[PATCH] powerpc: Fix size check for hugetlbfs

My "slices" address space management code that was added in 2.6.22
implementation of get_unmapped_area() doesn't properly check that the
size is a multiple of the requested page size. This allows userland to
create VMAs that aren't a multiple of the huge page size with hugetlbfs
(since hugetlbfs entirely relies on get_unmapped_area() to do that
checking) which leads to a kernel BUG() when such areas are torn down.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

This should go to 2.6.22.x stable in addition to current 2.6.23-*

Index: linux-work/arch/powerpc/mm/slice.c
===================================================================

--- linux-work.orig/arch/powerpc/mm/slice.c	2007-08-08 15:16:06.000000000 +1000
+++ linux-work/arch/powerpc/mm/slice.c	2007-08-08 15:16:41.000000000 +1000

@@ -405,6 +405,8 @@ unsigned long slice_get_unmapped_area(un
 
 	if (len > mm->task_size)
 		return -ENOMEM;
+	if (len & ((1ul << pshift) - 1))
+		return -EINVAL;
 	if (fixed && (addr & ((1ul << pshift) - 1)))
 		return -EINVAL;
 	if (fixed && addr > (mm->task_size - len))