Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755694Ab0LHAmh (ORCPT ); Tue, 7 Dec 2010 19:42:37 -0500 Received: from kroah.org ([198.145.64.141]:54716 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754829Ab0LHAeV (ORCPT ); Tue, 7 Dec 2010 19:34:21 -0500 X-Mailbox-Line: From gregkh@clark.site Tue Dec 7 16:06:40 2010 Message-Id: <20101208000640.317555522@clark.site> User-Agent: quilt/0.48-11.2 Date: Tue, 07 Dec 2010 16:04:07 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, KAMEZAWA Hiroyuki , Wu Fengguang , Michal Hocko , Mel Gorman Subject: [08/44] mm: fix is_mem_section_removable() page_order BUG_ON check In-Reply-To: <20101208003205.GA4286@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1806 Lines: 57 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: KAMEZAWA Hiroyuki commit 572438f9b52236bd8938b1647cc15e027d27ef55 upstream. page_order() is called by memory hotplug's user interface to check the section is removable or not. (is_mem_section_removable()) It calls page_order() withoug holding zone->lock. So, even if the caller does if (PageBuddy(page)) ret = page_order(page) ... The caller may hit BUG_ON(). For fixing this, there are 2 choices. 1. add zone->lock. 2. remove BUG_ON(). is_mem_section_removable() is used for some "advice" and doesn't need to be 100% accurate. This is_removable() can be called via user program.. We don't want to take this important lock for long by user's request. So, this patch removes BUG_ON(). Signed-off-by: KAMEZAWA Hiroyuki Acked-by: Wu Fengguang Acked-by: Michal Hocko Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/internal.h +++ b/mm/internal.h @@ -49,7 +49,7 @@ extern void __free_pages_bootmem(struct */ static inline unsigned long page_order(struct page *page) { - VM_BUG_ON(!PageBuddy(page)); + /* PageBuddy() must be checked by the caller */ return page_private(page); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/