Re: new procfs memory analysis feature

[david singleton]

On Dec 7, 2006, at 5:46 PM, Andrew Morton wrote:

> On Thu, 7 Dec 2006 17:07:22 -0800
> david singleton <dsingleton@xxxxxxxxxx> wrote:
>
> > Attached is the 2.6.19 patch.
>
> It still has the overflow bug.
> > +       do {
> > +               ptent = *pte;
> > +               if (pte_present(ptent)) {
> > +                       page = vm_normal_page(vma, addr, ptent);
> > +                       if (page) {
> > +                               if (pte_dirty(ptent))
> > +                                       mapcount = 
> > -page_mapcount(page);
> > +                               else
> > +                                       mapcount = 
> > page_mapcount(page);
> > +                       } else {
> > +                               mapcount = 1;
> > +                       }
> > +               }
> > +               seq_printf(m, " %d", mapcount);
> > +
> > +       } while (pte++, addr += PAGE_SIZE, addr != end);
>
> Well that's cute.  As long as both seq_file and pte-pages are of size
> PAGE_SIZE, and as long as pte's are more than three bytes, this will 
> not
> overflow the seq_file output buffer.
>
> hm.  Unless the pages are all dirty and the mapcounts are all 10000.  I
> think it will overflow then?

I guess that could happen?    Any suggestions?

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