Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932488AbaGWRMh (ORCPT ); Wed, 23 Jul 2014 13:12:37 -0400 Received: from mail-vc0-f174.google.com ([209.85.220.174]:36249 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932145AbaGWRMg (ORCPT ); Wed, 23 Jul 2014 13:12:36 -0400 MIME-Version: 1.0 In-Reply-To: <20140723170324.GZ3935@laptop> References: <20140723082819.GR3935@laptop> <20140723092536.GO12054@laptop.lan> <53CF80EE.5050702@daenzer.net> <53CF844A.5050106@arm.com> <20140723111110.GT3935@laptop> <20140723113021.GP12054@laptop.lan> <20140723142454.GQ12054@laptop.lan> <20140723155526.GW3935@laptop> <20140723170324.GZ3935@laptop> Date: Wed, 23 Jul 2014 10:12:35 -0700 X-Google-Sender-Auth: dLiuLm37tTKliK7Txc5UEGJv_Lk Message-ID: Subject: Re: Random panic in load_balance() with 3.16-rc From: Linus Torvalds To: Peter Zijlstra Cc: Dietmar Eggemann , =?UTF-8?Q?Michel_D=C3=A4nzer?= , Ingo Molnar , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 23, 2014 at 10:03 AM, Peter Zijlstra wrote: > On Wed, Jul 23, 2014 at 09:54:23AM -0700, Linus Torvalds wrote: >> >> And I wonder if I have a clue. Look, load_balance_mask is a >> "cpumask_var_t", but I don't see a "alloc_cpumask_var()" for it. >> That's broken with CONFIG_CPUMASK_OFFSTACK. > > kernel/sched/core.c:sched_init() > > plays horrible allocation tricks.. No it does not. It allocates a cpumask. Nothing more. If you think it allocates a "cpumask_var()", you are wrong. I agree that the code is an unreadable mess, but that's what "cpumask_size()" is: the minimum required size of the bitmask in a cpumask. A cpumask_var is TOTALLY DIFFERENT. It's *either* a cpumask _or_ just a pointer to an externally allocated cpumask. sched_init() definitely does _not_ allocate a cpumask_var. Linus -- 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/