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From: Rusty Russell <rusty@rustcorp.com.au>
To: Jessica Yu <jeyu@redhat.com>, Josh Poimboeuf <jpoimboe@redhat.com>,
        Seth Jennings <sjenning@redhat.com>, Jiri Kosina <jikos@kernel.org>,
        Vojtech Pavlik <vojtech@suse.com>, Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>
Cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jessica Yu <jeyu@redhat.com>
Subject: Re: [PATCH v4 4/4] livepatch/module: remove livepatch module notifier
In-Reply-To: <1454993424-31031-5-git-send-email-jeyu@redhat.com>
References: <1454993424-31031-1-git-send-email-jeyu@redhat.com> <1454993424-31031-5-git-send-email-jeyu@redhat.com>
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Date: Wed, 10 Feb 2016 10:13:12 +1030
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Jessica Yu <jeyu@redhat.com> writes:
> Remove the livepatch module notifier in favor of directly enabling and
> disabling patches to modules in the module loader. Hard-coding the
> function calls ensures that ftrace_module_enable() is run before
> klp_module_coming() during module load, and that klp_module_going() is
> run before ftrace_release_mod() during module unload. This way, ftrace
> and livepatch code is run in the correct order during the module
> load/unload sequence without dependence on the module notifier call chain.
>
> This fixes a notifier ordering issue in which the ftrace module notifier
> (and hence ftrace_module_enable()) for coming modules was being called
> after klp_module_notify(), which caused livepatch modules to initialize
> incorrectly.

Without a Fixes: line, it's not absolutely clear whether this needs
CC:stable, needs to go to Linus now, or can wait for the next merge
window.

I *think* you want all four merged this merge window, and 3 and 4 are
required to fix a regression introduced since 4.4...

Sorry for being obtuse!
Rusty.