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++;
         }