linux-kernel - Re: [PATCH 1/8] mm, compaction: don't isolate PageWriteback pages in MIGRATE_SYNC

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Date:	Tue, 19 Jul 2016 15:21:20 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Vlastimil Babka <vbabka@...e.cz>
cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...nel.org>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH 1/8] mm, compaction: don't isolate PageWriteback pages
 in MIGRATE_SYNC_LIGHT mode

On Mon, 18 Jul 2016, Vlastimil Babka wrote:

> From: Hugh Dickins <hughd@...gle.com>
> 
> At present MIGRATE_SYNC_LIGHT is allowing __isolate_lru_page() to
> isolate a PageWriteback page, which __unmap_and_move() then rejects
> with -EBUSY: of course the writeback might complete in between, but
> that's not what we usually expect, so probably better not to isolate it.
> 
> When tested by stress-highalloc from mmtests, this has reduced the number of
> page migrate failures by 60-70%.
> 
> Signed-off-by: Hugh Dickins <hughd@...gle.com>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> Acked-by: Michal Hocko <mhocko@...e.com>

Acked-by: David Rientjes <rientjes@...gle.com>