Re: [PATCH] xen: unexport __init-annotated xen_xlate_map_ballooned_pages()

From: Juergen Gross
Date: Wed Jun 08 2022 - 03:06:53 EST


On 06.06.22 06:59, Masahiro Yamada wrote:
EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

- Remove __init
- Remove EXPORT_SYMBOL

I chose the latter for this case because none of the in-tree call-sites
(arch/arm/xen/enlighten.c, arch/x86/xen/grant-table.c) is compiled as
modular.

Fixes: 243848fc018c ("xen/grant-table: Move xlated_setup_gnttab_pages to common place")
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>

Pushed to xen/tip.git for-linus-5.19a


Juergen

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