Re: [RFC][PATCH 1/5] pagemap: remove file header

[Dave Hansen <haveblue@us.ibm.com>]

On Wed, 2007-08-08 at 09:34 -0700, Dave Hansen wrote:
> On Wed, 2007-08-08 at 02:31 +0100, Alan Cox wrote:
> > The information needed to parse /proc/pid/pagemap can be stuck
> > in /proc/pid/somewherelese. If we ever get page size variations and the
> > like then /proc/pid/ is going to end up with that information anyway for
> > ps and friends to use.
> 
> We do at least have some of this with hugetlbfs.  In fact, the current
> pagemap code bugs out when it hits a huge page area:
> 
> /home/dave/work/linux/2.6/22/lxc/mm/memory.c:117: bad pgd 1d0000e7.
> 
> I'll look at fixing that.

I figure we have three options:

1. ignore huge pages completely
2. teach the ->pte_entry handler that ptes can be different sizes,
   and pass the huge ptes into there
3. let the ->pmd_entry handler (or whatever level we've stuck the huge
   page entry in) handle it
4. create new handlers for large pages, like ->huge_pte_entry.  This
   works for now, but what would we do if we have multiple/variable
   large page sizes?

Any other thoughts?

-- Dave