linux-kernel - Re: [PATCH 1/6] mm/compaction: split freepages without holding the zone lock

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Message-ID: <20160512025123.GB8215@js1304-P5Q-DELUXE>
Date:	Thu, 12 May 2016 11:51:23 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	mgorman@...hsingularity.net, Minchan Kim <minchan@...nel.org>,
	Alexander Potapenko <glider@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH 1/6] mm/compaction: split freepages without holding the
 zone lock

On Tue, May 10, 2016 at 04:56:45PM +0200, Vlastimil Babka wrote:
> On 05/03/2016 07:22 AM, js1304@...il.com wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@....com>
> > 
> > We don't need to split freepages with holding the zone lock. It will cause
> > more contention on zone lock so not desirable.
> 
> Fair enough, I just worry about the same thing as Hugh pointed out
> recently [1] in that it increases the amount of tricky stuff in
> compaction.c doing similar but not quite the same stuff as page/alloc.c,
> and which will be forgotten to be updated once somebody updates
> prep_new_page with e.g. a new debugging check. Can you perhaps think of
> a more robust solution here?

I will try it. I think that factoring some part of prep_new_page() out
would be enough to make thing robust.

Thanks.