linux-kernel - Re: [RFC PATCH 1/3] mm, numa: rework do_pages

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Message-ID: <20171215095751.GW16951@dhcp22.suse.cz>
Date:   Fri, 15 Dec 2017 10:57:51 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     linux-mm@...ck.org, Zi Yan <zi.yan@...rutgers.edu>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Reale <ar@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/3] mm, numa: rework do_pages_move

On Fri 15-12-17 12:51:25, Kirill A. Shutemov wrote:
> On Fri, Dec 15, 2017 at 10:28:59AM +0100, Michal Hocko wrote:
> > On Thu 14-12-17 18:35:58, Kirill A. Shutemov wrote:
> > > On Wed, Dec 13, 2017 at 03:39:48PM +0100, Michal Hocko wrote:
> > [...]
> > > > +	err = 0;
> > > > +	if (page_to_nid(page) == node)
> > > > +		goto out_putpage;
> > > > +
> > > > +	err = -EACCES;
> > > > +	if (page_mapcount(page) > 1 &&
> > > > +			!migrate_all)
> > > 
> > > Non-sensible line break.
> > 
> > fixed
> > 
> > > > +		goto out_putpage;
> > > > +
> > > > +	if (PageHuge(page)) {
> > > > +		if (PageHead(page)) {
> > > > +			isolate_huge_page(page, pagelist);
> > > > +			err = 0;
> > > > +		}
> > > > +	} else {
> > > 
> > > Hm. I think if the page is PageTail() we have to split the huge page.
> > > If an user asks to migrate part of THP, we shouldn't migrate the whole page,
> > > otherwise it's not transparent anymore.
> > 
> > Well, as I've said in the cover letter. There are more things which are
> > worth considering but I've tried to keep the original semantic so
> > further changes should be done in separete patches. I will work on those
> > but I would prefer this to stay smaller if you do not mind.
> 
> Sure.
> 
> Fill free to use my ack.

Thanks a lot Kirill! I will wait for some more feedback and then
resubmit later next week.

-- 
Michal Hocko
SUSE Labs