From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754592AbZGOM4z (ORCPT ); Wed, 15 Jul 2009 08:56:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754468AbZGOM4y (ORCPT ); Wed, 15 Jul 2009 08:56:54 -0400 Received: from gir.skynet.ie ([193.1.99.77]:38665 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753500AbZGOM4x (ORCPT ); Wed, 15 Jul 2009 08:56:53 -0400 Date: Wed, 15 Jul 2009 13:56:52 +0100 From: Mel Gorman To: Johannes Weiner 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: <20090715125652.GA29749@csn.ul.ie> References: <20090715104833.GB9267@csn.ul.ie> <20090715124509.GA1854@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20090715124509.GA1854@cmpxchg.org> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 15, 2009 at 02:45:09PM +0200, Johannes Weiner wrote: > 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? > It was to have the unlikely() but now that I look at WARN_ONCE(), it looks like it does the unlikely() part already. Will send another version. Thanks -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab