From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753360Ab1FPMpA (ORCPT ); Thu, 16 Jun 2011 08:45:00 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:53775 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287Ab1FPMo5 (ORCPT ); Thu, 16 Jun 2011 08:44:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=KAv9BXwKfjytP3udq00/91icGNKnHHtbQHBrhjQGQFjX+ioaK+t9Qhw2BVnVM3lr/+ 7xn/ulFtvs0bD0ytrTkkgdKFzCtcGNo8JyepGOl5H6UO2tG7WGsXWH5n7QQdSnnD8BzV KZ+gVbwggBMGVpcivCUf9gLbYJgIoRzJXCiDw= Date: Thu, 16 Jun 2011 14:44:52 +0200 From: Tejun Heo To: Peter Zijlstra Cc: x86@kernel.org, mingo@elte.hu, akpm@linux-foundation.org, torvalds@linux-foundation.org, suresh.b.siddha@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] stop_machine: kill __stop_machine() Message-ID: <20110616124452.GC2611@htj.dyndns.org> References: <1308071218-5912-1-git-send-email-tj@kernel.org> <1308071218-5912-2-git-send-email-tj@kernel.org> <1308226372.13240.42.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1308226372.13240.42.camel@twins> 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 On Thu, Jun 16, 2011 at 02:12:52PM +0200, Peter Zijlstra wrote: > On Tue, 2011-06-14 at 19:06 +0200, Tejun Heo wrote: > > +++ b/arch/x86/kernel/alternative.c > > @@ -719,8 +719,7 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) > > tpp.nparams = 1; > > atomic_set(&stop_machine_first, 1); > > wrote_text = 0; > > - /* Use __stop_machine() because the caller already got online_cpus. */ > > - __stop_machine(stop_machine_text_poke, (void *)&tpp, cpu_online_mask); > > + stop_machine(stop_machine_text_poke, (void *)&tpp, cpu_online_mask); > > return addr; > > } > > Please have a look at: > > --- > commit d91309f69b7bdb64aeb30106fde8d18c5dd354b5 > Author: Peter Zijlstra > Date: Fri Feb 11 22:07:46 2011 +0100 > > x86: Fix text_poke_smp_batch() deadlock > > Fix this deadlock - we are already holding the mutex: Ah, right, I thought cpu_hotplug_begin() sets active_writer and then returns with cpu_hotplug.lock released. Weird locking there. Anyways, this one should be dropped then and I don't think it affects the rest of the series much. Thanks. -- tejun