---

yaml
---
r: 189833
b: refs/heads/master
c: 287d97a
h: refs/heads/master
i:
  189831: 9ee34fa
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d0e9fe1758f222f13ec893f856552d81a10d266d
+refs/heads/master: 287d97ac032136724143cde8d5964b414d562ee3

trunk/mm/mmap.c

@@ -507,27 +507,28 @@ int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 	struct address_space *mapping = NULL;
 	struct prio_tree_root *root = NULL;
 	struct file *file = vma->vm_file;
-	struct anon_vma *anon_vma = NULL;
 	long adjust_next = 0;
 	int remove_next = 0;
 
 	if (next && !insert) {
+		struct vm_area_struct *exporter = NULL;
+
 		if (end >= next->vm_end) {
 			/*
 			 * vma expands, overlapping all the next, and
 			 * perhaps the one after too (mprotect case 6).
 			 */
 again:			remove_next = 1 + (end > next->vm_end);
 			end = next->vm_end;
-			anon_vma = next->anon_vma;
+			exporter = next;
 			importer = vma;
 		} else if (end > next->vm_start) {
 			/*
 			 * vma expands, overlapping part of the next:
 			 * mprotect case 5 shifting the boundary up.
 			 */
 			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
-			anon_vma = next->anon_vma;
+			exporter = next;
 			importer = vma;
 		} else if (end < vma->vm_end) {
 			/*
@@ -536,28 +537,19 @@ again:			remove_next = 1 + (end > next->vm_end);
 			 * mprotect case 4 shifting the boundary down.
 			 */
 			adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
-			anon_vma = next->anon_vma;
+			exporter = vma;
 			importer = next;
 		}
-	}
 
-	/*
-	 * When changing only vma->vm_end, we don't really need anon_vma lock.
-	 */
-	if (vma->anon_vma && (insert || importer || start != vma->vm_start))
-		anon_vma = vma->anon_vma;
-	if (anon_vma) {
 		/*
 		 * Easily overlooked: when mprotect shifts the boundary,
 		 * make sure the expanding vma has anon_vma set if the
 		 * shrinking vma had, to cover any anon pages imported.
 		 */
-		if (importer && !importer->anon_vma) {
-			/* Block reverse map lookups until things are set up. */
-			if (anon_vma_clone(importer, vma)) {
+		if (exporter && exporter->anon_vma && !importer->anon_vma) {
+			if (anon_vma_clone(importer, exporter))
 				return -ENOMEM;
-			}
-			importer->anon_vma = anon_vma;
+			importer->anon_vma = exporter->anon_vma;
 		}
 	}