1 files changed, 74 insertions, 0 deletions

diff --git a/mm/hmm.c b/mm/hmm.c
new file mode 100644
index 000000000000..de032ff9e576
--- /dev/null
+++ b/mm/hmm.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Authors: Jérôme Glisse <jglisse@redhat.com>
+ */
+/*
+ * Refer to include/linux/hmm.h for information about heterogeneous memory
+ * management or HMM for short.
+ */
+#include <linux/mm.h>
+#include <linux/hmm.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+
+
+#ifdef CONFIG_HMM
+/*
+ * struct hmm - HMM per mm struct
+ *
+ * @mm: mm struct this HMM struct is bound to
+ */
+struct hmm {
+	struct mm_struct	*mm;
+};
+
+/*
+ * hmm_register - register HMM against an mm (HMM internal)
+ *
+ * @mm: mm struct to attach to
+ *
+ * This is not intended to be used directly by device drivers. It allocates an
+ * HMM struct if mm does not have one, and initializes it.
+ */
+static struct hmm *hmm_register(struct mm_struct *mm)
+{
+	if (!mm->hmm) {
+		struct hmm *hmm = NULL;
+
+		hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
+		if (!hmm)
+			return NULL;
+		hmm->mm = mm;
+
+		spin_lock(&mm->page_table_lock);
+		if (!mm->hmm)
+			mm->hmm = hmm;
+		else
+			kfree(hmm);
+		spin_unlock(&mm->page_table_lock);
+	}
+
+	/*
+	 * The hmm struct can only be freed once the mm_struct goes away,
+	 * hence we should always have pre-allocated an new hmm struct
+	 * above.
+	 */
+	return mm->hmm;
+}
+
+void hmm_mm_destroy(struct mm_struct *mm)
+{
+	kfree(mm->hmm);
+}
+#endif /* CONFIG_HMM */