[PATCH] unpaged: VM_NONLINEAR VM_RESERVED

There's one peculiar use of VM_RESERVED which the previous patch left behind:
because VM_NONLINEAR's try_to_unmap_cluster uses vm_private_data as a swapout
cursor, but should never meet VM_RESERVED vmas, it was a way of extending
VM_NONLINEAR to VM_RESERVED vmas using vm_private_data for some other purpose.
 But that's an empty set - they don't have the populate function required.  So
just throw away those VM_RESERVED tests.

But one more interesting in rmap.c has to go too: try_to_unmap_one will want
to swap out an anonymous page from VM_RESERVED or VM_UNPAGED area.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/fremap.c

@@ -204,12 +204,10 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
 	 * Make sure the vma is shared, that it supports prefaulting,
 	 * and that the remapped range is valid and fully within
 	 * the single existing vma.  vm_private_data is used as a
-	 * swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED
-	 * or VM_LOCKED, but VM_LOCKED could be revoked later on).
+	 * swapout cursor in a VM_NONLINEAR vma.
 	 */
 	if (vma && (vma->vm_flags & VM_SHARED) &&
-		(!vma->vm_private_data ||
-			(vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) &&
+		(!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) &&
 		vma->vm_ops && vma->vm_ops->populate &&
 			end > start && start >= vma->vm_start &&
 				end <= vma->vm_end) {

mm/rmap.c

@@ -529,10 +529,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
 	 * If the page is mlock()d, we cannot swap it out.
 	 * If it's recently referenced (perhaps page_referenced
 	 * skipped over this mm) then we should reactivate it.
-	 *
-	 * Pages belonging to VM_RESERVED regions should not happen here.
 	 */
-	if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
+	if ((vma->vm_flags & VM_LOCKED) ||
 			ptep_clear_flush_young(vma, address, pte)) {
 		ret = SWAP_FAIL;
 		goto out_unmap;
@@ -727,7 +725,7 @@ static int try_to_unmap_file(struct page *page)
 
 	list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
 						shared.vm_set.list) {
-		if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
+		if (vma->vm_flags & VM_LOCKED)
 			continue;
 		cursor = (unsigned long) vma->vm_private_data;
 		if (cursor > max_nl_cursor)
@@ -761,7 +759,7 @@ static int try_to_unmap_file(struct page *page)
 	do {
 		list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
 						shared.vm_set.list) {
-			if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
+			if (vma->vm_flags & VM_LOCKED)
 				continue;
 			cursor = (unsigned long) vma->vm_private_data;
 			while ( cursor < max_nl_cursor &&
@@ -783,11 +781,8 @@ static int try_to_unmap_file(struct page *page)
 	 * in locked vmas).  Reset cursor on all unreserved nonlinear
 	 * vmas, now forgetting on which ones it had fallen behind.
 	 */
-	list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
-						shared.vm_set.list) {
-		if (!(vma->vm_flags & VM_RESERVED))
-			vma->vm_private_data = NULL;
-	}
+	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
+		vma->vm_private_data = NULL;
 out:
 	spin_unlock(&mapping->i_mmap_lock);
 	return ret;