#include <linux/mmu_notifier.h>
#include <linux/memory_hotplug.h>
-static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
-
-/**
- * hmm_get_or_create - register HMM against an mm (HMM internal)
- *
- * @mm: mm struct to attach to
- * Return: 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)
+static struct mmu_notifier *hmm_alloc_notifier(struct mm_struct *mm)
{
struct hmm *hmm;
- lockdep_assert_held_write(&mm->mmap_sem);
-
- /* Abuse the page_table_lock to also protect mm->hmm. */
- spin_lock(&mm->page_table_lock);
- hmm = mm->hmm;
- if (mm->hmm && kref_get_unless_zero(&mm->hmm->kref))
- goto out_unlock;
- spin_unlock(&mm->page_table_lock);
-
- hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
+ hmm = kzalloc(sizeof(*hmm), GFP_KERNEL);
if (!hmm)
- return NULL;
+ return ERR_PTR(-ENOMEM);
+
init_waitqueue_head(&hmm->wq);
INIT_LIST_HEAD(&hmm->mirrors);
init_rwsem(&hmm->mirrors_sem);
- hmm->mmu_notifier.ops = NULL;
INIT_LIST_HEAD(&hmm->ranges);
spin_lock_init(&hmm->ranges_lock);
- kref_init(&hmm->kref);
hmm->notifiers = 0;
- hmm->mm = mm;
-
- hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
- if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
- kfree(hmm);
- return NULL;
- }
-
- mmgrab(hmm->mm);
-
- /*
- * We hold the exclusive mmap_sem here so we know that mm->hmm is
- * still NULL or 0 kref, and is safe to update.
- */
- spin_lock(&mm->page_table_lock);
- mm->hmm = hmm;
-
-out_unlock:
- spin_unlock(&mm->page_table_lock);
- return hmm;
+ return &hmm->mmu_notifier;
}
-static void hmm_free_rcu(struct rcu_head *rcu)
+static void hmm_free_notifier(struct mmu_notifier *mn)
{
- struct hmm *hmm = container_of(rcu, struct hmm, rcu);
+ struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
- mmdrop(hmm->mm);
+ WARN_ON(!list_empty(&hmm->ranges));
+ WARN_ON(!list_empty(&hmm->mirrors));
kfree(hmm);
}
-static void hmm_free(struct kref *kref)
-{
- struct hmm *hmm = container_of(kref, struct hmm, kref);
-
- spin_lock(&hmm->mm->page_table_lock);
- if (hmm->mm->hmm == hmm)
- hmm->mm->hmm = NULL;
- spin_unlock(&hmm->mm->page_table_lock);
-
- mmu_notifier_unregister_no_release(&hmm->mmu_notifier, hmm->mm);
- mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu);
-}
-
-static inline void hmm_put(struct hmm *hmm)
-{
- kref_put(&hmm->kref, hmm_free);
-}
-
static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
struct hmm_mirror *mirror;
- /* Bail out if hmm is in the process of being freed */
- if (!kref_get_unless_zero(&hmm->kref))
- return;
-
/*
* Since hmm_range_register() holds the mmget() lock hmm_release() is
* prevented as long as a range exists.
mirror->ops->release(mirror);
}
up_read(&hmm->mirrors_sem);
-
- hmm_put(hmm);
}
static void notifiers_decrement(struct hmm *hmm)
unsigned long flags;
int ret = 0;
- if (!kref_get_unless_zero(&hmm->kref))
- return 0;
-
spin_lock_irqsave(&hmm->ranges_lock, flags);
hmm->notifiers++;
list_for_each_entry(range, &hmm->ranges, list) {
out:
if (ret)
notifiers_decrement(hmm);
- hmm_put(hmm);
return ret;
}
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
- if (!kref_get_unless_zero(&hmm->kref))
- return;
-
notifiers_decrement(hmm);
- hmm_put(hmm);
}
static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
.release = hmm_release,
.invalidate_range_start = hmm_invalidate_range_start,
.invalidate_range_end = hmm_invalidate_range_end,
+ .alloc_notifier = hmm_alloc_notifier,
+ .free_notifier = hmm_free_notifier,
};
/*
*
* To start mirroring a process address space, the device driver must register
* an HMM mirror struct.
+ *
+ * The caller cannot unregister the hmm_mirror while any ranges are
+ * registered.
+ *
+ * Callers using this function must put a call to mmu_notifier_synchronize()
+ * in their module exit functions.
*/
int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
{
+ struct mmu_notifier *mn;
+
lockdep_assert_held_write(&mm->mmap_sem);
/* Sanity check */
if (!mm || !mirror || !mirror->ops)
return -EINVAL;
- mirror->hmm = hmm_get_or_create(mm);
- if (!mirror->hmm)
- return -ENOMEM;
+ mn = mmu_notifier_get_locked(&hmm_mmu_notifier_ops, mm);
+ if (IS_ERR(mn))
+ return PTR_ERR(mn);
+ mirror->hmm = container_of(mn, struct hmm, mmu_notifier);
down_write(&mirror->hmm->mirrors_sem);
list_add(&mirror->list, &mirror->hmm->mirrors);
down_write(&hmm->mirrors_sem);
list_del(&mirror->list);
up_write(&hmm->mirrors_sem);
- hmm_put(hmm);
+ mmu_notifier_put(&hmm->mmu_notifier);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
return -EINVAL;
/* Prevent hmm_release() from running while the range is valid */
- if (!mmget_not_zero(hmm->mm))
+ if (!mmget_not_zero(hmm->mmu_notifier.mm))
return -EFAULT;
/* Initialize range to track CPU page table updates. */
spin_lock_irqsave(&hmm->ranges_lock, flags);
range->hmm = hmm;
- kref_get(&hmm->kref);
list_add(&range->list, &hmm->ranges);
/*
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
/* Drop reference taken by hmm_range_register() */
- mmput(hmm->mm);
- hmm_put(hmm);
+ mmput(hmm->mmu_notifier.mm);
/*
* The range is now invalid and the ref on the hmm is dropped, so
struct mm_walk mm_walk;
int ret;
- lockdep_assert_held(&hmm->mm->mmap_sem);
+ lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem);
do {
/* If range is no longer valid force retry. */
if (!range->valid)
return -EBUSY;
- vma = find_vma(hmm->mm, start);
+ vma = find_vma(hmm->mmu_notifier.mm, start);
if (vma == NULL || (vma->vm_flags & device_vma))
return -EFAULT;
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