Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757290Ab3G2PUS (ORCPT ); Mon, 29 Jul 2013 11:20:18 -0400 Received: from merlin.infradead.org ([205.233.59.134]:46298 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755547Ab3G2PUQ (ORCPT ); Mon, 29 Jul 2013 11:20:16 -0400 Date: Mon, 29 Jul 2013 17:20:01 +0200 From: Peter Zijlstra To: Michal Hocko Cc: Minchan Kim , "Aneesh Kumar K.V" , Dave Jones , Linux Kernel , linux-mm@kvack.org, Rik van Riel , KAMEZAWA Hiroyuki , Hillf Danton , Andrew Morton Subject: Re: hugepage related lockdep trace. Message-ID: <20130729152001.GC22156@laptop.programming.kicks-ass.net> References: <20130717153223.GD27731@redhat.com> <20130718000901.GA31972@blaptop> <87hafrdatb.fsf@linux.vnet.ibm.com> <20130719001303.GB23354@blaptop> <20130723140120.GG8677@dhcp22.suse.cz> <20130724024428.GA14795@bbox> <20130725133040.GI12818@dhcp22.suse.cz> <20130729082453.GB29129@bbox> <20130729145308.GG4678@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130729145308.GG4678@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1022 Lines: 25 On Mon, Jul 29, 2013 at 04:53:08PM +0200, Michal Hocko wrote: > Peter, for you context the lockdep splat has been reported > here: https://lkml.org/lkml/2013/7/17/381 > > Minchan has proposed to workaround it by using SINGLE_DEPTH_NESTING > https://lkml.org/lkml/2013/7/23/812 > > my idea was to use a separate class key for hugetlb as it is quite > special in many ways: > https://lkml.org/lkml/2013/7/25/277 > > What is the preferred way of fixing such an issue? The class is the safer annotation. That said; it is a rather horrible issue any which way. This PMD sharing is very unique to hugetlbfs (also is that really worth the effort these days?) and it will make it impossible to make hugetlbfs swappable. The other solution is to make the pmd allocation GFP_NOFS. -- 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/