1 files changed, 41 insertions, 5 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 4aaa53a..269d049 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -379,7 +379,7 @@ static int shmem_free_swap(struct address_space *mapping,
 /*
  * Pagevec may contain swap entries, so shuffle up pages before releasing.
  */
-static void shmem_pagevec_release(struct pagevec *pvec)
+static void shmem_deswap_pagevec(struct pagevec *pvec)
 {
 	int i, j;
 
@@ -389,7 +389,36 @@ static void shmem_pagevec_release(struct pagevec *pvec)
 			pvec->pages[j++] = page;
 	}
 	pvec->nr = j;
-	pagevec_release(pvec);
+}
+
+/*
+ * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
+ */
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+	struct pagevec pvec;
+	pgoff_t indices[PAGEVEC_SIZE];
+	pgoff_t index = 0;
+
+	pagevec_init(&pvec, 0);
+	/*
+	 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
+	 */
+	while (!mapping_unevictable(mapping)) {
+		/*
+		 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
+		 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
+		 */
+		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+					PAGEVEC_SIZE, pvec.pages, indices);
+		if (!pvec.nr)
+			break;
+		index = indices[pvec.nr - 1] + 1;
+		shmem_deswap_pagevec(&pvec);
+		check_move_unevictable_pages(pvec.pages, pvec.nr);
+		pagevec_release(&pvec);
+		cond_resched();
+	}
 }
 
 /*
@@ -440,7 +469,8 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 			}
 			unlock_page(page);
 		}
-		shmem_pagevec_release(&pvec);
+		shmem_deswap_pagevec(&pvec);
+		pagevec_release(&pvec);
 		mem_cgroup_uncharge_end();
 		cond_resched();
 		index++;
@@ -470,7 +500,8 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 			continue;
 		}
 		if (index == start && indices[0] > end) {
-			shmem_pagevec_release(&pvec);
+			shmem_deswap_pagevec(&pvec);
+			pagevec_release(&pvec);
 			break;
 		}
 		mem_cgroup_uncharge_start();
@@ -494,7 +525,8 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 			}
 			unlock_page(page);
 		}
-		shmem_pagevec_release(&pvec);
+		shmem_deswap_pagevec(&pvec);
+		pagevec_release(&pvec);
 		mem_cgroup_uncharge_end();
 		index++;
 	}
@@ -2438,6 +2470,10 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user)
 	return 0;
 }
 
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+}
+
 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 {
 	truncate_inode_pages_range(inode->i_mapping, lstart, lend);