diff --git a/mm/shmem.c b/mm/shmem.c
index e55aa460a2c0..69106c600692 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2895,7 +2895,7 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 		}
 
 		shmem_falloc.waitq = &shmem_falloc_waitq;
-		shmem_falloc.start = unmap_start >> PAGE_SHIFT;
+		shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
 		shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
 		spin_lock(&inode->i_lock);
 		inode->i_private = &shmem_falloc;