From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id EF7356B0037 for ; Tue, 12 Mar 2013 12:16:29 -0400 (EDT) Received: by mail-pb0-f44.google.com with SMTP id wz12so6919pbc.31 for ; Tue, 12 Mar 2013 09:16:29 -0700 (PDT) Date: Tue, 12 Mar 2013 09:17:02 -0700 From: Greg Kroah-Hartman Subject: Re: [PATCH] device: separate all subsys mutexes (was: Re: [BUG] potential deadlock led by cpu_hotplug lock (memcg involved)) Message-ID: <20130312161702.GA4159@kroah.com> References: <513ECCFE.3070201@huawei.com> <20130312101555.GB30758@dhcp22.suse.cz> <20130312110750.GC30758@dhcp22.suse.cz> <20130312130504.GD30758@dhcp22.suse.cz> <1363102105.24558.4.camel@laptop> <20130312154341.GB18852@kroah.com> <1363104578.24558.9.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1363104578.24558.9.camel@laptop> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Michal Hocko , Li Zefan , LKML , cgroups , linux-mm@kvack.org, KAMEZAWA Hiroyuki , Johannes Weiner , Andrew Morton , Jiri Kosina , Ingo Molnar , Kay Sievers On Tue, Mar 12, 2013 at 05:09:38PM +0100, Peter Zijlstra wrote: > On Tue, 2013-03-12 at 08:43 -0700, Greg Kroah-Hartman wrote: > > On Tue, Mar 12, 2013 at 04:28:25PM +0100, Peter Zijlstra wrote: > > > On Tue, 2013-03-12 at 14:05 +0100, Michal Hocko wrote: > > > > @@ -111,17 +111,17 @@ struct bus_type { > > > > struct iommu_ops *iommu_ops; > > > > > > > > struct subsys_private *p; > > > > + struct lock_class_key __key; > > > > }; > > > > > > Is struct bus_type constrained to static storage or can people go an > > > allocate this stuff dynamically? If so, this patch is broken. > > > > I don't think anyone is creating this dynamically, it should be static. > > Why does this matter, does the lockdep code care about where the > > variable is declared (heap vs. static)? > > Yeah, lockdep needs keys to be in static storage since its data > structures are append-only. Dynamic stuff would require being able to > remove everything related to a key so that we can re-purpose it for the > next allocation etc. Ah, that makes sense, thanks. > Lockdep will in fact warn (and disable itself) if you try and feed it > dynamic addresses, so using it like this will effectively check your > bus_type static storage 'requirement'. Ok, then it should be fine. Michal, care to redo this and resend it? thanks, greg k-h -- 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