Re: [PATCH] mm/mremap: fix BUILD_BUG_ON() error in get_extent

From: Arnd Bergmann
Date: Tue Jan 05 2021 - 05:29:39 EST


On Mon, Jan 4, 2021 at 11:36 PM Nathan Chancellor
<natechancellor@xxxxxxxxx> wrote:
>
> I am in agreement with Vlastimil, I would rather see the BUILD_BUG()
> dropped or converted into BUG() instead of papering over with
> __always_inline.

I see your point, but I also generally prefer build-time checks over
runtime ones wherever possible, and would prefer a way to keep
it in a form that allows that, at least if the check is considered useful
at all.

> For what it's worth, I only see this build failure
> with CONFIG_UBSAN_UNSIGNED_OVERFLOW, which you proposed disabling:
>
> https://lore.kernel.org/lkml/20201230154749.746641-1-arnd@xxxxxxxxxx/

I'm building more randconfig kernels without this patch but with the
__always_inline
reverted now, will see if it comes back. If not, let's just drop this patch.

Arnd