Page host virtual assist: mlocked pages.

diff -urpN linux-2.6/include/linux/fs.h linux-2.6-patched/include/linux/fs.h
@@ -394,6 +394,7 @@ struct address_space {
 	spinlock_t		private_lock;	/* for use by the address_space */
 	struct list_head	private_list;	/* ditto */
 	struct address_space	*assoc_mapping;	/* ditto */
+	unsigned int		mlocked;	/* set if VM_LOCKED vmas present */
 } __attribute__((aligned(sizeof(long))));
 	/*
 	 * On most architectures that alignment is already the case; but

diff -urpN linux-2.6/mm/memory.c linux-2.6-patched/mm/memory.c
@@ -2403,6 +2403,31 @@ int make_pages_present(unsigned long add
 	BUG_ON(addr >= end);
 	BUG_ON(end > vma->vm_end);
 	len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
+
+	if (page_hva_enabled() && (vma->vm_flags & VM_LOCKED)) {
+		int rlen = len;
+		ret = 0;
+		while (rlen > 0) {
+			struct page *page_refs[32];
+			int chunk, cret, i;
+
+			chunk = rlen < 32 ? rlen : 32;
+			cret = get_user_pages(current, current->mm, addr,
+					      chunk, write, 0,
+					      page_refs, NULL);
+			if (cret > 0) {
+				for (i = 0; i < cret; i++)
+					page_cache_release(page_refs[i]);
+				ret += cret;
+			}
+			if (cret < chunk)
+				return ret ? : cret;
+			addr += 32*PAGE_SIZE;
+			rlen -= 32;
+		}
+		return ret == len ? 0 : -1;
+	}
+
 	ret = get_user_pages(current, current->mm, addr,
 			len, write, 0, NULL, NULL);
 	if (ret < 0)

diff -urpN linux-2.6/mm/mlock.c linux-2.6-patched/mm/mlock.c
@@ -60,6 +60,8 @@ success:
 	 */
 	pages = (end - start) >> PAGE_SHIFT;
 	if (newflags & VM_LOCKED) {
+		if (vma->vm_file && vma->vm_file->f_mapping)
+			vma->vm_file->f_mapping->mlocked = 1;
 		pages = -pages;
 		if (!(newflags & VM_IO))
 			ret = make_pages_present(start, end);

diff -urpN linux-2.6/mm/page_hva.c linux-2.6-patched/mm/page_hva.c
@@ -27,6 +27,8 @@
  */
 static inline int __page_hva_discardable(struct page *page,unsigned int offset)
 {
+	struct address_space *mapping;
+
 	/*
 	 * There are several conditions that prevent a page from becoming
 	 * volatile. The first check is for the page bits.

@@ -41,7 +43,8 @@ static inline int __page_hva_discardable
 	 * it volatile. It will be freed soon. If the mapping ever had
 	 * locked pages all pages of the mapping will stay stable.
 	 */
-	if (!page_mapping(page))
+	mapping = page_mapping(page);
+	if (!mapping || mapping->mlocked)
 		return 0;
 
 	/*

diff -urpN linux-2.6/mm/rmap.c linux-2.6-patched/mm/rmap.c
@@ -559,7 +559,8 @@ static int try_to_unmap_one(struct page 
 	 * If it's recently referenced (perhaps page_referenced
 	 * skipped over this mm) then we should reactivate it.
 	 */
-	if ((vma->vm_flags & VM_LOCKED) ||
+	if (((vma->vm_flags & VM_LOCKED) &&
+	     !unlikely(page_hva_enabled() && PageDiscarded(page))) ||
 			(ptep_clear_flush_young(vma, address, pte)
 				&& !migration)) {
 		ret = SWAP_FAIL;