diff --git a/fs/aio.c b/fs/aio.c
index 6e26755..6ef73fd 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -312,8 +312,10 @@ static int aio_setup_ring(struct kioctx *ctx)
 	mm_populate(ctx->mmap_base, populate);
 
 	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
+	down_read(&mm->mmap_sem);
 	ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
 				       1, 0, ctx->ring_pages, NULL);
+	up_read(&mm->mmap_sem);
 	for (i = 0; i < ctx->nr_pages; i++)
 		put_page(ctx->ring_pages[i]);