1 files changed, 21 insertions, 16 deletions

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 5649a0371a1f..1014beb12802 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -213,7 +213,7 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 
 	if (mm) {
 		mmap_read_lock(mm);
-		vma = alloc->vma;
+		vma = vma_lookup(mm, alloc->vma_addr);
 	}
 
 	if (!vma && need_mm) {
@@ -313,16 +313,22 @@ err_no_vma:
 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
 		struct vm_area_struct *vma)
 {
-	if (vma)
-		alloc->vma_vm_mm = vma->vm_mm;
+	unsigned long vm_start = 0;
+
 	/*
-	 * If we see alloc->vma is not NULL, buffer data structures set up
-	 * completely. Look at smp_rmb side binder_alloc_get_vma.
-	 * We also want to guarantee new alloc->vma_vm_mm is always visible
-	 * if alloc->vma is set.
+	 * Allow clearing the vma with holding just the read lock to allow
+	 * munmapping downgrade of the write lock before freeing and closing the
+	 * file using binder_alloc_vma_close().
 	 */
-	smp_wmb();
-	alloc->vma = vma;
+	if (vma) {
+		vm_start = vma->vm_start;
+		alloc->vma_vm_mm = vma->vm_mm;
+		mmap_assert_write_locked(alloc->vma_vm_mm);
+	} else {
+		mmap_assert_locked(alloc->vma_vm_mm);
+	}
+
+	alloc->vma_addr = vm_start;
 }
 
 static inline struct vm_area_struct *binder_alloc_get_vma(
@@ -330,11 +336,9 @@ static inline struct vm_area_struct *binder_alloc_get_vma(
 {
 	struct vm_area_struct *vma = NULL;
 
-	if (alloc->vma) {
-		/* Look at description in binder_alloc_set_vma */
-		smp_rmb();
-		vma = alloc->vma;
-	}
+	if (alloc->vma_addr)
+		vma = vma_lookup(alloc->vma_vm_mm, alloc->vma_addr);
+
 	return vma;
 }
 
@@ -817,7 +821,8 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 
 	buffers = 0;
 	mutex_lock(&alloc->mutex);
-	BUG_ON(alloc->vma);
+	BUG_ON(alloc->vma_addr &&
+	       vma_lookup(alloc->vma_vm_mm, alloc->vma_addr));
 
 	while ((n = rb_first(&alloc->allocated_buffers))) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
@@ -1084,7 +1089,7 @@ int binder_alloc_shrinker_init(void)
 	int ret = list_lru_init(&binder_alloc_lru);
 
 	if (ret == 0) {
-		ret = register_shrinker(&binder_shrinker);
+		ret = register_shrinker(&binder_shrinker, "android-binder");
 		if (ret)
 			list_lru_destroy(&binder_alloc_lru);
 	}