linux-kernel - Re: [PATCH 16/27] mm: Move page mapped accounting to the node

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: <20160623083500.GO1868@techsingularity.net>
Date:	Thu, 23 Jun 2016 09:35:01 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linux-MM <linux-mm@...ck.org>, Rik van Riel <riel@...riel.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 16/27] mm: Move page mapped accounting to the node

On Tue, Jun 21, 2016 at 03:32:06PM -0700, Andrew Morton wrote:
> On Tue, 21 Jun 2016 15:15:55 +0100 Mel Gorman <mgorman@...hsingularity.net> wrote:
> 
> > Reclaim makes decisions based on the number of pages that are mapped
> > but it's mixing node and zone information. Account NR_FILE_MAPPED and
> > NR_ANON_PAGES pages on the node.
> 
> <wading through rejects>
> 
> Boy, the difference between
> 
> 	__mod_zone_page_state(page_zone(page), ...
> 
> and
> 
> 	__mod_node_page_state(page_pgdat(page), ...
> 
> is looking subtle.  When and why to use one versus the other.  I'm not
> seeing any explanation of this in there but haven't yet looked hard.
> 

I'm not sure I see the problem. One applies for zone stats and the other
is for node. Granted, care is needed to use the correct one or a random
stat is updated instead of the one intended.


-- 
Mel Gorman
SUSE Labs