From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linux-foundation.org (smtp1.linux-foundation.org [140.211.169.13]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "smtp.linux-foundation.org", Issuer "CA Cert Signing Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id E8215B7B77 for ; Fri, 9 Oct 2009 10:35:35 +1100 (EST) Date: Thu, 8 Oct 2009 16:34:49 -0700 From: Andrew Morton To: Robert Jennings Subject: Re: [PATCH 1/2][v2] mm: add notifier in pageblock isolation for balloon drivers Message-Id: <20091008163449.00dce972.akpm@linux-foundation.org> In-Reply-To: <20091002184458.GC4908@austin.ibm.com> References: <20091002184458.GC4908@austin.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linux-mm@kvack.org, Mel Gorman , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Martin Schwidefsky , Badari Pulavarty , Brian King , Paul Mackerras , Ingo Molnar , KAMEZAWA Hiroyuki List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2 Oct 2009 13:44:58 -0500 Robert Jennings wrote: > Memory balloon drivers can allocate a large amount of memory which > is not movable but could be freed to accomodate memory hotplug remove. > > Prior to calling the memory hotplug notifier chain the memory in the > pageblock is isolated. If the migrate type is not MIGRATE_MOVABLE the > isolation will not proceed, causing the memory removal for that page > range to fail. > > Rather than failing pageblock isolation if the the migrateteype is not > MIGRATE_MOVABLE, this patch checks if all of the pages in the pageblock > are owned by a registered balloon driver (or other entity) using a > notifier chain. If all of the non-movable pages are owned by a balloon, > they can be freed later through the memory notifier chain and the range > can still be isolated in set_migratetype_isolate(). The patch looks sane enough to me. I expect that if the powerpc and s390 guys want to work on CMM over the next couple of months, they'd like this patch merged into 2.6.32. It's a bit larger and more involved than one would like, but I guess we can do that if suitable people (Mel? Kamezawa?) have had a close look and are OK with it. What do people think? Has it been carefully compile- and run-time tested with CONFIG_MEMORY_HOTPLUG_SPARSE=n?