linux-kernel - Re: [PATCH] NOMMU: Separate out VMAs

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Date:	Tue, 07 Aug 2007 15:12:33 +0200
From:	Bernd Schmidt <bernds_cb1@...nline.de>
To:	David Howells <dhowells@...hat.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Wu, Bryan" <Bryan.Wu@...log.com>
Subject: Re: [PATCH] NOMMU: Separate out VMAs

David Howells wrote:
> Here's a preview of my patch to give each process a separate list of VMAs
> under NOMMU mode, just as under MMU mode.  Could you have a look over it
> please?

I've managed to apply it to our Blackfin tree and started looking at it.

> Could you also see if you get a memory leak on the blackfin CPU?  I see a leak
> when I use this patch, but I'm not sure whether it's this patch, or whether
> it's something else in the arch that is suppressed without this patch.
> 
> As far as I can tell by page counting there shouldn't be a leak.

There is a leak:

root:~> while true; do
> cat /proc/buddyinfo
> sleep 1
> done
Node 0, zone      DMA     20      1      1      1      0      1      1
    1      0      0      0      1      2      0
Node 0, zone      DMA     32      1      1      0      0      0      1
    0      0      0      0      1      2      0
Node 0, zone      DMA     47      1      1      1      1      0      0
    1      1      1      1      0      2      0
Node 0, zone      DMA     62      1      1      0      1      1      1
    1      0      1      1      0      2      0
Node 0, zone      DMA     77      1      1      1      0      0      1
    0      0      1      1      0      2      0
Node 0, zone      DMA     92      1      1      0      0      1      0
    1      1      0      1      0      2      0
Node 0, zone      DMA    107      1      1      1      1      1      1
    1      0      0      1      0      2      0
Node 0, zone      DMA    122      1      1      0      1      0      1
    0      0      0      1      0      2      0
Node 0, zone      DMA    137      1      1      1      0      1      0
    1      1      1      0      0      2      0
... and so on.  It's a strange pattern of fragmentation, as if it keeps
allocating 8k pages and freeing one half of them.

Will play with this some more.  Thanks!


Bernd
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