linux-kernel - Re: [PATCH 5.4 57/60] modpost: fix section mismatch check for exported init/exit sections

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Message-ID: <ef48302b-3421-ebbe-7135-1297cffba7ed@gmail.com>
Date:   Tue, 28 Jun 2022 13:32:56 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Christoph Hellwig <hch@....de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Jessica Yu <jeyu@...nel.org>
Subject: Re: [PATCH 5.4 57/60] modpost: fix section mismatch check for
 exported init/exit sections

On 6/28/22 12:11, Nick Desaulniers wrote:
> On Mon, Jun 27, 2022 at 10:03 AM Florian Fainelli <f.fainelli@...il.com> wrote:
>>
>> On 6/27/22 04:22, Greg Kroah-Hartman wrote:
>>> From: Masahiro Yamada <masahiroy@...nel.org>
>>>
>>> commit 28438794aba47a27e922857d27b31b74e8559143 upstream.
>>>
>>> Since commit f02e8a6596b7 ("module: Sort exported symbols"),
>>> EXPORT_SYMBOL* is placed in the individual section ___ksymtab(_gpl)+<sym>
>>> (3 leading underscores instead of 2).
>>>
>>> Since then, modpost cannot detect the bad combination of EXPORT_SYMBOL
>>> and __init/__exit.
>>>
>>> Fix the .fromsec field.
>>>
>>> Fixes: f02e8a6596b7 ("module: Sort exported symbols")
>>> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
>>> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
>>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>
>> This commit causes the following warning to show up on my kernel builds
>> used for testing 5.4 stable candidates:
>>
>> WARNING: vmlinux.o(___ksymtab+drm_fb_helper_modinit+0x0): Section
>> mismatch in reference from the variable __ksymtab_drm_fb_helper_modinit
>> to the function .init.text:drm_fb_helper_modinit()
>> The symbol drm_fb_helper_modinit is exported and annotated __init
>> Fix this by removing the __init annotation of drm_fb_helper_modinit or
>> drop the export.
> 
> Thanks for the report. Looks like the patch is "working as intended."
> 
> It looks like drm_fb_helper_modinit was deleted outright in
> commit bf22c9ec39da ("drm: remove drm_fb_helper_modinit")
> in v5.12-rc1.
> 
> Florian, can you test if that cherry-picks cleanly and resolves the
> issue for you?

It does and it does, thanks!

> 
> Maybe let's check with Christoph if it's ok to backport bf22c9ec39da
> to stable 5.10 and 5.4?
> 
>>
>> The kernel configuration to reproduce this is located here (this is 5.10
>> but works in 5.4 as well):
>>
>> https://gist.github.com/2c3e8edd5ceb089c8040db724073d941
>>
>> Same applies to the 5.10, 5.15 and 5.18 stable queues FWIW.
>> --
>> Florian
> 
> 
> 


-- 
Florian