1 files changed, 32 insertions, 42 deletions

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 1014beb12802..1c39cfce32fa 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -208,8 +208,8 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		}
 	}
 
-	if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
-		mm = alloc->vma_vm_mm;
+	if (need_mm && mmget_not_zero(alloc->mm))
+		mm = alloc->mm;
 
 	if (mm) {
 		mmap_read_lock(mm);
@@ -309,35 +309,13 @@ err_no_vma:
 	return vma ? -ENOMEM : -ESRCH;
 }
 
-
-static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
-		struct vm_area_struct *vma)
-{
-	unsigned long vm_start = 0;
-
-	/*
-	 * 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().
-	 */
-	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(
 		struct binder_alloc *alloc)
 {
 	struct vm_area_struct *vma = NULL;
 
 	if (alloc->vma_addr)
-		vma = vma_lookup(alloc->vma_vm_mm, alloc->vma_addr);
+		vma = vma_lookup(alloc->mm, alloc->vma_addr);
 
 	return vma;
 }
@@ -402,12 +380,15 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 	size_t size, data_offsets_size;
 	int ret;
 
+	mmap_read_lock(alloc->mm);
 	if (!binder_alloc_get_vma(alloc)) {
+		mmap_read_unlock(alloc->mm);
 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 				   "%d: binder_alloc_buf, no vma\n",
 				   alloc->pid);
 		return ERR_PTR(-ESRCH);
 	}
+	mmap_read_unlock(alloc->mm);
 
 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
 		ALIGN(offsets_size, sizeof(void *));
@@ -791,8 +772,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 	buffer->free = 1;
 	binder_insert_free_buffer(alloc, buffer);
 	alloc->free_async_space = alloc->buffer_size / 2;
-	binder_alloc_set_vma(alloc, vma);
-	mmgrab(alloc->vma_vm_mm);
+	alloc->vma_addr = vma->vm_start;
 
 	return 0;
 
@@ -822,7 +802,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 	buffers = 0;
 	mutex_lock(&alloc->mutex);
 	BUG_ON(alloc->vma_addr &&
-	       vma_lookup(alloc->vma_vm_mm, alloc->vma_addr));
+	       vma_lookup(alloc->mm, alloc->vma_addr));
 
 	while ((n = rb_first(&alloc->allocated_buffers))) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
@@ -872,8 +852,8 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 		kfree(alloc->pages);
 	}
 	mutex_unlock(&alloc->mutex);
-	if (alloc->vma_vm_mm)
-		mmdrop(alloc->vma_vm_mm);
+	if (alloc->mm)
+		mmdrop(alloc->mm);
 
 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
 		     "%s: %d buffers %d, pages %d\n",
@@ -929,17 +909,25 @@ void binder_alloc_print_pages(struct seq_file *m,
 	 * Make sure the binder_alloc is fully initialized, otherwise we might
 	 * read inconsistent state.
 	 */
-	if (binder_alloc_get_vma(alloc) != NULL) {
-		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
-			page = &alloc->pages[i];
-			if (!page->page_ptr)
-				free++;
-			else if (list_empty(&page->lru))
-				active++;
-			else
-				lru++;
-		}
+
+	mmap_read_lock(alloc->mm);
+	if (binder_alloc_get_vma(alloc) == NULL) {
+		mmap_read_unlock(alloc->mm);
+		goto uninitialized;
 	}
+
+	mmap_read_unlock(alloc->mm);
+	for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
+		page = &alloc->pages[i];
+		if (!page->page_ptr)
+			free++;
+		else if (list_empty(&page->lru))
+			active++;
+		else
+			lru++;
+	}
+
+uninitialized:
 	mutex_unlock(&alloc->mutex);
 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
 	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
@@ -974,7 +962,7 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
  */
 void binder_alloc_vma_close(struct binder_alloc *alloc)
 {
-	binder_alloc_set_vma(alloc, NULL);
+	alloc->vma_addr = 0;
 }
 
 /**
@@ -1011,7 +999,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 	index = page - alloc->pages;
 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
 
-	mm = alloc->vma_vm_mm;
+	mm = alloc->mm;
 	if (!mmget_not_zero(mm))
 		goto err_mmget;
 	if (!mmap_read_trylock(mm))
@@ -1080,6 +1068,8 @@ static struct shrinker binder_shrinker = {
 void binder_alloc_init(struct binder_alloc *alloc)
 {
 	alloc->pid = current->group_leader->pid;
+	alloc->mm = current->mm;
+	mmgrab(alloc->mm);
 	mutex_init(&alloc->mutex);
 	INIT_LIST_HEAD(&alloc->buffers);
 }