1 files changed, 29 insertions, 35 deletions

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 55a3c3c2409f..662a2a2e2e84 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -212,8 +212,8 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		mm = alloc->mm;
 
 	if (mm) {
-		mmap_read_lock(mm);
-		vma = vma_lookup(mm, alloc->vma_addr);
+		mmap_write_lock(mm);
+		vma = alloc->vma;
 	}
 
 	if (!vma && need_mm) {
@@ -270,7 +270,7 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		trace_binder_alloc_page_end(alloc, index);
 	}
 	if (mm) {
-		mmap_read_unlock(mm);
+		mmap_write_unlock(mm);
 		mmput(mm);
 	}
 	return 0;
@@ -303,21 +303,24 @@ err_page_ptr_cleared:
 	}
 err_no_vma:
 	if (mm) {
-		mmap_read_unlock(mm);
+		mmap_write_unlock(mm);
 		mmput(mm);
 	}
 	return vma ? -ENOMEM : -ESRCH;
 }
 
+static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
+		struct vm_area_struct *vma)
+{
+	/* pairs with smp_load_acquire in binder_alloc_get_vma() */
+	smp_store_release(&alloc->vma, vma);
+}
+
 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->mm, alloc->vma_addr);
-
-	return vma;
+	/* pairs with smp_store_release in binder_alloc_set_vma() */
+	return smp_load_acquire(&alloc->vma);
 }
 
 static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
@@ -380,15 +383,13 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
 	size_t size, data_offsets_size;
 	int ret;
 
-	mmap_read_lock(alloc->mm);
+	/* Check binder_alloc is fully initialized */
 	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 *));
@@ -778,7 +779,9 @@ 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;
-	alloc->vma_addr = vma->vm_start;
+
+	/* Signal binder_alloc is fully initialized */
+	binder_alloc_set_vma(alloc, vma);
 
 	return 0;
 
@@ -808,8 +811,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 
 	buffers = 0;
 	mutex_lock(&alloc->mutex);
-	BUG_ON(alloc->vma_addr &&
-	       vma_lookup(alloc->mm, alloc->vma_addr));
+	BUG_ON(alloc->vma);
 
 	while ((n = rb_first(&alloc->allocated_buffers))) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
@@ -916,25 +918,17 @@ void binder_alloc_print_pages(struct seq_file *m,
 	 * Make sure the binder_alloc is fully initialized, otherwise we might
 	 * read inconsistent state.
 	 */
-
-	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++;
+	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++;
+		}
 	}
-
-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);
@@ -969,7 +963,7 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
  */
 void binder_alloc_vma_close(struct binder_alloc *alloc)
 {
-	alloc->vma_addr = 0;
+	binder_alloc_set_vma(alloc, NULL);
 }
 
 /**