drm/msm: shrinker support

For a first step, only purge obj->madv==DONTNEED objects.  We could be
more agressive and next try unpinning inactive objects..  but that is
only useful if you have swap.
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/Makefile

@@ -46,6 +46,7 @@ msm-y := \
 	msm_fence.o \
 	msm_gem.o \
 	msm_gem_prime.o \
+	msm_gem_shrinker.o \
 	msm_gem_submit.o \
 	msm_gpu.o \
 	msm_iommu.o \

drivers/gpu/drm/msm/msm_drv.c

@@ -195,6 +195,8 @@ static int msm_drm_uninit(struct device *dev)
 		kfree(vbl_ev);
 	}
 
+	msm_gem_shrinker_cleanup(ddev);
+
 	drm_kms_helper_poll_fini(ddev);
 
 	drm_dev_unregister(ddev);
@@ -350,6 +352,7 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	}
 
 	ddev->dev_private = priv;
+	priv->dev = ddev;
 
 	ret = msm_mdss_init(ddev);
 	if (ret) {
@@ -382,6 +385,8 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	if (ret)
 		goto fail;
 
+	msm_gem_shrinker_init(ddev);
+
 	switch (get_mdp_ver(pdev)) {
 	case 4:
 		kms = mdp4_kms_init(ddev);

drivers/gpu/drm/msm/msm_drv.h

@@ -78,6 +78,8 @@ struct msm_vblank_ctrl {
 
 struct msm_drm_private {
 
+	struct drm_device *dev;
+
 	struct msm_kms *kms;
 
 	/* subordinate devices, if present: */
@@ -151,6 +153,8 @@ struct msm_drm_private {
 		struct drm_mm mm;
 	} vram;
 
+	struct shrinker shrinker;
+
 	struct msm_vblank_ctrl vblank_ctrl;
 };
 
@@ -169,6 +173,9 @@ void msm_gem_submit_free(struct msm_gem_submit *submit);
 int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		struct drm_file *file);
 
+void msm_gem_shrinker_init(struct drm_device *dev);
+void msm_gem_shrinker_cleanup(struct drm_device *dev);
+
 int msm_gem_mmap_obj(struct drm_gem_object *obj,
 			struct vm_area_struct *vma);
 int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
@@ -196,6 +203,7 @@ void msm_gem_prime_unpin(struct drm_gem_object *obj);
 void *msm_gem_vaddr_locked(struct drm_gem_object *obj);
 void *msm_gem_vaddr(struct drm_gem_object *obj);
 int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv);
+void msm_gem_purge(struct drm_gem_object *obj);
 int msm_gem_sync_object(struct drm_gem_object *obj,
 		struct msm_fence_context *fctx, bool exclusive);
 void msm_gem_move_to_active(struct drm_gem_object *obj,

drivers/gpu/drm/msm/msm_gem.c

@@ -448,6 +448,38 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv)
 	return (msm_obj->madv != __MSM_MADV_PURGED);
 }
 
+void msm_gem_purge(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+
+	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
+	WARN_ON(!is_purgeable(msm_obj));
+	WARN_ON(obj->import_attach);
+
+	put_iova(obj);
+
+	vunmap(msm_obj->vaddr);
+	msm_obj->vaddr = NULL;
+
+	put_pages(obj);
+
+	msm_obj->madv = __MSM_MADV_PURGED;
+
+	drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
+	drm_gem_free_mmap_offset(obj);
+
+	/* Our goal here is to return as much of the memory as
+	 * is possible back to the system as we are called from OOM.
+	 * To do this we must instruct the shmfs to drop all of its
+	 * backing pages, *now*.
+	 */
+	shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
+
+	invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,
+			0, (loff_t)-1);
+}
+
 /* must be called before _move_to_active().. */
 int msm_gem_sync_object(struct drm_gem_object *obj,
 		struct msm_fence_context *fctx, bool exclusive)

drivers/gpu/drm/msm/msm_gem.h

@@ -77,6 +77,12 @@ static inline bool is_active(struct msm_gem_object *msm_obj)
 	return msm_obj->gpu != NULL;
 }
 
+static inline bool is_purgeable(struct msm_gem_object *msm_obj)
+{
+	return (msm_obj->madv == MSM_MADV_DONTNEED) && msm_obj->sgt &&
+			!msm_obj->base.dma_buf && !msm_obj->base.import_attach;
+}
+
 #define MAX_CMDS 4
 
 /* Created per submit-ioctl, to track bo's and cmdstream bufs, etc,

drivers/gpu/drm/msm/msm_gem_shrinker.c

+/*
+ * Copyright (C) 2016 Red Hat
+ * Author: Rob Clark <robdclark@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "msm_drv.h"
+#include "msm_gem.h"
+
+static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
+{
+	if (!mutex_is_locked(mutex))
+		return false;
+
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_MUTEXES)
+	return mutex->owner == task;
+#else
+	/* Since UP may be pre-empted, we cannot assume that we own the lock */
+	return false;
+#endif
+}
+
+static bool msm_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
+{
+	if (!mutex_trylock(&dev->struct_mutex)) {
+		if (!mutex_is_locked_by(&dev->struct_mutex, current))
+			return false;
+		*unlock = false;
+	} else {
+		*unlock = true;
+	}
+
+	return true;
+}
+
+
+static unsigned long
+msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
+{
+	struct msm_drm_private *priv =
+		container_of(shrinker, struct msm_drm_private, shrinker);
+	struct drm_device *dev = priv->dev;
+	struct msm_gem_object *msm_obj;
+	unsigned long count = 0;
+	bool unlock;
+
+	if (!msm_gem_shrinker_lock(dev, &unlock))
+		return 0;
+
+	list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {
+		if (is_purgeable(msm_obj))
+			count += msm_obj->base.size >> PAGE_SHIFT;
+	}
+
+	if (unlock)
+		mutex_unlock(&dev->struct_mutex);
+
+	return count;
+}
+
+static unsigned long
+msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
+{
+	struct msm_drm_private *priv =
+		container_of(shrinker, struct msm_drm_private, shrinker);
+	struct drm_device *dev = priv->dev;
+	struct msm_gem_object *msm_obj;
+	unsigned long freed = 0;
+	bool unlock;
+
+	if (!msm_gem_shrinker_lock(dev, &unlock))
+		return SHRINK_STOP;
+
+	list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) {
+		if (freed >= sc->nr_to_scan)
+			break;
+		if (is_purgeable(msm_obj)) {
+			msm_gem_purge(&msm_obj->base);
+			freed += msm_obj->base.size >> PAGE_SHIFT;
+		}
+	}
+
+	if (unlock)
+		mutex_unlock(&dev->struct_mutex);
+
+	if (freed > 0)
+		pr_info_ratelimited("Purging %lu bytes\n", freed << PAGE_SHIFT);
+
+	return freed;
+}
+
+/**
+ * msm_gem_shrinker_init - Initialize msm shrinker
+ * @dev_priv: msm device
+ *
+ * This function registers and sets up the msm shrinker.
+ */
+void msm_gem_shrinker_init(struct drm_device *dev)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	priv->shrinker.count_objects = msm_gem_shrinker_count;
+	priv->shrinker.scan_objects = msm_gem_shrinker_scan;
+	priv->shrinker.seeks = DEFAULT_SEEKS;
+	WARN_ON(register_shrinker(&priv->shrinker));
+}
+
+/**
+ * msm_gem_shrinker_cleanup - Clean up msm shrinker
+ * @dev_priv: msm device
+ *
+ * This function unregisters the msm shrinker.
+ */
+void msm_gem_shrinker_cleanup(struct drm_device *dev)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	unregister_shrinker(&priv->shrinker);
+}