linux-kernel - Re: [RFC 03/13] mm, page_alloc: don't retry initial attempt 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:	Tue, 31 May 2016 14:03:51 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	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>
Subject: Re: [RFC 03/13] mm, page_alloc: don't retry initial attempt in
 slowpath

On 05/31/2016 08:25 AM, Joonsoo Kim wrote:
> On Tue, May 10, 2016 at 09:35:53AM +0200, Vlastimil Babka wrote:
>> After __alloc_pages_slowpath() sets up new alloc_flags and wakes up kswapd, it
>> first tries get_page_from_freelist() with the new alloc_flags, as it may
>> succeed e.g. due to using min watermark instead of low watermark. This attempt
>> does not have to be retried on each loop, since direct reclaim, direct
>> compaction and oom call get_page_from_freelist() themselves.
>
> Hmm... there is a corner case. If did_some_progress is 0 or compaction
> is deferred, get_page_from_freelist() isn't called. But, we can
> succeed to allocate memory since there is a kswapd that reclaims
> memory in background.

Hmm good point. I think the cleanest solution is to let 
__alloc_pages_direct_reclaim attempt regardless of did_some_progress.

> Thanks.
>