linux-kernel - Re: [PATCH 08/18] mm, hugetlb: do hugepage_subpool_get_pages() when avoid

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Date:	Wed, 31 Jul 2013 14:02:50 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	David Gibson <david@...son.dropbear.id.au>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Hillf Danton <dhillf@...il.com>
Subject: Re: [PATCH 08/18] mm, hugetlb: do hugepage_subpool_get_pages() when
 avoid_reserve

On Mon, Jul 29, 2013 at 02:05:51PM -0400, Naoya Horiguchi wrote:
> On Mon, Jul 29, 2013 at 02:31:59PM +0900, Joonsoo Kim wrote:
> > When we try to get a huge page with avoid_reserve, we don't consume
> > a reserved page. So it is treated like as non-reserve case.
> 
> This patch will be completely overwritten with 9/18.
> So is this patch necessary?

Yes. This is a bug fix, so should be separate.
When we try to allocate with avoid_reserve, we don't use reserved page pool.
So, hugepage_subpool_get_pages() should be called and returned if failed.

If we merge these into one, we cannot know that there exists a bug.

Thanks.

> 
> Naoya Horiguchi
> 
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> > 
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 1426c03..749629e 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1149,12 +1149,13 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> >  	if (has_reserve < 0)
> >  		return ERR_PTR(-ENOMEM);
> >  
> > -	if (!has_reserve && (hugepage_subpool_get_pages(spool, 1) < 0))
> > +	if ((!has_reserve || avoid_reserve)
> > +		&& (hugepage_subpool_get_pages(spool, 1) < 0))
> >  			return ERR_PTR(-ENOSPC);
> >  
> >  	ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
> >  	if (ret) {
> > -		if (!has_reserve)
> > +		if (!has_reserve || avoid_reserve)
> >  			hugepage_subpool_put_pages(spool, 1);
> >  		return ERR_PTR(-ENOSPC);
> >  	}
> > @@ -1167,7 +1168,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> >  			hugetlb_cgroup_uncharge_cgroup(idx,
> >  						       pages_per_huge_page(h),
> >  						       h_cg);
> > -			if (!has_reserve)
> > +			if (!has_reserve || avoid_reserve)
> >  				hugepage_subpool_put_pages(spool, 1);
> >  			return ERR_PTR(-ENOSPC);
> >  		}
> > -- 
> > 1.7.9.5
> >
> 
> --
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