mm: re-architect the VM_UNPAGED logic

This replaces the (in my opinion horrible) VM_UNMAPPED logic with very
explicit support for a "remapped page range" aka VM_PFNMAP.  It allows a
VM area to contain an arbitrary range of page table entries that the VM
never touches, and never considers to be normal pages.

Any user of "remap_pfn_range()" automatically gets this new
functionality, and doesn't even have to mark the pages reserved or
indeed mark them any other way.  It just works.  As a side effect, doing
mmap() on /dev/mem works for arbitrary ranges.

Sparc update from David in the next commit.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index b44b36e0c293..f0c47dab0903 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -145,8 +145,7 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
 			struct page *pg = virt_to_page(vdso32_kbase +
 						       i*PAGE_SIZE);
 			struct page *upg = (vma && vma->vm_mm) ?
-				follow_page(vma->vm_mm, vma->vm_start +
-					    i*PAGE_SIZE, 0)
+				follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
 				: NULL;
 			dump_one_vdso_page(pg, upg);
 		}
@@ -157,8 +156,7 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
 			struct page *pg = virt_to_page(vdso64_kbase +
 						       i*PAGE_SIZE);
 			struct page *upg = (vma && vma->vm_mm) ?
-				follow_page(vma->vm_mm, vma->vm_start +
-					    i*PAGE_SIZE, 0)
+				follow_page(vma, vma->vm_start + i*PAGE_SIZE, 0)
 				: NULL;
 			dump_one_vdso_page(pg, upg);
 		}