Re: [PATCH -mm] Revoke core code: fix nommu arch compiling error bug

[David Howells <dhowells@redhat.com>]

Pekka J Enberg <penberg@cs.helsinki.fi> wrote:

> But what's more important is, can we do revoke_mapping() for NOMMU? AFAICT 
> we can, we just need to scan all the global vmas, right?

I don't know, what does it do?  Remember, once a NOMMU process thinks it has
the right to access a mapping, there's no way of stopping it doing so short of
killing the process.

With NOMMU as it stands, private mappings are private copies of the data, and
have no impact on the page cache and get no updates from it.  It's as if you
took a private writable mapping, touched every page and then mprotect()'d it.
This isn't necessarily ideal, but we're limited by the lack on an MMU.

David