Re: Page scan keeps touching kernel text pages

From: JÃrn Engel
Date: Mon Feb 25 2008 - 12:36:43 EST


On Mon, 25 February 2008 16:15:36 +0100, JÃrn Engel wrote:
> On Mon, 25 February 2008 15:07:24 +0000, Andy Whitcroft wrote:
>
> > I would expect to find pages below the kernel text as real pages, and
> > potentially on the LRU on some architectures. Which architecture are
> > you seeing this? Which zones do the pages belong?
>
> 32bit x86 (run in qemu, shouldn't make a difference).
>
> Not sure about the zones. Let me rerun to check that.

Example output:
scanning zone DMA
page 3fa 3 00000000 628
page 2bf 2 00000000 628
page 97 3 00000000 628
page 98 2 00000000 628
scanning zone DMA
page 2c0 3 00000000 628
page 2c3 2 00000000 628
page 44 3 00000000 628
page 46 2 00000000 628
scanning zone DMA
page 37 3 00000000 628
page 35 2 00000000 628
page 32 3 00000000 628
page 38 2 00000000 628

Looks like all kernel text is in zone DMA. Second column holds the page
number, third is refcount, fourth is the flags, fifth is the line, which
corresponds to this one after my debugging changes:
if (!mapping || !remove_mapping(mapping, page))
goto keep_locked;

JÃrn

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