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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 */
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