linux-kernel - Re: [PATCH 8/8] Per-container pages reclamation

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Message-Id: <20070531105842.0728f577.akpm@linux-foundation.org>
Date:	Thu, 31 May 2007 10:58:42 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Pavel Emelianov <xemul@...nvz.org>
Cc:	Balbir Singh <balbir@...ibm.com>, Paul Menage <menage@...gle.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	devel@...nvz.org, Kirill Korotaev <dev@...nvz.org>
Subject: Re: [PATCH 8/8] Per-container pages reclamation

On Thu, 31 May 2007 14:35:43 +0400
Pavel Emelianov <xemul@...nvz.org> wrote:

> > Would I be correct in guessing that pages which are on the
> > per-rss-container lists are also eligible for reclaim off the traditional
> > page LRUs?  If so, how does that work?  When a page gets freed off the
> 
> Yes. All the pages are accessible from booth - global and per-container
> LRU lists and reclamation can be performed from booth.
> 
> > per-zone LRUs does it also get removed from the per-rss_container LRU?  But
> > how can this be right?  
> 
> I don't get your idea here.

If we have a page which is on the zone LRU with refcount=1 and someone does
put_page() on it, we will take that page off the zone LRU and then actually
free the page.

I am assuming that your patches change that logic so that we will also
remove that page from the per-container LRU at the same time?

If so, the problem which I see is that, under rare circumstances, that
final put_page() will occur from interrupt context.  Hence we would be
trying to remove the page from the per-container LRU at interrupt time. 
But the locks which you have in there are not suited for taking from
interrupt context.

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