From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752839AbdEDKz6 (ORCPT ); Thu, 4 May 2017 06:55:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:42643 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751913AbdEDKzw (ORCPT ); Thu, 4 May 2017 06:55:52 -0400 From: Petr Mladek To: Josh Poimboeuf , Jessica Yu , Jiri Kosina , Miroslav Benes Cc: Steven Rostedt , "Paul E. McKenney" , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH 0/3] livepatch/rcu: Handle some subtle issues between livepatching and RCU Date: Thu, 4 May 2017 12:55:13 +0200 Message-Id: <1493895316-19165-1-git-send-email-pmladek@suse.com> X-Mailer: git-send-email 1.8.5.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Steven and Paul recently discussed some issues when using RCU functionality in ftrace handlers. A good summary can be found at https://lkml.kernel.org/r/20170412115304.3077dbc8@gandalf.local.home This discussion made us to revisit the ftrace handler used by the livepatches. Some changes seem to be needed. A perfect solution looks rather complicated. I have implemented a sub-optimal one and split it into three patches for easier review. Please, note that we were on the safe side before introducing the hybrid consistency model. The ftrace handler worked correctly with empty function stack. Also the patch removal was not possible. But we need to be more careful now. Petr Mladek (3): livepatch/rcu: Guarantee consistency when patching idle kthreads livepatch/rcu: Warn when system consistency is broken in RCU code livepatch/rcu: Disable livepatch removal when safety is not guaranteed Documentation/livepatch/livepatch.txt | 19 +++++++++++++++++++ kernel/livepatch/patch.c | 14 ++++++++++++++ kernel/livepatch/transition.c | 7 ++++++- kernel/livepatch/transition.h | 2 ++ 4 files changed, 41 insertions(+), 1 deletion(-) -- 1.8.5.6