]

From: Krishna Kumar <krkumar2@in.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@in.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"