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mm: re-architect the VM_UNPAGED logic

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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>
This commit is contained in:
Linus Torvalds
2005-11-28 14:34:23 -08:00
parent 458af5439f
commit 6aab341e0a
11 changed files with 127 additions and 146 deletions
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12
mm/msync.c
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@ -27,7 +27,6 @@ static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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 @@ again:
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 @@ static void msync_page_range(struct vm_area_struct *vma,
/* 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);