From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 5CBC46B012A for ; Wed, 22 Jul 2009 19:08:04 -0400 (EDT) Date: Wed, 22 Jul 2009 16:06:49 -0700 From: Andrew Morton Subject: Re: [PATCH] mm: Warn once when a page is freed with PG_mlocked set V2 Message-Id: <20090722160649.61176c61.akpm@linux-foundation.org> In-Reply-To: References: <20090715125822.GB29749@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: mel@csn.ul.ie, kosaki.motohiro@jp.fujitsu.com, maximlevitsky@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Lee.Schermerhorn@hp.com, penberg@cs.helsinki.fi, hannes@cmpxchg.org, jirislaby@gmail.com List-ID: On Wed, 15 Jul 2009 10:31:54 -0400 (EDT) Christoph Lameter wrote: > On Wed, 15 Jul 2009, Mel Gorman wrote: > > > -static inline int free_pages_check(struct page *page) > > +static inline int free_pages_check(struct page *page, int wasMlocked) > > { > > + WARN_ONCE(wasMlocked, 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); > > + > > if (unlikely(page_mapcount(page) | > > There is already a free_page_mlocked() that is only called if the mlock > bit is set. Move it into there to avoid having to run two checks in the > hot codee path? Agreed. This patch gratuitously adds hotpath overhead. Moving the change to be inside those preexisting wasMlocked tests will reduce its overhead a lot. As it stands, I'm really doubting that the patch's utility is worth its cost. Also, it's a bit of a figleaf, but please consider making more use of CONFIG_DEBUG_VM (see VM_BUG_ON()). -- 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