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-rw-r--r--mm/hmm.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
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+++ b/mm/hmm.c
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+/*
+ * 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 */