linux-kernel - Re: [patch v2 2/4] mm, compaction: return failed migration target pages back to freelist

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140502101109.GP23991@suse.de>
Date:	Fri, 2 May 2014 11:11:09 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Greg Thelen <gthelen@...gle.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [patch v2 2/4] mm, compaction: return failed migration target
 pages back to freelist

On Thu, May 01, 2014 at 02:35:42PM -0700, David Rientjes wrote:
> Memory compaction works by having a "freeing scanner" scan from one end of a 
> zone which isolates pages as migration targets while another "migrating scanner" 
> scans from the other end of the same zone which isolates pages for migration.
> 
> When page migration fails for an isolated page, the target page is returned to 
> the system rather than the freelist built by the freeing scanner.  This may 
> require the freeing scanner to continue scanning memory after suitable migration 
> targets have already been returned to the system needlessly.
> 
> This patch returns destination pages to the freeing scanner freelist when page 
> migration fails.  This prevents unnecessary work done by the freeing scanner but 
> also encourages memory to be as compacted as possible at the end of the zone.
> 
> Reported-by: Greg Thelen <gthelen@...gle.com>
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Acked-by: Mel Gorman <mgorman@...e.de>

-- 
Mel Gorman
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/