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 CE07A6B004D for ; Thu, 2 Sep 2010 23:17:06 -0400 (EDT) Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o833H4Wl021896 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 3 Sep 2010 12:17:04 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id B20D245DE54 for ; Fri, 3 Sep 2010 12:17:03 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (s5.gw.fujitsu.co.jp [10.0.50.95]) by m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 81D0245DE4F for ; Fri, 3 Sep 2010 12:17:03 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 642951DB8040 for ; Fri, 3 Sep 2010 12:17:03 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 136321DB803F for ; Fri, 3 Sep 2010 12:17:03 +0900 (JST) Date: Fri, 3 Sep 2010 12:11:59 +0900 From: KAMEZAWA Hiroyuki Subject: [PATCH 1/2][BUGFIX] fix next active pageblock calculation Message-Id: <20100903121159.30099a9c.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100903121003.e2b8993a.kamezawa.hiroyu@jp.fujitsu.com> References: <20100901121951.GC6663@tiehlicka.suse.cz> <20100901124138.GD6663@tiehlicka.suse.cz> <20100902144500.a0d05b08.kamezawa.hiroyu@jp.fujitsu.com> <20100902082829.GA10265@tiehlicka.suse.cz> <20100902180343.f4232c6e.kamezawa.hiroyu@jp.fujitsu.com> <20100902092454.GA17971@tiehlicka.suse.cz> <20100902131855.GC10265@tiehlicka.suse.cz> <20100902143939.GD10265@tiehlicka.suse.cz> <20100902150554.GE10265@tiehlicka.suse.cz> <20100903121003.e2b8993a.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Michal Hocko , Hiroyuki Kamezawa , Wu Fengguang , "linux-mm@kvack.org" , Andrew Morton , "Kleen, Andi" , Haicheng Li , Christoph Lameter , "linux-kernel@vger.kernel.org" , Mel Gorman List-ID: From: KAMEZAWA Hiroyuki next_active_pageblock() is for finding next _used_ freeblock. It skips several blocks when it finds there are a chunk of free pages lager than pageblock. But it has 2 bugs. 1. We have no lock. page_order(page) - pageblock_order can be minus. 2. pageblocks_stride += is wrong. it should skip page_order(p) of pages. Signed-off-by: KAMEZAWA Hiroyuki --- mm/memory_hotplug.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) Index: mmotm-0827/mm/memory_hotplug.c =================================================================== --- mmotm-0827.orig/mm/memory_hotplug.c +++ mmotm-0827/mm/memory_hotplug.c @@ -584,19 +584,19 @@ static inline int pageblock_free(struct /* Return the start of the next active pageblock after a given page */ static struct page *next_active_pageblock(struct page *page) { - int pageblocks_stride; - /* Ensure the starting page is pageblock-aligned */ BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1)); - /* Move forward by at least 1 * pageblock_nr_pages */ - pageblocks_stride = 1; - /* If the entire pageblock is free, move to the end of free page */ - if (pageblock_free(page)) - pageblocks_stride += page_order(page) - pageblock_order; + if (pageblock_free(page)) { + int order; + /* be careful. we don't have locks, page_order can be changed.*/ + order = page_order(page); + if (order > pageblock_order) + return page + (1 << order); + } - return page + (pageblocks_stride * pageblock_nr_pages); + return page + pageblock_nr_pages; } /* Checks if this range of memory is likely to be hot-removable. */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org