From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754386Ab0IAMlp (ORCPT ); Wed, 1 Sep 2010 08:41:45 -0400 Received: from cantor2.suse.de ([195.135.220.15]:46551 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752404Ab0IAMlo (ORCPT ); Wed, 1 Sep 2010 08:41:44 -0400 Date: Wed, 1 Sep 2010 14:41:38 +0200 From: Michal Hocko To: Wu Fengguang Cc: "linux-mm@kvack.org" , Andrew Morton , "Kleen, Andi" , Haicheng Li , Christoph Lameter , "linux-kernel@vger.kernel.org" , Mel Gorman Subject: Re: [PATCH] Make is_mem_section_removable more conformable with offlining code Message-ID: <20100901124138.GD6663@tiehlicka.suse.cz> References: <20100820141400.GD4636@tiehlicka.suse.cz> <20100822004232.GA11007@localhost> <20100823092246.GA25772@tiehlicka.suse.cz> <20100831141942.GA30353@localhost> <20100901121951.GC6663@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100901121951.GC6663@tiehlicka.suse.cz> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 01-09-10 14:19:51, Michal Hocko wrote: > On Tue 31-08-10 22:19:42, Wu Fengguang wrote: > > On Mon, Aug 23, 2010 at 05:22:46PM +0800, Michal Hocko wrote: > > > On Sun 22-08-10 08:42:32, Wu Fengguang wrote: > > > > Hi Michal, > > > > > > Hi, > > > > > > > > > > > It helps to explain in changelog/code > > > > > > > > - in what situation a ZONE_MOVABLE will contain !MIGRATE_MOVABLE > > > > pages? > > > > > > page can be MIGRATE_RESERVE IIUC. > > > > Yup, it may also be set to MIGRATE_ISOLATE by soft_offline_page(). > > Doesn't it make sense to check for !MIGRATE_UNMOVABLE then? Something like the following patch. >>From de85f1aa42115678d3340f0448cd798577036496 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 20 Aug 2010 15:39:16 +0200 Subject: [PATCH] Make is_mem_section_removable more conformable with offlining code Currently is_mem_section_removable checks whether each pageblock from the given pfn range is of MIGRATE_MOVABLE type or if it is free. If both are false then the range is considered non removable. On the other hand, offlining code (more specifically set_migratetype_isolate) doesn't care whether a page is free and instead it just checks the migrate type of the page and whether the page's zone is movable. This can lead into a situation when we can mark a node as not removable just because a pageblock is MIGRATE_RESERVE and it is not free. Let's make a common helper is_page_removable which unifies both tests at one place. Also let's check for MIGRATE_UNMOVABLE rather than all possible MIGRATEable types. Signed-off-by: Michal Hocko --- include/linux/mmzone.h | 26 ++++++++++++++++++++++++++ mm/memory_hotplug.c | 19 +------------------ mm/page_alloc.c | 5 +---- 3 files changed, 28 insertions(+), 22 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6e6e626..7aaa272 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -669,6 +669,32 @@ unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long); */ #define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones) +#ifdef CONFIG_MEMORY_HOTREMOVE +/* + * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy + * set and the size of the free page is given by page_order(). Using this, + * the function determines if the pageblock contains only free pages. + * Due to buddy contraints, a free page at least the size of a pageblock will + * be located at the start of the pageblock + */ +static inline int pageblock_free(struct page *page) +{ + return PageBuddy(page) && page_order(page) >= pageblock_order; +} + +/* + * A free pageblock or the one which is movable or reclaimable is + * considered to be removable + */ +static inline bool is_page_removable(struct page *page) +{ + return get_pageblock_migratetype(page) != MIGRATE_UNMOVABLE + || pageblock_free(page); +} +#else +#define is_page_removable(p) 0 +#endif + static inline int populated_zone(struct zone *zone) { return (!!zone->present_pages); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index a4cfcdc..66195b8 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -569,17 +569,6 @@ out: EXPORT_SYMBOL_GPL(add_memory); #ifdef CONFIG_MEMORY_HOTREMOVE -/* - * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy - * set and the size of the free page is given by page_order(). Using this, - * the function determines if the pageblock contains only free pages. - * Due to buddy contraints, a free page at least the size of a pageblock will - * be located at the start of the pageblock - */ -static inline int pageblock_free(struct page *page) -{ - return PageBuddy(page) && page_order(page) >= pageblock_order; -} /* Return the start of the next active pageblock after a given page */ static struct page *next_active_pageblock(struct page *page) @@ -608,13 +597,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages) /* Check the starting page of each pageblock within the range */ for (; page < end_page; page = next_active_pageblock(page)) { - type = get_pageblock_migratetype(page); - - /* - * A pageblock containing MOVABLE or free pages is considered - * removable - */ - if (type != MIGRATE_MOVABLE && !pageblock_free(page)) + if (!is_page_removable(page)) return 0; /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a9649f4..c2e2576 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5277,14 +5277,11 @@ int set_migratetype_isolate(struct page *page) struct memory_isolate_notify arg; int notifier_ret; int ret = -EBUSY; - int zone_idx; zone = page_zone(page); - zone_idx = zone_idx(zone); spin_lock_irqsave(&zone->lock, flags); - if (get_pageblock_migratetype(page) == MIGRATE_MOVABLE || - zone_idx == ZONE_MOVABLE) { + if (is_page_removable(page)) { ret = 0; goto out; } -- 1.7.1 -- Michal Hocko L3 team SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id C570D6B0047 for ; Wed, 1 Sep 2010 08:41:45 -0400 (EDT) Date: Wed, 1 Sep 2010 14:41:38 +0200 From: Michal Hocko Subject: Re: [PATCH] Make is_mem_section_removable more conformable with offlining code Message-ID: <20100901124138.GD6663@tiehlicka.suse.cz> References: <20100820141400.GD4636@tiehlicka.suse.cz> <20100822004232.GA11007@localhost> <20100823092246.GA25772@tiehlicka.suse.cz> <20100831141942.GA30353@localhost> <20100901121951.GC6663@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100901121951.GC6663@tiehlicka.suse.cz> Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: "linux-mm@kvack.org" , Andrew Morton , "Kleen, Andi" , Haicheng Li , Christoph Lameter , "linux-kernel@vger.kernel.org" , Mel Gorman List-ID: On Wed 01-09-10 14:19:51, Michal Hocko wrote: > On Tue 31-08-10 22:19:42, Wu Fengguang wrote: > > On Mon, Aug 23, 2010 at 05:22:46PM +0800, Michal Hocko wrote: > > > On Sun 22-08-10 08:42:32, Wu Fengguang wrote: > > > > Hi Michal, > > > > > > Hi, > > > > > > > > > > > It helps to explain in changelog/code > > > > > > > > - in what situation a ZONE_MOVABLE will contain !MIGRATE_MOVABLE > > > > pages? > > > > > > page can be MIGRATE_RESERVE IIUC. > > > > Yup, it may also be set to MIGRATE_ISOLATE by soft_offline_page(). > > Doesn't it make sense to check for !MIGRATE_UNMOVABLE then? Something like the following patch.