Re: Page allocation failures in guest

From: Avi Kivity
Date: Tue Aug 11 2009 - 07:51:52 EST


On 08/11/2009 09:32 AM, Pierre Ossman wrote:
On Mon, 13 Jul 2009 23:59:52 +0900
Minchan Kim<minchan.kim@xxxxxxxxx> wrote:

On Mon, Jul 13, 2009 at 6:51 PM, Pierre Ossman<drzeus-list@xxxxxxxxx> wrote:
Jul 12 23:04:54 loki kernel: Active_anon:14065 active_file:87384 inactive_anon:37480
Jul 12 23:04:54 loki kernel: inactive_file:95821 unevictable:4 dirty:8 writeback:0 unstable:0
Jul 12 23:04:54 loki kernel: free:1344 slab:7113 mapped:4283 pagetables:5656 bounce:0
Jul 12 23:04:54 loki kernel: Node 0 DMA free:3988kB min:24kB low:28kB high:36kB active_anon:0kB inactive_anon:0kB active_file:3532kB inactive_file:1032kB unevictable:0kB present:6840kB pages_scanned:0 all_un
I don't know why present is bigger than free + [in]active anon ?
Who know this ?

There are 258 pages in inactive file.
Unfortunately, it seems we don't have any discardable pages.
The reclaimer can't sync dirty pages to reclaim them, too.
That's because we are going on GFP_ATOMIC as I mentioned.


Any ideas here? Is the virtio net driver very GFP_ATOMIC happy so it
drains all those pages? And why is this triggered by a kernel upgrade
in the host?

Avi?


Rusty?

reclaimable? no
Jul 12 23:04:54 loki kernel: lowmem_reserve[]: 0 994 994 994
Jul 12 23:04:54 loki kernel: Node 0 DMA32 free:1388kB min:4020kB low:5024kB high:6028kB active_anon:56260kB inactive_anon:149920kB active_file:346004kB inactive_file:382252kB unevictable:16kB present:1018016
free : 1388KB min : 4020KB. In addtion, now GFP_HIGH. so calculation
is as follow for zone_watermark_ok.

1388< (4020 / 2)

So failed it in zone_watermark_ok.
AFAIU, it's fairy OOM problem.


I doesn't get out of it though, or at least the virtio net driver
wedges itself.

Rgds


--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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