1 files changed, 81 insertions, 13 deletions

diff --git a/mm/mincore.c b/mm/mincore.c
index f0f91461a9f4..218099b5ed31 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -42,14 +42,72 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
 	return 0;
 }
 
-static int mincore_unmapped_range(unsigned long addr, unsigned long end,
-				   struct mm_walk *walk)
+/*
+ * Later we can get more picky about what "in core" means precisely.
+ * For now, simply check to see if the page is in the page cache,
+ * and is up to date; i.e. that no page-in operation would be required
+ * at this time if an application were to map and access this page.
+ */
+static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
+{
+	unsigned char present = 0;
+	struct page *page;
+
+	/*
+	 * When tmpfs swaps out a page from a file, any process mapping that
+	 * file will not get a swp_entry_t in its pte, but rather it is like
+	 * any other file mapping (ie. marked !present and faulted in with
+	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
+	 */
+#ifdef CONFIG_SWAP
+	if (shmem_mapping(mapping)) {
+		page = find_get_entry(mapping, pgoff);
+		/*
+		 * shmem/tmpfs may return swap: account for swapcache
+		 * page too.
+		 */
+		if (xa_is_value(page)) {
+			swp_entry_t swp = radix_to_swp_entry(page);
+			page = find_get_page(swap_address_space(swp),
+					     swp_offset(swp));
+		}
+	} else
+		page = find_get_page(mapping, pgoff);
+#else
+	page = find_get_page(mapping, pgoff);
+#endif
+	if (page) {
+		present = PageUptodate(page);
+		put_page(page);
+	}
+
+	return present;
+}
+
+static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
+				struct vm_area_struct *vma, unsigned char *vec)
 {
-	unsigned char *vec = walk->private;
 	unsigned long nr = (end - addr) >> PAGE_SHIFT;
+	int i;
 
-	memset(vec, 0, nr);
-	walk->private += nr;
+	if (vma->vm_file) {
+		pgoff_t pgoff;
+
+		pgoff = linear_page_index(vma, addr);
+		for (i = 0; i < nr; i++, pgoff++)
+			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+	} else {
+		for (i = 0; i < nr; i++)
+			vec[i] = 0;
+	}
+	return nr;
+}
+
+static int mincore_unmapped_range(unsigned long addr, unsigned long end,
+				   struct mm_walk *walk)
+{
+	walk->private += __mincore_unmapped_range(addr, end,
+						  walk->vma, walk->private);
 	return 0;
 }
 
@@ -69,9 +127,8 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		goto out;
 	}
 
-	/* We'll consider a THP page under construction to be there */
 	if (pmd_trans_unstable(pmd)) {
-		memset(vec, 1, nr);
+		__mincore_unmapped_range(addr, end, vma, vec);
 		goto out;
 	}
 
@@ -80,17 +137,28 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		pte_t pte = *ptep;
 
 		if (pte_none(pte))
-			*vec = 0;
+			__mincore_unmapped_range(addr, addr + PAGE_SIZE,
+						 vma, vec);
 		else if (pte_present(pte))
 			*vec = 1;
 		else { /* pte is a swap entry */
 			swp_entry_t entry = pte_to_swp_entry(pte);
 
-			/*
-			 * migration or hwpoison entries are always
-			 * uptodate
-			 */
-			*vec = !!non_swap_entry(entry);
+			if (non_swap_entry(entry)) {
+				/*
+				 * migration or hwpoison entries are always
+				 * uptodate
+				 */
+				*vec = 1;
+			} else {
+#ifdef CONFIG_SWAP
+				*vec = mincore_page(swap_address_space(entry),
+						    swp_offset(entry));
+#else
+				WARN_ON(1);
+				*vec = 1;
+#endif
+			}
 		}
 		vec++;
 	}