From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757120AbZFQQxU (ORCPT ); Wed, 17 Jun 2009 12:53:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752830AbZFQQxM (ORCPT ); Wed, 17 Jun 2009 12:53:12 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:38970 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752098AbZFQQxM (ORCPT ); Wed, 17 Jun 2009 12:53:12 -0400 Date: Wed, 17 Jun 2009 18:52:56 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Andrew Morton , Mel Gorman , Catalin Marinas , fengguang.wu@intel.com, Pekka Enberg , linux-kernel@vger.kernel.org Subject: Re: WARNING: at mm/page_alloc.c:1159 get_page_from_freelist+0x325/0x655() Message-ID: <20090617165256.GA8143@elte.hu> References: <200906162232.n5GMWRZe026963@imap1.linux-foundation.org> <20090616223649.719ea378.akpm@linux-foundation.org> <20090617111800.GA15261@elte.hu> <20090617113120.GA5061@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Linus Torvalds wrote: > On Wed, 17 Jun 2009, Ingo Molnar wrote: > > > > a new warning started popping up today, in the new page allocator > > code. The allocation came from kmemleak: > > We should probably print out the order. > > Right now it warns about any order but 0, and I think that's > likely bogus. It's fine to allow small orders (I'd suggest 0-2), > since we should always be able to get those, and small kmalloc's > generally do want more than one page just to avoid crazy > fragmentation issues. > > See, for example, the whole 'slab_break_gfp_order' logic in > mm/slab.c: it very much expects to be able to use order-1 > allocations for kmalloc() if there is enough memory (where > "enough" is actually just 32MB). And slub seems to put some limit > at PAGE_ALLOC_COSTLY_ORDER (3). > > So apart from anything else (ie this particular case is possibly > fixable in kmemleak), I do think that we should likely allow at > least order-1 and possible order-2 allocations with __GFP_NOFAIL > too. I saw about half a dozen of different warning patterns during the day, so the warning definitely feels a bit over-eager. Ingo