From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Jessica Yu <jeyu@redhat.com>, Jiri Kosina <jikos@kernel.org>,
Miroslav Benes <mbenes@suse.cz>,
Steven Rostedt <rostedt@goodmis.org>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] livepatch/rcu: Handle some subtle issues between livepatching and RCU
Date: Thu, 4 May 2017 09:55:21 -0700 [thread overview]
Message-ID: <20170504165521.GA3956@linux.vnet.ibm.com> (raw)
In-Reply-To: <1493895316-19165-1-git-send-email-pmladek@suse.com>
On Thu, May 04, 2017 at 12:55:13PM +0200, Petr Mladek wrote:
> 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.
I don't know enough to say much about the live patching, but the
characterization of how RCU works is correct.
Thanx, Paul
> 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
>
prev parent reply other threads:[~2017-05-04 16:55 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-04 10:55 [PATCH 0/3] livepatch/rcu: Handle some subtle issues between livepatching and RCU Petr Mladek
2017-05-04 10:55 ` [PATCH 1/3] livepatch/rcu: Guarantee consistency when patching idle kthreads Petr Mladek
2017-05-04 10:55 ` [PATCH 2/3] livepatch/rcu: Warn when system consistency is broken in RCU code Petr Mladek
2017-05-08 16:51 ` Josh Poimboeuf
2017-05-08 19:13 ` Steven Rostedt
2017-05-08 19:47 ` Josh Poimboeuf
2017-05-08 20:15 ` Paul E. McKenney
2017-05-08 20:43 ` Josh Poimboeuf
2017-05-08 20:51 ` Josh Poimboeuf
2017-05-08 21:08 ` Paul E. McKenney
2017-05-08 21:07 ` Paul E. McKenney
2017-05-08 21:18 ` Steven Rostedt
2017-05-08 21:30 ` Paul E. McKenney
2017-05-08 22:16 ` Josh Poimboeuf
2017-05-08 22:36 ` Paul E. McKenney
2017-05-09 16:18 ` Josh Poimboeuf
2017-05-09 16:36 ` Paul E. McKenney
2017-05-10 16:04 ` Petr Mladek
2017-05-10 16:45 ` Paul E. McKenney
2017-05-10 17:58 ` Josh Poimboeuf
2017-05-11 12:40 ` Miroslav Benes
2017-05-11 15:03 ` Josh Poimboeuf
2017-05-08 21:16 ` Steven Rostedt
2017-05-08 20:18 ` Steven Rostedt
2017-05-11 12:50 ` Miroslav Benes
2017-05-11 13:52 ` Petr Mladek
2017-05-11 14:50 ` Paul E. McKenney
2017-05-11 15:27 ` Josh Poimboeuf
2017-05-11 12:44 ` Petr Mladek
2017-05-04 10:55 ` [PATCH 3/3] livepatch/rcu: Disable livepatch removal when safety is not guaranteed Petr Mladek
2017-05-04 16:55 ` Paul E. McKenney [this message]
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