linux-kernel - Re: [PATCH v3 3/3] mm/hugetlb: handle races in alloc_huge_page and hugetlb_reserve

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Message-ID: <20150529014946.GB2986@hori1.linux.bs1.fc.nec.co.jp>
Date:	Fri, 29 May 2015 01:49:46 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Mike Kravetz <mike.kravetz@...cle.com>
CC:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	"David Rientjes" <rientjes@...gle.com>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3 3/3] mm/hugetlb: handle races in alloc_huge_page and
 hugetlb_reserve_pages

On Wed, May 27, 2015 at 10:56:11AM -0700, Mike Kravetz wrote:
> alloc_huge_page and hugetlb_reserve_pages use region_chg to
> calculate the number of pages which will be added to the reserve
> map.  Subpool and global reserve counts are adjusted based on
> the output of region_chg.  Before the pages are actually added
> to the reserve map, these routines could race and add fewer
> pages than expected.  If this happens, the subpool and global
> reserve counts are not correct.
> 
> Compare the number of pages actually added (region_add) to those
> expected to added (region_chg).  If fewer pages are actually added,
> this indicates a race and adjust counters accordingly.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>

Reviewed-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>--
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