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Date:   Mon, 22 Mar 2021 15:06:36 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Jessica Yu <jeyu@kernel.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>, x86@kernel.org,
        jbaron@akamai.com, ardb@kernel.org, linux-kernel@vger.kernel.org,
        sumit.garg@linaro.org, oliver.sang@intel.com, jarkko@kernel.org
Subject: Re: [PATCH 3/3] static_call: Fix static_call_update() sanity check
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On Mon, Mar 22, 2021 at 02:07:54PM +0100, Jessica Yu wrote:
> +++ Steven Rostedt [19/03/21 14:00 -0400]:
> > On Fri, 19 Mar 2021 13:57:38 +0100
> > Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > > Jessica, can you explain how !MODULE_UNLOAD is supposed to work?
> > > Alternatives, jump_labels and static_call all can have relocations into
> > > __exit code. Not loading it at all would be BAD.
> > 
> > According to the description:
> > 
> > " Without this option you will not be able to unload any
> >  modules (note that some modules may not be unloadable anyway), which
> >  makes your kernel smaller, faster and simpler.
> >  If unsure, say Y."
> > 
> > Seems there's no reason to load the "exit" portion, as that's what makes it
> > "smaller".
> 
> Exactly. If you disable MODULE_UNLOAD, then you don't intend to ever
> unload any modules, and so you'll never end up calling the module's
> cleanup/exit function. That code would basically be never used, so
> that's why it's not loaded in the first place.

As explained, that's broken. Has always been for as long as we've had
alternatives.