From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Rowand Subject: [PATCH RT 0/2][RFC] fix RCU stall warning on ARM Date: Tue, 4 Dec 2012 20:47:22 -0800 Message-ID: <50BED1DA.7070907@am.sony.com> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit To: , , , , , Return-path: Received: from [65.55.88.11] ([65.55.88.11]:5096 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753507Ab2LEEs0 (ORCPT ); Tue, 4 Dec 2012 23:48:26 -0500 Sender: linux-rt-users-owner@vger.kernel.org List-ID: The RCU stall warning functions call trigger_all_cpu_backtrace() to print a backtrace on each cpu. This function is only implemented for x86. Add a version for ARM. With CONFIG_PREEMPT_RT_FULL enabled, flushing the output from printk() is inhibited in some contexts to avoid increasing real time latencies. The RCU stall warnings are inhibited on ARM due to this feature. (I have not tested whether this is also the case on other architectures.) Add back the oops_in_progress flag to allow the RCU stall warnings to print immediately. A third patch contains test scaffolding to force the stall warnings to occur so that the other patches can be tested. The third patch should __not__ added to the mainline RT PREEMPT patch tree. These patches apply to 3.6.7-rt18. They do not apply cleanly to 3.0.xx. From mboxrd@z Thu Jan 1 00:00:00 1970 From: frank.rowand@am.sony.com (Frank Rowand) Date: Tue, 4 Dec 2012 20:47:22 -0800 Subject: [PATCH RT 0/2][RFC] fix RCU stall warning on ARM Message-ID: <50BED1DA.7070907@am.sony.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The RCU stall warning functions call trigger_all_cpu_backtrace() to print a backtrace on each cpu. This function is only implemented for x86. Add a version for ARM. With CONFIG_PREEMPT_RT_FULL enabled, flushing the output from printk() is inhibited in some contexts to avoid increasing real time latencies. The RCU stall warnings are inhibited on ARM due to this feature. (I have not tested whether this is also the case on other architectures.) Add back the oops_in_progress flag to allow the RCU stall warnings to print immediately. A third patch contains test scaffolding to force the stall warnings to occur so that the other patches can be tested. The third patch should __not__ added to the mainline RT PREEMPT patch tree. These patches apply to 3.6.7-rt18. They do not apply cleanly to 3.0.xx.