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>
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 29c3b63..91dd669 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -591,7 +591,7 @@
if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
goto out_up;
- if (vma->vm_flags & (VM_SHARED | VM_HUGETLB | VM_UNPAGED))
+ if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
break;
count = vma->vm_end - addr;
if (count > size)