linux-kernel - Re: [RFC 04/13] mm, page_alloc: restructure direct compaction handling in slowpath

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]

Date:	Fri, 13 May 2016 10:31:11 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Johannes Weiner <hannes@...xchg.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [RFC 04/13] mm, page_alloc: restructure direct compaction
 handling in slowpath

On Fri 13-05-16 10:10:50, Vlastimil Babka wrote:
> On 05/12/2016 03:29 PM, Michal Hocko wrote:
> > On Tue 10-05-16 09:35:54, Vlastimil Babka wrote:
> > > This patch attempts to restructure the code with only minimal functional
> > > changes. The call to the first compaction and THP-specific checks are now
> > > placed above the retry loop, and the "noretry" direct compaction is removed.
> > > 
> > > The initial compaction is additionally restricted only to costly orders, as we
> > > can expect smaller orders to be held back by watermarks, and only larger orders
> > > to suffer primarily from fragmentation. This better matches the checks in
> > > reclaim's shrink_zones().
> > > 
> > > There are two other smaller functional changes. One is that the upgrade from
> > > async migration to light sync migration will always occur after the initial
> > > compaction.
> > 
> > I do not think this belongs to the patch. There are two reasons. First
> > we do not need to do potentially more expensive sync mode when async is
> > able to make some progress and the second
> 
> My concern was that __GFP_NORETRY non-costly allocations wouldn't otherwise
> get a MIGRATE_SYNC_LIGHT pass at all. Previously they would get it in the
> noretry: label.

OK, I haven't considered this. So scratch this then.
-- 
Michal Hocko
SUSE Labs