linux-kernel - Re: [PATCH] mm: page_alloc: Avoid marking zones full prematurely after zone

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:	Thu, 21 Mar 2013 09:19:02 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Simon Jeons <simon.jeons@...il.com>
Cc:	Mel Gorman <mgorman@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hedi Berriche <hedi@....com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: page_alloc: Avoid marking zones full prematurely
 after zone_reclaim()

On Thu 21-03-13 10:33:07, Simon Jeons wrote:
> Hi Mel,
> On 03/21/2013 02:19 AM, Mel Gorman wrote:
> >The following problem was reported against a distribution kernel when
> >zone_reclaim was enabled but the same problem applies to the mainline
> >kernel. The reproduction case was as follows
> >
> >1. Run numactl -m +0 dd if=largefile of=/dev/null
> >    This allocates a large number of clean pages in node 0
> 
> I confuse why this need allocate a large number of clean pages?

It reads from file and puts pages into the page cache. The pages are not
modified so they are clean. Output file is /dev/null so no pages are
written. dd doesn't call fadvise(POSIX_FADV_DONTNEED) on the input file
by default so pages from the file stay in the page cache
-- 
Michal Hocko
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/