linux-kernel - Re: [GIT PULL] Modules updates for v5.13

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Date:   Mon, 3 May 2021 12:13:34 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] Modules updates for v5.13

+++ Linus Torvalds [30/04/21 12:37 -0700]:
>On Wed, Apr 28, 2021 at 5:58 AM Jessica Yu <jeyu@...nel.org> wrote:
>>
>>    Therefore, load the __exit sections even when
>>    CONFIG_MODULE_UNLOAD=n, and discard them after init.

Hi Linus,

>So I've pulled this, but I have two questions based on reading the patch..
>
> (a) Where's that "discard them after init" logic?

So the idea is for the exit sections to additionally identify as init
sections via module_init_section() when CONFIG_MODULE_UNLOAD=n, so
that the existing logic in layout_sections() picks this up and puts
the exit sections into the init area of the module (mod->init_layout.base).

Then, since we've placed the exit sections in the init region of the
module, they will automatically get freed at the end of
do_init_module() with the rest of the init sections. Peter has also
mentioned that jump_label and static_call want the exit sections to
also identify as init via within_module_init(), so this change should
satisfy their requirement as well. I should have explained this more
in the changelog and apologize that it wasn't clear.

> (b) ARM has its own module_init/exit_section() functions, and now
>seems to have different logic than everybody else as a result..

No, you are right, I had forgotten that ARM is a special case :-( I
will add a similar hunk for ARM and submit that for the next -rc so
that all arches are on the same page here.

Jessica