From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754570AbZGOMqJ (ORCPT ); Wed, 15 Jul 2009 08:46:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754145AbZGOMqI (ORCPT ); Wed, 15 Jul 2009 08:46:08 -0400 Received: from cmpxchg.org ([85.214.51.133]:47694 "EHLO cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752645AbZGOMqI (ORCPT ); Wed, 15 Jul 2009 08:46:08 -0400 Date: Wed, 15 Jul 2009 14:45:09 +0200 From: Johannes Weiner To: Mel Gorman Cc: Andrew Morton , kosaki.motohiro@jp.fujitsu.com, Maxim Levitsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lee Schermerhorn , Christoph Lameter , Pekka Enberg , Jiri Slaby Subject: Re: [PATCH] mm: Warn once when a page is freed with PG_mlocked set (resend) Message-ID: <20090715124509.GA1854@cmpxchg.org> References: <20090715104833.GB9267@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090715104833.GB9267@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Mel, On Wed, Jul 15, 2009 at 11:48:34AM +0100, Mel Gorman wrote: > When a page is freed with the PG_mlocked set, it is considered an unexpected > but recoverable situation. A counter records how often this event happens > but it is easy to miss that this event has occured at all. This patch warns > once when PG_mlocked is set to prompt debuggers to check the counter to > see how often it is happening. > > Signed-off-by: Mel Gorman > --- > mm/page_alloc.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index caa9268..f8902e7 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -495,8 +495,16 @@ static inline void free_page_mlock(struct page *page) > static void free_page_mlock(struct page *page) { } > #endif > > -static inline int free_pages_check(struct page *page) > -{ > +static inline int free_pages_check(struct page *page, int wasMlocked) > +{ > + if (unlikely(wasMlocked)) { > + WARN_ONCE(1, KERN_WARNING > + "Page flag mlocked set for process %s at pfn:%05lx\n" > + "page:%p flags:0x%lX\n", > + current->comm, page_to_pfn(page), > + page, page->flags|__PG_MLOCKED); Since the warning is the only action in this branch, wouldn't WARN_ONCE(wasMlocked, KERN_WARNING ...) be better? Hannes