Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753248AbaAZUVp (ORCPT ); Sun, 26 Jan 2014 15:21:45 -0500 Received: from mail-ea0-f179.google.com ([209.85.215.179]:40433 "EHLO mail-ea0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752826AbaAZUVo (ORCPT ); Sun, 26 Jan 2014 15:21:44 -0500 Date: Sun, 26 Jan 2014 21:21:40 +0100 From: Ingo Molnar To: Prarit Bhargava Cc: Yinghai Lu , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH -v2] x86: allocate cpumask during check irq vectors Message-ID: <20140126202140.GB8224@gmail.com> References: <1390611565-18709-1-git-send-email-yinghai@kernel.org> <20140125080232.GA20935@gmail.com> <52E4FE02.2020004@redhat.com> <20140126133203.GA1370@gmail.com> <52E55FB1.4060404@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52E55FB1.4060404@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Prarit Bhargava wrote: > > > On 01/26/2014 08:32 AM, Ingo Molnar wrote: > > > > * Prarit Bhargava wrote: > > > >> On 01/25/2014 03:02 AM, Ingo Molnar wrote: > >>> > >>> * Yinghai Lu wrote: > >>> > >>>> Fix warning: > >>>> arch/x86/kernel/irq.c: In function check_irq_vectors_for_cpu_disable: > >>>> arch/x86/kernel/irq.c:337:1: warning: the frame size of 2052 bytes is larger than 2048 bytes > >>>> > >>>> when NR_CPUS=8192 > >>>> > >>>> We should use zalloc_cpumask_var() instead. > >>>> > >>>> -v2: update to GFP_ATOMIC instead and free the allocated cpumask at last. > >>>> > >>>> Signed-off-by: Yinghai Lu > >>>> Cc: Prarit Bhargava > >>>> > >>>> --- > >>>> arch/x86/kernel/irq.c | 24 +++++++++++++++++------- > >>>> 1 file changed, 17 insertions(+), 7 deletions(-) > >>>> > >>>> Index: linux-2.6/arch/x86/kernel/irq.c > >>>> =================================================================== > >>>> --- linux-2.6.orig/arch/x86/kernel/irq.c > >>>> +++ linux-2.6/arch/x86/kernel/irq.c > >>>> @@ -277,11 +277,18 @@ int check_irq_vectors_for_cpu_disable(vo > >>>> unsigned int this_cpu, vector, this_count, count; > >>>> struct irq_desc *desc; > >>>> struct irq_data *data; > >>>> - struct cpumask affinity_new, online_new; > >>>> + cpumask_var_t affinity_new, online_new; > >>>> + > >>>> + if (!alloc_cpumask_var(&affinity_new, GFP_ATOMIC)) > >>>> + return -ENOMEM; > >>>> + if (!alloc_cpumask_var(&online_new, GFP_ATOMIC)) { > >>>> + free_cpumask_var(affinity_new); > >>>> + return -ENOMEM; > >>>> + } > >>> > >>> Atomic allocations can fail easily if the system is under duress. > >> > >> Then the hotplug attempt will fail which IMO is okay. [...] > > > > Which is not OK at all for reliable operation, if the system has > > otherwise gobs of RAM, which just don't happen to be atomic > > allocatable! > > Ingo, I'm really not sure what other option there is here. Care to > suggest one? Since only ever a single instance of this code will run, can it simply be a global cpumask_t variable? Thanks, Ingo -- 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/