Re: memory management issues

On Thu, 2007-05-03 at 01:11 -0700, Ollie Wild wrote:
> Is this a bug in get_user_pages()?  Should it be calling
> flush_cache_page() directly?

Just for the sake of completeness, the answer to this is "no".  The
anonymous page part of get_user_pages() is designed to gather pages from
current processes only (an then, the only in-tree user we have is fuse
and that's a bit of a hack).  The problem with your patch is that you're
trying to gather non-current pages.

It took me a while to discover this, largely because you do this:

+                               ret = get_user_pages(current, bprm->mm, pos,
+                                                    1, 1, 1, &page, NULL);

That's horribly wrong ... you can't use the current process context to
gather non-current pages ... if anything goes wrong and the page needs
faulting (unusual for a nascent process, but not impossible) you'll get
into terrible trouble because the mapping for the page isn't in current.

James