From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755407Ab1ABH6y (ORCPT ); Sun, 2 Jan 2011 02:58:54 -0500 Received: from mail.windriver.com ([147.11.1.11]:35248 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753536Ab1ABHXC (ORCPT ); Sun, 2 Jan 2011 02:23:02 -0500 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, KAMEZAWA Hiroyuki , Michal Hocko , Wu Fengguang , Mel Gorman , Andrew Morton , Linus Torvalds , Paul Gortmaker Subject: [34-longterm 073/260] memory hotplug: fix next block calculation in is_removable Date: Sun, 2 Jan 2011 02:16:09 -0500 Message-Id: <1293952756-15010-74-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.3.3 In-Reply-To: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> References: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> X-OriginalArrivalTime: 02 Jan 2011 07:21:27.0398 (UTC) FILETIME=[AB56B060:01CBAA4D] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: KAMEZAWA Hiroyuki commit 0dcc48c15f63ee86c2fcd33968b08d651f0360a5 upstream. 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 Cc: Michal Hocko Cc: Wu Fengguang Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Paul Gortmaker --- mm/memory_hotplug.c | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index be211a5..91f7c26 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -558,19 +558,19 @@ static inline int pageblock_free(struct page *page) /* 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 < MAX_ORDER) && (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. */ -- 1.7.3.3