linux-kernel - Re: question on NUMA page migration

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: <1350669236.2768.66.camel@twins>
Date:	Fri, 19 Oct 2012 19:53:56 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Rik van Riel <riel@...hat.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Mel Gorman <mel@....ul.ie>,
	Linux kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: question on NUMA page migration

On Fri, 2012-10-19 at 13:13 -0400, Rik van Riel wrote:

> Would it make sense to have the normal page migration code always
> work with the extra refcount, so we do not have to introduce a new
> MIGRATE_FAULT migration mode?
> 
> On the other hand, compaction does not take the extra reference...

Right, it appears to not do this, it gets pages from the pfn and
zone->lock and the isolate_lru_page() call is the first reference.

> Another alternative might be to do the put_page inside
> do_prot_none_numa().  That would be analogous to do_wp_page
> disposing of the old page for the caller.

It'd have to be inside migrate_misplaced_page(), can't do before
isolate_lru_page() or the page might disappear. Doing it after is
(obviously) too late.

> I am not real happy about NUMA migration introducing its own
> migration mode...

You didn't seem to mind too much earlier, but I can remove it if you
want.
--
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/