From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757746AbbJVNWD (ORCPT ); Thu, 22 Oct 2015 09:22:03 -0400 Received: from mail.kernel.org ([198.145.29.136]:56583 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757563AbbJVNV4 (ORCPT ); Thu, 22 Oct 2015 09:21:56 -0400 Message-Id: <20151022132044.002031045@goodmis.org> User-Agent: quilt/0.61-1 Date: Thu, 22 Oct 2015 09:20:44 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton Subject: [PATCH 0/2] [GIT PULL] tracing: Fix RCU warnings in stack tracer Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Running tests on other changes, the system locked up due to lots of warnings. It was caused by the stack tracer triggering a warning about using rcu_dereference() when RCU was not watching. This can happen due to the fact that the stack tracer uses the function tracer to check each function, and there's functions that may be called and traced when RCU stopped watching. Namely when a function is called just before going idle or to userspace and after RCU stopped watching that current CPU. The first patch makes sure that RCU is watching when the stack tracer uses RCU. The second patch is to make sure that the stack tracer does not get called by functions in NMI, as it's not NMI safe. Please pull the latest trace-fixes-v4.3-rc6 tree, which can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-fixes-v4.3-rc6 Tag SHA1: 520ef22047724f1fae143e504b4da9737e50d32c Head SHA1: 1904be1b6bb92058c8e00063dd59df2df294e258 Steven Rostedt (Red Hat) (2): tracing: Have stack tracer force RCU to be watching tracing: Do not allow stack_tracer to record stack in NMI ---- kernel/trace/trace_stack.c | 11 +++++++++++ 1 file changed, 11 insertions(+)