Re: [PATCH 1/9] mm, hugetlb: move up the code which check availability of free huge page

Joonsoo Kim
2013-07-16T01:16:10Z

On Mon, Jul 15, 2013 at 07:31:33PM +0530, Aneesh Kumar K.V wrote:
> Joonsoo Kim <iamjoonsoo.kim@lge.com> writes:
>
> > We don't need to proceede the processing if we don't have any usable
> > free huge page. So move this code up.
>
> I guess you can also mention that since we are holding hugetlb_lock
> hstate values can't change.

Okay. I will mention this for v2.

>
>
> Also.
>
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index e2bfbf7..d87f70b 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -539,10 +539,6 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
> > struct zoneref *z;
> > unsigned int cpuset_mems_cookie;
> >
> > -retry_cpuset:
> > - cpuset_mems_cookie = get_mems_allowed();
> > - zonelist = huge_zonelist(vma, address,
> > - htlb_alloc_mask, &mpol, &nodemask);
> > /*
> > * A child process with MAP_PRIVATE mappings created by their parent
> > * have no page reserves. This check ensures that reservations are
> > @@ -550,11 +546,16 @@ retry_cpuset:
> > */
> > if (!vma_has_reserves(vma) &&
> > h->free_huge_pages - h->resv_huge_pages == 0)
> > - goto err;
> > + return NULL;
> >
>
> If you don't do the above change, the patch will be much simpler.

The patch will be, but output code will not.
With this change, we can remove one goto label('err:') and
this makes code more readable.

Thanks.

>
>
> > /* If reserves cannot be used, ensure enough pages are in the pool */
> > if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
> > - goto err;
> > + return NULL;
> > +
>
> Same here.
>
> > +retry_cpuset:
> > + cpuset_mems_cookie = get_mems_allowed();
> > + zonelist = huge_zonelist(vma, address,
> > + htlb_alloc_mask, &mpol, &nodemask);
> >
> > for_each_zone_zonelist_nodemask(zone, z, zonelist,
> > MAX_NR_ZONES - 1, nodemask) {
> > @@ -572,10 +573,6 @@ retry_cpuset:
> > if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> > goto retry_cpuset;
> > return page;
> > -
> > -err:
> > - mpol_cond_put(mpol);
> > - return NULL;
> > }
> >
> > static void update_and_free_page(struct hstate *h, struct page *page)
>
> -aneesh
>
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