[parisc-linux] memory management issues

[Peter Zijlstra]

On Thu, 2007-05-03 at 14:47 -0500, James Bottomley wrote:
> On Thu, 2007-05-03 at 10:55 -0700, Ollie Wild wrote:
> > This doesn't work because we're copying between two different
> > mm_struct's.  Since we can't have both active at the same time, we
> > need to setup some sort of temporary mapping.
> > 
> > I could maybe check the vma boundaries and create new pages in the
> > kernel, but I still need to assign them to the process space to make
> > them swappable.  Since some binfmt's remove args, I'll also
> > potentially need to reload old pages, which means copy_strings() will
> > still need to call get_user_pages() to retrieve potentially swapped
> > out pages.
> 
> OK, then you'll just have to go with flush_cache_page() ... it should be
> reasonably efficient on parisc since I modified it to do non-current
> flushing (which is really what you're doing).  However, you should be
> aware that the original parisc implementation threw up its hands and
> flushed the entire cache if it found a non-current page ... so if any
> other architecture still does that, it will be remarkably inefficient
> for you ...

I think this is best; if we were to go with a parisc specific API here,
all other arches that hit this will be in pain. Better fix their
flush_cache_page() if and when it really is a problem.

Ollie, how about posting this to lkml, and get some feedback, now that
its mostly complete.