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/mm/msync.c b/mm/msync.c
index b3f4caf..1b5b6f6 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -27,7 +27,6 @@
again:
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
do {
- unsigned long pfn;
struct page *page;
if (progress >= 64) {
@@ -40,13 +39,9 @@
continue;
if (!pte_maybe_dirty(*pte))
continue;
- pfn = pte_pfn(*pte);
- if (unlikely(!pfn_valid(pfn))) {
- print_bad_pte(vma, *pte, addr);
+ page = vm_normal_page(vma, addr, *pte);
+ if (!page)
continue;
- }
- page = pfn_to_page(pfn);
-
if (ptep_clear_flush_dirty(vma, addr, pte) ||
page_test_and_clear_dirty(page))
set_page_dirty(page);
@@ -97,9 +92,8 @@
/* For hugepages we can't go walking the page table normally,
* but that's ok, hugetlbfs is memory based, so we don't need
* to do anything more on an msync().
- * Can't do anything with VM_UNPAGED regions either.
*/
- if (vma->vm_flags & (VM_HUGETLB|VM_UNPAGED))
+ if (vma->vm_flags & VM_HUGETLB)
return;
BUG_ON(addr >= end);