Re: [PATCH -mm] vmscan: report vm_flags in page_referenced()

Wu Fengguang
2009-05-12T11:45:23Z

On Tue, May 12, 2009 at 02:44:13PM +0800, Minchan Kim wrote:
> On Tue, 12 May 2009 08:23:09 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > On Tue, 2009-05-12 at 10:51 +0800, Wu Fengguang wrote:
> > > @@ -406,6 +408,7 @@ static int page_referenced_anon(struct p
> > > if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
> > > continue;
> > > referenced += page_referenced_one(page, vma, &mapcount);
> > > + *vm_flags |= vma->vm_flags;
> > > if (!mapcount)
> > > break;
> > > }
> >
> > Shouldn't that read:
> >
> > if (page_referenced_on(page, vma, &mapcount)) {
> > referenced++;
> > *vm_flags |= vma->vm_flags;
> > }
> >
> > So that we only add the vma-flags of those vmas that actually have a
> > young bit set?
> >
> > In which case it'd be more at home in page_referenced_one():
> >
> > @@ -381,6 +381,8 @@ out_unmap:
> > (*mapcount)--;
> > pte_unmap_unlock(pte, ptl);
> > out:
> > + if (referenced)
> > + *vm_flags |= vma->vm_flags;
> > return referenced;
> > }
>
> Good. I am ACK for peter's suggestion.
> It can prevent setting vm_flag for worng vma which don't have the page.

Good suggestions! I realized now it is a flaky idea to not do that in
page_referenced_one(), hehe.

Thanks,
Fengguang