From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757205AbaCRViD (ORCPT ); Tue, 18 Mar 2014 17:38:03 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60665 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751589AbaCRViA (ORCPT ); Tue, 18 Mar 2014 17:38:00 -0400 Date: Tue, 18 Mar 2014 14:37:59 -0700 From: Andrew Morton To: Christoph Lameter Cc: Grygorii Strashko , linux-arm , Tejun Heo , linux-kernel@vger.kernel.org, Santosh Shilimkar , Ingo Molnar Subject: Re: [linux-next][regression] [PATCH] percpu: add preemption checks to __this_cpu ops Message-Id: <20140318143759.04a892434d84a9fd3aa94262@linux-foundation.org> In-Reply-To: References: <53285FE7.5010203@ti.com> <53286ABF.3040408@ti.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 18 Mar 2014 10:54:06 -0500 (CDT) Christoph Lameter wrote: > On Tue, 18 Mar 2014, Grygorii Strashko wrote: > > > Any way, I can boot and console works fine with your change :) > > Thanks. > > Ok here is the properly formatted patch: > > > Subject: preemption_checks: Avoid snprintf before checking error conditions > > snprintf can cause hangs. This is weird. How the heck can snprintf() fail if called too early? All it does is shuffle chars around in memory. The only external dependency I'm seeing is a WARN_ON() which presumably didn't trigger anyway. I'm suspecting a misdiagnosis here. Otherwise, we seriously need to fix snprintf(), not work around it! Also, what does "before checking error conditions" refer to? Does this mean you know why snprintf() failed?? > Move the string processing into the function > so that the string operations only occur when necessary after the > conditions have been checked. > > Tested-by: Grygorii Strashko Grygorii, thanks for testing linux-next on unusual machines - it's most helpful. > Signed-off-by: Christoph Lameter