This allows iterating over all levels of the page tables. Recursion continues

This allows iterating over all levels of the page tables.  Recursion continues
to the depth of the lowest supplied callback.

This makes the page walker nearly completely generic and should allow it to
replace some other hand-rolled page table walkers.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/task_mmu.c |   89 +++++++++++++++++++++++++++++++------------
 1 file changed, 66 insertions(+), 23 deletions(-)