diff --git a/src/device/virtio/blk.rs b/src/device/virtio/blk.rs
index 8b41eec23a658695bbb322cab5ae996117f5a93d..baa77531a917ceaffa05b733ce9488a1243ba8fb 100644
--- a/src/device/virtio/blk.rs
+++ b/src/device/virtio/blk.rs
@@ -32,7 +32,7 @@ pub const VIRTIO_BLK_F_SEG_MAX: usize = 1 << 2;
 /* BLOCK PARAMETERS*/
 pub const SECTOR_BSIZE: usize = 512;
 pub const BLOCKIF_SIZE_MAX: usize = 128 * PAGE_SIZE;
-pub const BLOCKIF_IOV_MAX: usize = 512;
+pub const BLOCKIF_IOV_MAX: usize = 254;
 
 /* BLOCK REQUEST TYPE*/
 pub const VIRTIO_BLK_T_IN: usize = 0;
diff --git a/src/device/virtio/mediated.rs b/src/device/virtio/mediated.rs
index aa499b4c8bd14e930b377fef5cee312c5b484ef4..2344227b6a81c73ff09c3529aa916765b1bc8baf 100644
--- a/src/device/virtio/mediated.rs
+++ b/src/device/virtio/mediated.rs
@@ -235,8 +235,6 @@ pub fn mediated_ipi_handler(msg: IpiMessage) {
     if let IpiInnerMsg::MediatedMsg(mediated_msg) = msg.ipi_message {
         // generate IO request in `virtio_blk_notify_handler`
         virtio_blk_notify_handler(mediated_msg.vq, mediated_msg.blk, mediated_msg.src_vm);
-        // mark the ipi task as finish (pop it from the ipi queue)
-        finish_async_task(true);
         // invoke the executor to do IO request
         async_task_exe();
     }
diff --git a/src/kernel/async_task.rs b/src/kernel/async_task.rs
index d6c7ef967eee6d28c58c11bc5ad0fa548c205144..87c6e9f7969e97d983351fc72fc2444136fc9580 100644
--- a/src/kernel/async_task.rs
+++ b/src/kernel/async_task.rs
@@ -401,7 +401,7 @@ pub fn async_task_exe() {
         }
         drop(ipi_list);
         drop(io_list);
-        if task.handle() || (ipi && active_vm_id() == 0) {
+        if task.handle() || ipi {
             // task finish
             finish_async_task(ipi);
         } else {