[PATCH 07/11] drm/i915: Add support for stealing purgable stolen pages

[ankitprasad.r.sharma@intel.com]

From: Chris Wilson <chris at chris-wilson.co.uk>

If we run out of stolen memory when trying to allocate an object, see if
we can reap enough purgeable objects to free up enough contiguous free
space for the allocation. This is in principle very much like evicting
objects to free up enough contiguous space in the vma when binding
a new object - and you will be forgiven for thinking that the code looks
very similar.

At the moment, we do not allow userspace to allocate objects in stolen,
so there is neither the memory pressure to trigger stolen eviction nor
any purgeable objects inside the stolen arena. However, this will change
in the near future, and so better management and defragmentation of
stolen memory will become a real issue.

v2: Remember to remove the drm_mm_node.

v3: Rebased to the latest drm-intel-nightly (Ankit)

v4: corrected if-else braces format (Tvrtko/kerneldoc)

v5: Rebased to the latest drm-intel-nightly (Ankit)
Added a seperate list to maintain purgable objects from stolen memory
region (Chris/Daniel)

v6: Compiler optimization (merging 2 single loops into one for() loop),
corrected code for object eviction, retire_requests before starting
object eviction (Chris)

v7: Added kernel doc for i915_gem_object_create_stolen()

v8: Check for struct_mutex lock before creating object from stolen
region (Tvrtko)

v9: Renamed variables to make usage clear, added comment, removed onetime
used macro (Tvrtko)

v10: Avoid masking of error when stolen_alloc fails (Tvrtko)

v11: Renamed stolen_link to tmp_link, as it may be used for other
purposes too (Chris)
Used ERR_CAST to cast error pointers while returning

v12: Added lockdep_assert before starting stolen-backed object
eviction (Chris)

v13: Rebased

Testcase: igt/gem_stolen

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c    |   6 +-
 drivers/gpu/drm/i915/i915_drv.h        |  17 +++-
 drivers/gpu/drm/i915/i915_gem.c        |  15 +++
 drivers/gpu/drm/i915/i915_gem_stolen.c | 171 +++++++++++++++++++++++++++++----
 drivers/gpu/drm/i915/intel_pm.c        |   4 +-
 5 files changed, 188 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index e4f2c55..e5b4274 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -182,7 +182,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
 		seq_puts(m, ")");
 	}
 	if (obj->stolen)
-		seq_printf(m, " (stolen: %08llx)", obj->stolen->start);
+		seq_printf(m, " (stolen: %08llx)", obj->stolen->base.start);
 	if (obj->pin_display || obj->fault_mappable) {
 		char s[3], *t = s;
 		if (obj->pin_display)
@@ -254,9 +254,9 @@ static int obj_rank_by_stolen(void *priv,
 	struct drm_i915_gem_object *b =
 		container_of(B, struct drm_i915_gem_object, obj_exec_link);
 
-	if (a->stolen->start < b->stolen->start)
+	if (a->stolen->base.start < b->stolen->base.start)
 		return -1;
-	if (a->stolen->start > b->stolen->start)
+	if (a->stolen->base.start > b->stolen->base.start)
 		return 1;
 	return 0;
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5245a65..94bd79f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -831,6 +831,12 @@ struct i915_ctx_hang_stats {
 	bool banned;
 };
 
+struct i915_stolen_node {
+	struct drm_mm_node base;
+	struct list_head mm_link;
+	struct drm_i915_gem_object *obj;
+};
+
 /* This must match up with the value previously used for execbuf2.rsvd1. */
 #define DEFAULT_CONTEXT_HANDLE 0
 
@@ -1281,6 +1287,13 @@ struct i915_gem_mm {
 	 */
 	struct list_head unbound_list;
 
+	/**
+	 * List of stolen objects that have been marked as purgeable and
+	 * thus available for reaping if we need more space for a new
+	 * allocation. Ordered by time of marking purgeable.
+	 */
+	struct list_head stolen_list;
+
 	/** Usable portion of the GTT for GEM */
 	unsigned long stolen_base; /* limited to low memory (32-bit) */
 
@@ -2134,7 +2147,7 @@ struct drm_i915_gem_object {
 	struct list_head vma_list;
 
 	/** Stolen memory for this object, instead of being backed by shmem. */
-	struct drm_mm_node *stolen;
+	struct i915_stolen_node *stolen;
 	struct list_head global_list;
 
 	struct list_head engine_list[I915_NUM_ENGINES];
@@ -2142,6 +2155,8 @@ struct drm_i915_gem_object {
 	struct list_head obj_exec_link;
 
 	struct list_head batch_pool_link;
+	/** Used to link an object to a list temporarily */
+	struct list_head tmp_link;
 
 	/**
 	 * This is set if the object is on the active lists (has pending
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 52181fe..5f5a81b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4593,6 +4593,20 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
 	if (obj->madv == I915_MADV_DONTNEED && obj->pages == NULL)
 		i915_gem_object_truncate(obj);
 
+	if (obj->stolen) {
+		switch (obj->madv) {
+		case I915_MADV_WILLNEED:
+			list_del_init(&obj->stolen->mm_link);
+			break;
+		case I915_MADV_DONTNEED:
+			list_move(&obj->stolen->mm_link,
+				  &dev_priv->mm.stolen_list);
+			break;
+		default:
+			break;
+		}
+	}
+
 	args->retained = obj->madv != __I915_MADV_PURGED;
 
 out:
@@ -5154,6 +5168,7 @@ i915_gem_load_init(struct drm_device *dev)
 	INIT_LIST_HEAD(&dev_priv->context_list);
 	INIT_LIST_HEAD(&dev_priv->mm.unbound_list);
 	INIT_LIST_HEAD(&dev_priv->mm.bound_list);
+	INIT_LIST_HEAD(&dev_priv->mm.stolen_list);
 	INIT_LIST_HEAD(&dev_priv->mm.fence_list);
 	for (i = 0; i < I915_NUM_ENGINES; i++)
 		init_engine_lists(&dev_priv->engine[i]);
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index dcb70c1..1b1b9c1 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -553,7 +553,8 @@ i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
 	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
 
 	if (obj->stolen) {
-		i915_gem_stolen_remove_node(dev_priv, obj->stolen);
+		list_del(&obj->stolen->mm_link);
+		i915_gem_stolen_remove_node(dev_priv, &obj->stolen->base);
 		kfree(obj->stolen);
 		obj->stolen = NULL;
 	}
@@ -566,7 +567,7 @@ static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
 
 static struct drm_i915_gem_object *
 _i915_gem_object_create_stolen(struct drm_device *dev,
-			       struct drm_mm_node *stolen)
+			       struct i915_stolen_node *stolen)
 {
 	struct drm_i915_gem_object *obj;
 	struct sg_table *pages;
@@ -575,11 +576,12 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
 	if (obj == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	drm_gem_private_object_init(dev, &obj->base, stolen->size);
+	drm_gem_private_object_init(dev, &obj->base, stolen->base.size);
 	i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
 
 	pages = i915_pages_create_for_stolen(dev,
-					     stolen->start, stolen->size);
+					     stolen->base.start,
+					     stolen->base.size);
 	if (IS_ERR(pages)) {
 		i915_gem_object_free(obj);
 		return ERR_CAST(pages);
@@ -593,24 +595,112 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
 	i915_gem_object_pin_pages(obj);
 	obj->stolen = stolen;
 
+	stolen->obj = obj;
+	INIT_LIST_HEAD(&stolen->mm_link);
+
 	obj->base.read_domains = I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT;
 	obj->cache_level = HAS_LLC(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
 
 	return obj;
 }
 
-struct drm_i915_gem_object *
-i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
+static bool
+mark_free(struct drm_i915_gem_object *obj, struct list_head *unwind)
+{
+	BUG_ON(obj->stolen == NULL);
+
+	if (obj->madv != I915_MADV_DONTNEED)
+		return false;
+
+	if (obj->pin_display)
+		return false;
+
+	list_add(&obj->tmp_link, unwind);
+	return drm_mm_scan_add_block(&obj->stolen->base);
+}
+
+static int
+stolen_evict(struct drm_i915_private *dev_priv, u64 size)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
-	struct drm_mm_node *stolen;
-	int ret;
+	struct list_head unwind, evict;
+	struct i915_stolen_node *iter;
+	int ret, active;
 
-	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return ERR_PTR(-ENODEV);
+	lockdep_assert_held(&dev_priv->dev->struct_mutex);
+	drm_mm_init_scan(&dev_priv->mm.stolen, size, 0, 0);
+	INIT_LIST_HEAD(&unwind);
+
+	/* Retire all requests before creating the evict list */
+	i915_gem_retire_requests(dev_priv);
+
+	for (active = 0; active <= 1; active++) {
+		list_for_each_entry(iter, &dev_priv->mm.stolen_list, mm_link) {
+			if (iter->obj->active != active)
+				continue;
+
+			if (mark_free(iter->obj, &unwind))
+				goto found;
+		}
+	}
+
+found:
+	INIT_LIST_HEAD(&evict);
+	while (!list_empty(&unwind)) {
+		obj = list_first_entry(&unwind,
+				       struct drm_i915_gem_object,
+				       tmp_link);
+		list_del(&obj->tmp_link);
+
+		if (drm_mm_scan_remove_block(&obj->stolen->base)) {
+			list_add(&obj->tmp_link, &evict);
+			drm_gem_object_reference(&obj->base);
+		}
+	}
+
+	ret = 0;
+	while (!list_empty(&evict)) {
+		obj = list_first_entry(&evict,
+				       struct drm_i915_gem_object,
+				       tmp_link);
+		list_del(&obj->tmp_link);
+
+		if (ret == 0) {
+			struct i915_vma *vma, *vma_next;
+
+			list_for_each_entry_safe(vma, vma_next,
+						 &obj->vma_list,
+						 obj_link)
+				if (i915_vma_unbind(vma))
+					break;
+
+			/* Stolen pins its pages to prevent the
+			 * normal shrinker from processing stolen
+			 * objects.
+			 */
+			i915_gem_object_unpin_pages(obj);
+
+			ret = i915_gem_object_put_pages(obj);
+			if (ret == 0) {
+				i915_gem_object_release_stolen(obj);
+				obj->madv = __I915_MADV_PURGED;
+			} else {
+				i915_gem_object_pin_pages(obj);
+			}
+		}
+
+		drm_gem_object_unreference(&obj->base);
+	}
+
+	return ret;
+}
+
+static struct i915_stolen_node *
+stolen_alloc(struct drm_i915_private *dev_priv, u64 size)
+{
+	struct i915_stolen_node *stolen;
+	int ret;
 
-	DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
 	if (size == 0)
 		return ERR_PTR(-EINVAL);
 
@@ -618,17 +708,60 @@ i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
 	if (!stolen)
 		return ERR_PTR(-ENOMEM);
 
-	ret = i915_gem_stolen_insert_node(dev_priv, stolen, size, 4096);
+	ret = i915_gem_stolen_insert_node(dev_priv, &stolen->base, size, 4096);
+	if (ret == 0)
+		goto out;
+
+	/* No more stolen memory available, or too fragmented.
+	 * Try evicting purgeable objects and search again.
+	 */
+	ret = stolen_evict(dev_priv, size);
+	if (ret == 0)
+		ret = i915_gem_stolen_insert_node(dev_priv, &stolen->base,
+						  size, 4096);
+out:
 	if (ret) {
 		kfree(stolen);
 		return ERR_PTR(ret);
 	}
 
+	return stolen;
+}
+
+/**
+ * i915_gem_object_create_stolen() - creates object using the stolen memory
+ * @dev:	drm device
+ * @size:	size of the object requested
+ *
+ * i915_gem_object_create_stolen() tries to allocate memory for the object
+ * from the stolen memory region. If not enough memory is found, it tries
+ * evicting purgeable objects and searching again.
+ *
+ * Returns: Object pointer - success and error pointer - failure
+ */
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj;
+	struct i915_stolen_node *stolen;
+
+	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
+
+	if (!drm_mm_initialized(&dev_priv->mm.stolen))
+		return ERR_PTR(-ENODEV);
+
+	DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
+
+	stolen = stolen_alloc(dev_priv, size);
+	if (IS_ERR(stolen))
+		return ERR_CAST(stolen);
+
 	obj = _i915_gem_object_create_stolen(dev, stolen);
 	if (!IS_ERR(obj))
 		return obj;
 
-	i915_gem_stolen_remove_node(dev_priv, stolen);
+	i915_gem_stolen_remove_node(dev_priv, &stolen->base);
 	kfree(stolen);
 	return obj;
 }
@@ -642,7 +775,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 	struct drm_i915_gem_object *obj;
-	struct drm_mm_node *stolen;
+	struct i915_stolen_node *stolen;
 	struct i915_vma *vma;
 	int ret;
 
@@ -663,10 +796,10 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	if (!stolen)
 		return ERR_PTR(-ENOMEM);
 
-	stolen->start = stolen_offset;
-	stolen->size = size;
+	stolen->base.start = stolen_offset;
+	stolen->base.size = size;
 	mutex_lock(&dev_priv->mm.stolen_lock);
-	ret = drm_mm_reserve_node(&dev_priv->mm.stolen, stolen);
+	ret = drm_mm_reserve_node(&dev_priv->mm.stolen, &stolen->base);
 	mutex_unlock(&dev_priv->mm.stolen_lock);
 	if (ret) {
 		DRM_DEBUG_KMS("failed to allocate stolen space\n");
@@ -677,7 +810,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	obj = _i915_gem_object_create_stolen(dev, stolen);
 	if (IS_ERR(obj)) {
 		DRM_DEBUG_KMS("failed to allocate stolen object\n");
-		i915_gem_stolen_remove_node(dev_priv, stolen);
+		i915_gem_stolen_remove_node(dev_priv, &stolen->base);
 		kfree(stolen);
 		return obj;
 	}
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 321bffd..e1ee71a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5580,7 +5580,7 @@ static void valleyview_check_pctx(struct drm_i915_private *dev_priv)
 	unsigned long pctx_addr = I915_READ(VLV_PCBR) & ~4095;
 
 	WARN_ON(pctx_addr != dev_priv->mm.stolen_base +
-			     dev_priv->vlv_pctx->stolen->start);
+			     dev_priv->vlv_pctx->stolen->base.start);
 }
 
 
@@ -5653,7 +5653,7 @@ static void valleyview_setup_pctx(struct drm_i915_private *dev_priv)
 		goto out;
 	}
 
-	pctx_paddr = dev_priv->mm.stolen_base + pctx->stolen->start;
+	pctx_paddr = dev_priv->mm.stolen_base + pctx->stolen->base.start;
 	I915_WRITE(VLV_PCBR, pctx_paddr);
 
 out:
-- 
1.9.1

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