Message-ID: <1391023456.18140.8.camel@buesod1.americas.hpqcorp.net>
Subject: Re: [PATCH 6/8] mm, hugetlb: remove vma_has_reserves
From: Davidlohr Bueso <davidlohr@hp.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, riel@redhat.com,
        mgorman@suse.de, mhocko@suse.cz, aneesh.kumar@linux.vnet.ibm.com,
        kamezawa.hiroyu@jp.fujitsu.com, hughd@google.com,
        david@gibson.dropbear.id.au, js1304@gmail.com,
        liwanp@linux.vnet.ibm.com, dhillf@gmail.com, rientjes@google.com,
        aswin@hp.com, scott.norton@hp.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Date: Wed, 29 Jan 2014 11:24:16 -0800
In-Reply-To: <1390856653-v1nkcg1e-mutt-n-horiguchi@ah.jp.nec.com>
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	 <1390794746-16755-7-git-send-email-davidlohr@hp.com>
	 <1390856653-v1nkcg1e-mutt-n-horiguchi@ah.jp.nec.com>
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On Mon, 2014-01-27 at 16:04 -0500, Naoya Horiguchi wrote:
> On Sun, Jan 26, 2014 at 07:52:24PM -0800, Davidlohr Bueso wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > 
> > vma_has_reserves() can be substituted by using return value of
> > vma_needs_reservation(). If chg returned by vma_needs_reservation()
> > is 0, it means that vma has reserves. Otherwise, it means that vma don't
> > have reserves and need a hugepage outside of reserve pool. This definition
> > is perfectly same as vma_has_reserves(), so remove vma_has_reserves().
> 
> I'm concerned that this patch doesn't work when VM_NORESERVE is set.
> vma_needs_reservation() doesn't check VM_NORESERVE and this patch changes
> dequeue_huge_page_vma() not to check it. So no one seems to check it any more.

Good catch. I agree, this is new behavior and quite frankly not worth
changing just for a cleanup - the code is subtle enough as it is. I'm
dropping this patch and #7 which depends on this one, if Joonsoo wants
to later pursue this, he can.

Thanks,
Davidlohr

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