Re: [RFC PATCH] mm/nommu: Implement just enough vmap that compressed erofs can be mounted

[Daniel Palmer]

Hi Lorenzo, (and Pedro),

On Thu, 21 May 2026 at 02:05, Lorenzo Stoakes <ljs@xxxxxxxxxx> wrote:
>
> For some reason this iddn't arrive in my inbox properly... strange? Maybe
> missing To:?

Sorry, I CC'd everyone hoping I wouldn't get grilled for the silly patch.

> > Did I miss anything massive that is going to come back and bite me?
> > Maybe it would have made more sense just to change the erofs
> > code so on !CONFIG_MMU it doesn't use vmap?
>
> I think that'd probably be better honestly. I think faking out vmalloc is more
> trouble than it's worth, and it'd probably have to be everything-or-nothing.

That makes sense.
Do you think it'd be acceptable to maybe return NULL from these
functions instead of crashing the kernel?

> But yeah would gently point you towards doing something on the fs end I think
> here :)

Noted. I think I'll at least send them a patch to make compression
support depend on CONFIG_MMU.

Thanks!

Daniel