diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index 2a9f460cf061..be34f99ca625 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -39,6 +39,8 @@
 #include <rdma/ib_smi.h>
 #include <rdma/ib_umem.h>
 #include <rdma/ib_user_verbs.h>
+
+#include <linux/sched.h>
 #include <linux/mm.h>
 
 #include "mthca_dev.h"
@@ -367,6 +369,8 @@ static struct ib_ucontext *mthca_alloc_ucontext(struct ib_device *ibdev,
 		return ERR_PTR(-EFAULT);
 	}
 
+	context->reg_mr_warned = 0;
+
 	return &context->ibucontext;
 }
 
@@ -1013,7 +1017,15 @@ static struct ib_mr *mthca_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 	int err = 0;
 	int write_mtt_size;
 
-	if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd))
+	if (udata->inlen - sizeof (struct ib_uverbs_cmd_hdr) < sizeof ucmd) {
+		if (!to_mucontext(pd->uobject->context)->reg_mr_warned) {
+			mthca_warn(dev, "Process '%s' did not pass in MR attrs.\n",
+				   current->comm);
+			mthca_warn(dev, "  Update libmthca to fix this.\n");
+		}
+		++to_mucontext(pd->uobject->context)->reg_mr_warned;
+		ucmd.mr_attrs = 0;
+	} else if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd))
 		return ERR_PTR(-EFAULT);
 
 	mr = kmalloc(sizeof *mr, GFP_KERNEL);
diff --git a/drivers/infiniband/hw/mthca/mthca_provider.h b/drivers/infiniband/hw/mthca/mthca_provider.h
index 262616c8ebb6..934bf9544037 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.h
+++ b/drivers/infiniband/hw/mthca/mthca_provider.h
@@ -67,6 +67,7 @@ struct mthca_ucontext {
 	struct ib_ucontext          ibucontext;
 	struct mthca_uar            uar;
 	struct mthca_user_db_table *db_tab;
+	int			    reg_mr_warned;
 };
 
 struct mthca_mtt;
diff --git a/drivers/infiniband/hw/mthca/mthca_user.h b/drivers/infiniband/hw/mthca/mthca_user.h
index f8cb3b664d37..e1262c942db8 100644
--- a/drivers/infiniband/hw/mthca/mthca_user.h
+++ b/drivers/infiniband/hw/mthca/mthca_user.h
@@ -41,7 +41,7 @@
  * Increment this value if any changes that break userspace ABI
  * compatibility are made.
  */
-#define MTHCA_UVERBS_ABI_VERSION	2
+#define MTHCA_UVERBS_ABI_VERSION	1
 
 /*
  * Make sure that all structs defined in this file remain laid out so
@@ -62,10 +62,12 @@ struct mthca_alloc_pd_resp {
 };
 
 struct mthca_reg_mr {
+/*
+ * Mark the memory region with a DMA attribute that causes
+ * in-flight DMA to be flushed when the region is written to:
+ */
+#define MTHCA_MR_DMASYNC	0x1
 	__u32 mr_attrs;
-#define MTHCA_MR_DMASYNC 0x1
-/* mark the memory region with a DMA attribute that causes
- * in-flight DMA to be flushed when the region is written to */
 	__u32 reserved;
 };