// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2013 Red Hat Inc.
*
* 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/init.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memremap.h>
#include <linux/jump_label.h>
#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
#include <linux/memory_hotplug.h>
#if IS_ENABLED(CONFIG_HMM_MIRROR)
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
static inline struct hmm *mm_get_hmm(struct mm_struct *mm)
{
struct hmm *hmm = READ_ONCE(mm->hmm);
if (hmm && kref_get_unless_zero(&hmm->kref))
return hmm;
return NULL;
}
/**
* hmm_get_or_create - register HMM against an mm (HMM internal)
*
* @mm: mm struct to attach to
* Returns: returns an HMM object, either by referencing the existing
* (per-process) object, or by creating a new one.
*
* This is not intended to be used directly by device drivers. If mm already
* has an HMM struct then it get a reference on it and returns it. Otherwise
* it allocates an HMM struct, initializes it, associate it with the mm and
* returns it.
*/
static struct hmm *hmm_get_or_create(struct mm_struct *mm)
{
struct hmm *hmm = mm_get_hmm(mm);
bool cleanup = false;
if (hmm)
return hmm;