1 files changed, 230 insertions, 179 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index fe69fc837d9e..d38413997379 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -32,6 +32,15 @@
 #include <linux/mempolicy.h>
 #include <linux/swap.h>
 
+struct i915_mm_struct {
+        struct mm_struct *mm;
+        struct drm_device *dev;
+        struct i915_mmu_notifier *mn;
+        struct hlist_node node;
+        struct kref kref;
+        struct work_struct work;
+};
+
 #if defined(CONFIG_MMU_NOTIFIER)
 #include <linux/interval_tree.h>
 
@@ -41,16 +50,12 @@ struct i915_mmu_notifier {
         struct mmu_notifier mn;
         struct rb_root objects;
         struct list_head linear;
-        struct drm_device *dev;
-        struct mm_struct *mm;
-        struct work_struct work;
-        unsigned long count;
         unsigned long serial;
         bool has_linear;
 };
 
 struct i915_mmu_object {
-        struct i915_mmu_notifier *mmu;
+        struct i915_mmu_notifier *mn;
         struct interval_tree_node it;
         struct list_head link;
         struct drm_i915_gem_object *obj;
@@ -96,18 +101,18 @@ static void *invalidate_range__linear(struct i915_mmu_notifier *mn,
                                       unsigned long start,
                                       unsigned long end)
 {
-        struct i915_mmu_object *mmu;
+        struct i915_mmu_object *mo;
         unsigned long serial;
 
 restart:
         serial = mn->serial;
-        list_for_each_entry(mmu, &mn->linear, link) {
+        list_for_each_entry(mo, &mn->linear, link) {
                 struct drm_i915_gem_object *obj;
 
-                if (mmu->it.last < start || mmu->it.start > end)
+                if (mo->it.last < start || mo->it.start > end)
                         continue;
 
-                obj = mmu->obj;
+                obj = mo->obj;
                 drm_gem_object_reference(&obj->base);
                 spin_unlock(&mn->lock);
 
@@ -160,130 +165,47 @@ static const struct mmu_notifier_ops i915_gem_userptr_notifier = {
 };
 
 static struct i915_mmu_notifier *
-__i915_mmu_notifier_lookup(struct drm_device *dev, struct mm_struct *mm)
-{
-        struct drm_i915_private *dev_priv = to_i915(dev);
-        struct i915_mmu_notifier *mmu;
-
-        /* Protected by dev->struct_mutex */
-        hash_for_each_possible(dev_priv->mmu_notifiers, mmu, node, (unsigned long)mm)
-                if (mmu->mm == mm)
-                        return mmu;
-
-        return NULL;
-}
-
-static struct i915_mmu_notifier *
-i915_mmu_notifier_get(struct drm_device *dev, struct mm_struct *mm)
+i915_mmu_notifier_create(struct mm_struct *mm)
 {
-        struct drm_i915_private *dev_priv = to_i915(dev);
-        struct i915_mmu_notifier *mmu;
+        struct i915_mmu_notifier *mn;
         int ret;
 
-        lockdep_assert_held(&dev->struct_mutex);
-
-        mmu = __i915_mmu_notifier_lookup(dev, mm);
-        if (mmu)
-                return mmu;
-
-        mmu = kmalloc(sizeof(*mmu), GFP_KERNEL);
-        if (mmu == NULL)
+        mn = kmalloc(sizeof(*mn), GFP_KERNEL);
+        if (mn == NULL)
                 return ERR_PTR(-ENOMEM);
 
-        spin_lock_init(&mmu->lock);
-        mmu->dev = dev;
-        mmu->mn.ops = &i915_gem_userptr_notifier;
-        mmu->mm = mm;
-        mmu->objects = RB_ROOT;
-        mmu->count = 0;
-        mmu->serial = 1;
-        INIT_LIST_HEAD(&mmu->linear);
-        mmu->has_linear = false;
-
-        /* Protected by mmap_sem (write-lock) */
-        ret = __mmu_notifier_register(&mmu->mn, mm);
+        spin_lock_init(&mn->lock);
+        mn->mn.ops = &i915_gem_userptr_notifier;
+        mn->objects = RB_ROOT;
+        mn->serial = 1;
+        INIT_LIST_HEAD(&mn->linear);
+        mn->has_linear = false;
+
+         /* Protected by mmap_sem (write-lock) */
+        ret = __mmu_notifier_register(&mn->mn, mm);
         if (ret) {
-                kfree(mmu);
+                kfree(mn);
                 return ERR_PTR(ret);
         }
 
-        /* Protected by dev->struct_mutex */
-        hash_add(dev_priv->mmu_notifiers, &mmu->node, (unsigned long)mm);
-        return mmu;
+        return mn;
 }
 
-static void
-__i915_mmu_notifier_destroy_worker(struct work_struct *work)
+static void __i915_mmu_notifier_update_serial(struct i915_mmu_notifier *mn)
 {
-        struct i915_mmu_notifier *mmu = container_of(work, typeof(*mmu), work);
-        mmu_notifier_unregister(&mmu->mn, mmu->mm);
-        kfree(mmu);
-}
-
-static void
-__i915_mmu_notifier_destroy(struct i915_mmu_notifier *mmu)
-{
-        lockdep_assert_held(&mmu->dev->struct_mutex);
-
-        /* Protected by dev->struct_mutex */
-        hash_del(&mmu->node);
-
-        /* Our lock ordering is: mmap_sem, mmu_notifier_scru, struct_mutex.
-         * We enter the function holding struct_mutex, therefore we need
-         * to drop our mutex prior to calling mmu_notifier_unregister in
-         * order to prevent lock inversion (and system-wide deadlock)
-         * between the mmap_sem and struct-mutex. Hence we defer the
-         * unregistration to a workqueue where we hold no locks.
-         */
-        INIT_WORK(&mmu->work, __i915_mmu_notifier_destroy_worker);
-        schedule_work(&mmu->work);
-}
-
-static void __i915_mmu_notifier_update_serial(struct i915_mmu_notifier *mmu)
-{
-        if (++mmu->serial == 0)
-                mmu->serial = 1;
-}
-
-static bool i915_mmu_notifier_has_linear(struct i915_mmu_notifier *mmu)
-{
-        struct i915_mmu_object *mn;
-
-        list_for_each_entry(mn, &mmu->linear, link)
-                if (mn->is_linear)
-                        return true;
-
-        return false;
-}
-
-static void
-i915_mmu_notifier_del(struct i915_mmu_notifier *mmu,
-                      struct i915_mmu_object *mn)
-{
-        lockdep_assert_held(&mmu->dev->struct_mutex);
-
-        spin_lock(&mmu->lock);
-        list_del(&mn->link);
-        if (mn->is_linear)
-                mmu->has_linear = i915_mmu_notifier_has_linear(mmu);
-        else
-                interval_tree_remove(&mn->it, &mmu->objects);
-        __i915_mmu_notifier_update_serial(mmu);
-        spin_unlock(&mmu->lock);
-
-        /* Protected against _add() by dev->struct_mutex */
-        if (--mmu->count == 0)
-                __i915_mmu_notifier_destroy(mmu);
+        if (++mn->serial == 0)
+                mn->serial = 1;
 }
 
 static int
-i915_mmu_notifier_add(struct i915_mmu_notifier *mmu,
-                      struct i915_mmu_object *mn)
+i915_mmu_notifier_add(struct drm_device *dev,
+                      struct i915_mmu_notifier *mn,
+                      struct i915_mmu_object *mo)
 {
         struct interval_tree_node *it;
         int ret;
 
-        ret = i915_mutex_lock_interruptible(mmu->dev);
+        ret = i915_mutex_lock_interruptible(dev);
         if (ret)
                 return ret;
 
@@ -291,11 +213,11 @@ i915_mmu_notifier_add(struct i915_mmu_notifier *mmu,
          * remove the objects from the interval tree) before we do
          * the check for overlapping objects.
          */
-        i915_gem_retire_requests(mmu->dev);
+        i915_gem_retire_requests(dev);
 
-        spin_lock(&mmu->lock);
-        it = interval_tree_iter_first(&mmu->objects,
-                                      mn->it.start, mn->it.last);
+        spin_lock(&mn->lock);
+        it = interval_tree_iter_first(&mn->objects,
+                                      mo->it.start, mo->it.last);
         if (it) {
                 struct drm_i915_gem_object *obj;
 
@@ -312,86 +234,122 @@ i915_mmu_notifier_add(struct i915_mmu_notifier *mmu,
 
                 obj = container_of(it, struct i915_mmu_object, it)->obj;
                 if (!obj->userptr.workers)
-                        mmu->has_linear = mn->is_linear = true;
+                        mn->has_linear = mo->is_linear = true;
                 else
                         ret = -EAGAIN;
         } else
-                interval_tree_insert(&mn->it, &mmu->objects);
+                interval_tree_insert(&mo->it, &mn->objects);
 
         if (ret == 0) {
-                list_add(&mn->link, &mmu->linear);
-                __i915_mmu_notifier_update_serial(mmu);
+                list_add(&mo->link, &mn->linear);
+                __i915_mmu_notifier_update_serial(mn);
         }
-        spin_unlock(&mmu->lock);
-        mutex_unlock(&mmu->dev->struct_mutex);
+        spin_unlock(&mn->lock);
+        mutex_unlock(&dev->struct_mutex);
 
         return ret;
 }
 
+static bool i915_mmu_notifier_has_linear(struct i915_mmu_notifier *mn)
+{
+        struct i915_mmu_object *mo;
+
+        list_for_each_entry(mo, &mn->linear, link)
+                if (mo->is_linear)
+                        return true;
+
+        return false;
+}
+
+static void
+i915_mmu_notifier_del(struct i915_mmu_notifier *mn,
+                      struct i915_mmu_object *mo)
+{
+        spin_lock(&mn->lock);
+        list_del(&mo->link);
+        if (mo->is_linear)
+                mn->has_linear = i915_mmu_notifier_has_linear(mn);
+        else
+                interval_tree_remove(&mo->it, &mn->objects);
+        __i915_mmu_notifier_update_serial(mn);
+        spin_unlock(&mn->lock);
+}
+
 static void
 i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj)
 {
-        struct i915_mmu_object *mn;
+        struct i915_mmu_object *mo;
 
-        mn = obj->userptr.mn;
-        if (mn == NULL)
+        mo = obj->userptr.mmu_object;
+        if (mo == NULL)
                 return;
 
-        i915_mmu_notifier_del(mn->mmu, mn);
-        obj->userptr.mn = NULL;
+        i915_mmu_notifier_del(mo->mn, mo);
+        kfree(mo);
+
+        obj->userptr.mmu_object = NULL;
+}
+
+static struct i915_mmu_notifier *
+i915_mmu_notifier_find(struct i915_mm_struct *mm)
+{
+        if (mm->mn == NULL) {
+                down_write(&mm->mm->mmap_sem);
+                mutex_lock(&to_i915(mm->dev)->mm_lock);
+                if (mm->mn == NULL)
+                        mm->mn = i915_mmu_notifier_create(mm->mm);
+                mutex_unlock(&to_i915(mm->dev)->mm_lock);
+                up_write(&mm->mm->mmap_sem);
+        }
+        return mm->mn;
 }
 
 static int
 i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
                                     unsigned flags)
 {
-        struct i915_mmu_notifier *mmu;
-        struct i915_mmu_object *mn;
+        struct i915_mmu_notifier *mn;
+        struct i915_mmu_object *mo;
         int ret;
 
         if (flags & I915_USERPTR_UNSYNCHRONIZED)
                 return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;
 
-        down_write(&obj->userptr.mm->mmap_sem);
-        ret = i915_mutex_lock_interruptible(obj->base.dev);
-        if (ret == 0) {
-                mmu = i915_mmu_notifier_get(obj->base.dev, obj->userptr.mm);
-                if (!IS_ERR(mmu))
-                        mmu->count++; /* preemptive add to act as a refcount */
-                else
-                        ret = PTR_ERR(mmu);
-                mutex_unlock(&obj->base.dev->struct_mutex);
-        }
-        up_write(&obj->userptr.mm->mmap_sem);
-        if (ret)
-                return ret;
+        if (WARN_ON(obj->userptr.mm == NULL))
+                return -EINVAL;
 
-        mn = kzalloc(sizeof(*mn), GFP_KERNEL);
-        if (mn == NULL) {
-                ret = -ENOMEM;
-                goto destroy_mmu;
-        }
+        mn = i915_mmu_notifier_find(obj->userptr.mm);
+        if (IS_ERR(mn))
+                return PTR_ERR(mn);
 
-        mn->mmu = mmu;
-        mn->it.start = obj->userptr.ptr;
-        mn->it.last = mn->it.start + obj->base.size - 1;
-        mn->obj = obj;
+        mo = kzalloc(sizeof(*mo), GFP_KERNEL);
+        if (mo == NULL)
+                return -ENOMEM;
 
-        ret = i915_mmu_notifier_add(mmu, mn);
-        if (ret)
-                goto free_mn;
+        mo->mn = mn;
+        mo->it.start = obj->userptr.ptr;
+        mo->it.last = mo->it.start + obj->base.size - 1;
+        mo->obj = obj;
 
-        obj->userptr.mn = mn;
+        ret = i915_mmu_notifier_add(obj->base.dev, mn, mo);
+        if (ret) {
+                kfree(mo);
+                return ret;
+        }
+
+        obj->userptr.mmu_object = mo;
         return 0;
+}
+
+static void
+i915_mmu_notifier_free(struct i915_mmu_notifier *mn,
+                       struct mm_struct *mm)
+{
+        if (mn == NULL)
+                return;
 
-free_mn:
+        mmu_notifier_unregister(&mn->mn, mm);
         kfree(mn);
-destroy_mmu:
-        mutex_lock(&obj->base.dev->struct_mutex);
-        if (--mmu->count == 0)
-                __i915_mmu_notifier_destroy(mmu);
-        mutex_unlock(&obj->base.dev->struct_mutex);
-        return ret;
 }
 
 #else
@@ -413,15 +371,114 @@ i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
 
         return 0;
 }
+
+static void
+i915_mmu_notifier_free(struct i915_mmu_notifier *mn,
+                       struct mm_struct *mm)
+{
+}
+
 #endif
 
+static struct i915_mm_struct *
+__i915_mm_struct_find(struct drm_i915_private *dev_priv, struct mm_struct *real)
+{
+        struct i915_mm_struct *mm;
+
+        /* Protected by dev_priv->mm_lock */
+        hash_for_each_possible(dev_priv->mm_structs, mm, node, (unsigned long)real)
+                if (mm->mm == real)
+                        return mm;
+
+        return NULL;
+}
+
+static int
+i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj)
+{
+        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
+        struct i915_mm_struct *mm;
+        int ret = 0;
+
+        /* During release of the GEM object we hold the struct_mutex. This
+         * precludes us from calling mmput() at that time as that may be
+         * the last reference and so call exit_mmap(). exit_mmap() will
+         * attempt to reap the vma, and if we were holding a GTT mmap
+         * would then call drm_gem_vm_close() and attempt to reacquire
+         * the struct mutex. So in order to avoid that recursion, we have
+         * to defer releasing the mm reference until after we drop the
+         * struct_mutex, i.e. we need to schedule a worker to do the clean
+         * up.
+         */
+        mutex_lock(&dev_priv->mm_lock);
+        mm = __i915_mm_struct_find(dev_priv, current->mm);
+        if (mm == NULL) {
+                mm = kmalloc(sizeof(*mm), GFP_KERNEL);
+                if (mm == NULL) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+
+                kref_init(&mm->kref);
+                mm->dev = obj->base.dev;
+
+                mm->mm = current->mm;
+                atomic_inc(&current->mm->mm_count);
+
+                mm->mn = NULL;
+
+                /* Protected by dev_priv->mm_lock */
+                hash_add(dev_priv->mm_structs,
+                         &mm->node, (unsigned long)mm->mm);
+        } else
+                kref_get(&mm->kref);
+
+        obj->userptr.mm = mm;
+out:
+        mutex_unlock(&dev_priv->mm_lock);
+        return ret;
+}
+
+static void
+__i915_mm_struct_free__worker(struct work_struct *work)
+{
+        struct i915_mm_struct *mm = container_of(work, typeof(*mm), work);
+        i915_mmu_notifier_free(mm->mn, mm->mm);
+        mmdrop(mm->mm);
+        kfree(mm);
+}
+
+static void
+__i915_mm_struct_free(struct kref *kref)
+{
+        struct i915_mm_struct *mm = container_of(kref, typeof(*mm), kref);
+
+        /* Protected by dev_priv->mm_lock */
+        hash_del(&mm->node);
+        mutex_unlock(&to_i915(mm->dev)->mm_lock);
+
+        INIT_WORK(&mm->work, __i915_mm_struct_free__worker);
+        schedule_work(&mm->work);
+}
+
+static void
+i915_gem_userptr_release__mm_struct(struct drm_i915_gem_object *obj)
+{
+        if (obj->userptr.mm == NULL)
+                return;
+
+        kref_put_mutex(&obj->userptr.mm->kref,
+                       __i915_mm_struct_free,
+                       &to_i915(obj->base.dev)->mm_lock);
+        obj->userptr.mm = NULL;
+}
+
 struct get_pages_work {
         struct work_struct work;
         struct drm_i915_gem_object *obj;
         struct task_struct *task;
 };
 
-
 #if IS_ENABLED(CONFIG_SWIOTLB)
 #define swiotlb_active() swiotlb_nr_tbl()
 #else
@@ -479,7 +536,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
         if (pvec == NULL)
                 pvec = drm_malloc_ab(num_pages, sizeof(struct page *));
         if (pvec != NULL) {
-                struct mm_struct *mm = obj->userptr.mm;
+                struct mm_struct *mm = obj->userptr.mm->mm;
 
                 down_read(&mm->mmap_sem);
                 while (pinned < num_pages) {
@@ -545,7 +602,7 @@ i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 
         pvec = NULL;
         pinned = 0;
-        if (obj->userptr.mm == current->mm) {
+        if (obj->userptr.mm->mm == current->mm) {
                 pvec = kmalloc(num_pages*sizeof(struct page *),
                                GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);
                 if (pvec == NULL) {
@@ -651,17 +708,13 @@ static void
 i915_gem_userptr_release(struct drm_i915_gem_object *obj)
 {
         i915_gem_userptr_release__mmu_notifier(obj);
-
-        if (obj->userptr.mm) {
-                mmput(obj->userptr.mm);
-                obj->userptr.mm = NULL;
-        }
+        i915_gem_userptr_release__mm_struct(obj);
 }
 
 static int
 i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
 {
-        if (obj->userptr.mn)
+        if (obj->userptr.mmu_object)
                 return 0;
 
         return i915_gem_userptr_init__mmu_notifier(obj, 0);
@@ -736,7 +789,6 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
                 return -ENODEV;
         }
 
-        /* Allocate the new object */
         obj = i915_gem_object_alloc(dev);
         if (obj == NULL)
                 return -ENOMEM;
@@ -754,8 +806,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
          * at binding. This means that we need to hook into the mmu_notifier
          * in order to detect if the mmu is destroyed.
          */
-        ret = -ENOMEM;
-        if ((obj->userptr.mm = get_task_mm(current)))
+        ret = i915_gem_userptr_init__mm_struct(obj);
+        if (ret == 0)
                 ret = i915_gem_userptr_init__mmu_notifier(obj, args->flags);
         if (ret == 0)
                 ret = drm_gem_handle_create(file, &obj->base, &handle);
@@ -772,9 +824,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
 int
 i915_gem_init_userptr(struct drm_device *dev)
 {
-#if defined(CONFIG_MMU_NOTIFIER)
         struct drm_i915_private *dev_priv = to_i915(dev);
-        hash_init(dev_priv->mmu_notifiers);
-#endif
+        mutex_init(&dev_priv->mm_lock);
+        hash_init(dev_priv->mm_structs);
         return 0;
 }