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, 1 insertions, 1 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index 328a3bcce527..2b7cf0400a21 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -126,7 +126,7 @@ static long madvise_dontneed(struct vm_area_struct * vma,
                              unsigned long start, unsigned long end)
 {
         *prev = vma;
-        if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_UNPAGED))
+        if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
                 return -EINVAL;
 
         if (unlikely(vma->vm_flags & VM_NONLINEAR)) {