From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758215AbcFANlk (ORCPT ); Wed, 1 Jun 2016 09:41:40 -0400 Received: from mail.skyhub.de ([78.46.96.112]:54694 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754093AbcFANlj (ORCPT ); Wed, 1 Jun 2016 09:41:39 -0400 Date: Wed, 1 Jun 2016 15:41:26 +0200 From: Borislav Petkov To: Guenter Roeck , Ingo Molnar Cc: linux-hwmon@vger.kernel.org, X86 ML , LKML , Rui Huang , Sherry Hurwitz Subject: Re: [PATCH] hwmon: (fam15h_power) Disable preemption when reading registers Message-ID: <20160601134126.GB22373@pd.tnic> References: <1464775486-23446-1-git-send-email-bp@alien8.de> <574EE1B3.9010704@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <574EE1B3.9010704@roeck-us.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 01, 2016 at 06:22:59AM -0700, Guenter Roeck wrote: > An explanation would be helpful. Is this a bug fix ? That's a good point - yes, it is necessary. Both smp_processor_id() *and* smp_call_function_many() need to be called with preemption disabled. It did fire the BUG thing in check_preemption_disabled() with 4.7-rc1 here without those fixes. But, we need the other patch too - "[PATCH] x86/cpu/AMD: Extend X86_FEATURE_TOPOEXT workaround to newer models" because the cpumask generation in read_registers() doesn't work on those Carrizo CPUs. IINM, the breakage came in during this merge window so we don't have to CC:stable but both should be sent to Linus as fixes for 4.7. You could sync with Ingo who takes/acks what... but they could go through tip and hwmon tree too, I don't see a hard dependency between the two - they'd only need to be in 4.7-final. Thanks. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.