[RFC,v5,3/6] dmabuf: heaps: export system_heap buffers with GPU cgroup charging

Commit Message

T.J. Mercier April 20, 2022, 11:52 p.m. UTC

All DMA heaps now register a new GPU cgroup bucket upon creation, and the
system_heap now exports buffers associated with its GPU cgroup bucket for
tracking purposes.

In order to support GPU cgroup charge transfer on a dma-buf, the current
GPU cgroup information must be stored inside the dma-buf struct. For
tracked buffers, exporters include the struct gpucg and struct
gpucg_bucket pointers in the export info which can later be modified if
the charge is migrated to another cgroup.

Signed-off-by: Hridya Valsaraju <[e-mail]>
Signed-off-by: T.J. Mercier <[e-mail]>

---
v5 changes
Merge dmabuf: Use the GPU cgroup charge/uncharge APIs into this patch.

Remove all GPU cgroup code from dma-buf except what's necessary to support
charge transfer. Previously charging was done in export, but for
non-Android graphics use-cases this is not ideal since there may be a
dealy between allocation and export, during which time there is no
accounting.

Append "-heap" to gpucg_bucket names.

Charge on allocation instead of export. This should more closely mirror
non-Android use-cases where there is potentially a delay between allocation
and export.

Put the charge and uncharge code in the same file (system_heap_allocate,
system_heap_dma_buf_release) instead of splitting them between the heap and
the dma_buf_release.

Move no-op code to header file to match other files in the series.

v3 changes
Use more common dual author commit message format per John Stultz.

v2 changes
Move dma-buf cgroup charge transfer from a dma_buf_op defined by every
heap to a single dma-buf function for all heaps per Daniel Vetter and
Christian König.
---
 drivers/dma-buf/dma-buf.c           | 19 +++++++++++++
 drivers/dma-buf/dma-heap.c          | 39 +++++++++++++++++++++++++++
 drivers/dma-buf/heaps/system_heap.c | 28 +++++++++++++++++---
 include/linux/dma-buf.h             | 41 +++++++++++++++++++++++------
 include/linux/dma-heap.h            | 15 +++++++++++
 5 files changed, 130 insertions(+), 12 deletions(-)

Patch

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index df23239b04fc..bc89c44bd9b9 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -462,6 +462,24 @@  static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
  * &dma_buf_ops.
  */
 
+#ifdef CONFIG_CGROUP_GPU
+static void dma_buf_set_gpucg(struct dma_buf *dmabuf, const struct dma_buf_export_info *exp)
+{
+	dmabuf->gpucg = exp->gpucg;
+	dmabuf->gpucg_bucket = exp->gpucg_bucket;
+}
+
+void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info,
+				struct gpucg *gpucg,
+				struct gpucg_bucket *gpucg_bucket)
+{
+	exp_info->gpucg = gpucg;
+	exp_info->gpucg_bucket = gpucg_bucket;
+}
+#else
+static void dma_buf_set_gpucg(struct dma_buf *dmabuf, struct dma_buf_export_info *exp) {}
+#endif
+
 /**
  * dma_buf_export - Creates a new dma_buf, and associates an anon file
  * with this buffer, so it can be exported.
@@ -527,6 +545,7 @@  struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 	init_waitqueue_head(&dmabuf->poll);
 	dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
 	dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
+	dma_buf_set_gpucg(dmabuf, exp_info);
 
 	if (!resv) {
 		resv = (struct dma_resv *)&dmabuf[1];
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
index 8f5848aa144f..b81015548314 100644
--- a/drivers/dma-buf/dma-heap.c
+++ b/drivers/dma-buf/dma-heap.c
@@ -7,10 +7,12 @@ 
  */
 
 #include <linux/cdev.h>
+#include <linux/cgroup_gpu.h>
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/dma-buf.h>
 #include <linux/err.h>
+#include <linux/kconfig.h>
 #include <linux/xarray.h>
 #include <linux/list.h>
 #include <linux/slab.h>
@@ -21,6 +23,7 @@ 
 #include <uapi/linux/dma-heap.h>
 
 #define DEVNAME "dma_heap"
+#define HEAP_NAME_SUFFIX "-heap"
 
 #define NUM_HEAP_MINORS 128
 
@@ -31,6 +34,7 @@ 
  * @heap_devt		heap device node
  * @list		list head connecting to list of heaps
  * @heap_cdev		heap char device
+ * @gpucg_bucket	gpu cgroup bucket for memory accounting
  *
  * Represents a heap of memory from which buffers can be made.
  */
@@ -41,6 +45,9 @@  struct dma_heap {
 	dev_t heap_devt;
 	struct list_head list;
 	struct cdev heap_cdev;
+#ifdef CONFIG_CGROUP_GPU
+	struct gpucg_bucket gpucg_bucket;
+#endif
 };
 
 static LIST_HEAD(heap_list);
@@ -216,6 +223,19 @@  const char *dma_heap_get_name(struct dma_heap *heap)
 	return heap->name;
 }
 
+/**
+ * dma_heap_get_gpucg_bucket() - get struct gpucg_bucket for the heap.
+ * @heap: DMA-Heap to get the gpucg_bucket struct for.
+ *
+ * Returns:
+ * The gpucg_bucket struct for the heap. NULL if the GPU cgroup controller is
+ * not enabled.
+ */
+struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap)
+{
+	return &heap->gpucg_bucket;
+}
+
 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 {
 	struct dma_heap *heap, *h, *err_ret;
@@ -228,6 +248,12 @@  struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (IS_ENABLED(CONFIG_CGROUP_GPU) && strlen(exp_info->name) + strlen(HEAP_NAME_SUFFIX) >=
+		GPUCG_BUCKET_NAME_MAX_LEN) {
+		pr_err("dma_heap: Name is too long for GPU cgroup\n");
+		return ERR_PTR(-ENAMETOOLONG);
+	}
+
 	if (!exp_info->ops || !exp_info->ops->allocate) {
 		pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
 		return ERR_PTR(-EINVAL);
@@ -253,6 +279,19 @@  struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 	heap->ops = exp_info->ops;
 	heap->priv = exp_info->priv;
 
+	if (IS_ENABLED(CONFIG_CGROUP_GPU)) {
+		char gpucg_bucket_name[GPUCG_BUCKET_NAME_MAX_LEN];
+
+		snprintf(gpucg_bucket_name, sizeof(gpucg_bucket_name), "%s%s",
+			 exp_info->name, HEAP_NAME_SUFFIX);
+
+		ret = gpucg_register_bucket(dma_heap_get_gpucg_bucket(heap), gpucg_bucket_name);
+		if (ret < 0) {
+			err_ret = ERR_PTR(ret);
+			goto err0;
+		}
+	}
+
 	/* Find unused minor number */
 	ret = xa_alloc(&dma_heap_minors, &minor, heap,
 		       XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index fcf836ba9c1f..27f686faef00 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -297,6 +297,11 @@  static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
 	}
 	sg_free_table(table);
 	kfree(buffer);
+
+	if (dmabuf->gpucg && dmabuf->gpucg_bucket) {
+		gpucg_uncharge(dmabuf->gpucg, dmabuf->gpucg_bucket, dmabuf->size);
+		gpucg_put(dmabuf->gpucg);
+	}
 }
 
 static const struct dma_buf_ops system_heap_buf_ops = {
@@ -346,11 +351,21 @@  static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
 	struct scatterlist *sg;
 	struct list_head pages;
 	struct page *page, *tmp_page;
-	int i, ret = -ENOMEM;
+	struct gpucg *gpucg;
+	struct gpucg_bucket *gpucg_bucket;
+	int i, ret;
+
+	gpucg = gpucg_get(current);
+	gpucg_bucket = dma_heap_get_gpucg_bucket(heap);
+	ret = gpucg_charge(gpucg, gpucg_bucket, len);
+	if (ret)
+		goto put_gpucg;
 
 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
-	if (!buffer)
-		return ERR_PTR(-ENOMEM);
+	if (!buffer) {
+		ret = -ENOMEM;
+		goto uncharge_gpucg;
+	}
 
 	INIT_LIST_HEAD(&buffer->attachments);
 	mutex_init(&buffer->lock);
@@ -396,6 +411,8 @@  static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
 	exp_info.size = buffer->len;
 	exp_info.flags = fd_flags;
 	exp_info.priv = buffer;
+	dma_buf_exp_info_set_gpucg(&exp_info, gpucg, gpucg_bucket);
+
 	dmabuf = dma_buf_export(&exp_info);
 	if (IS_ERR(dmabuf)) {
 		ret = PTR_ERR(dmabuf);
@@ -414,7 +431,10 @@  static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
 	list_for_each_entry_safe(page, tmp_page, &pages, lru)
 		__free_pages(page, compound_order(page));
 	kfree(buffer);
-
+uncharge_gpucg:
+	gpucg_uncharge(gpucg, gpucg_bucket, len);
+put_gpucg:
+	gpucg_put(gpucg);
 	return ERR_PTR(ret);
 }
 
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 2097760e8e95..8e7c55c830b3 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -13,6 +13,7 @@ 
 #ifndef __DMA_BUF_H__
 #define __DMA_BUF_H__
 
+#include <linux/cgroup_gpu.h>
 #include <linux/iosys-map.h>
 #include <linux/file.h>
 #include <linux/err.h>
@@ -303,7 +304,7 @@  struct dma_buf {
 	/**
 	 * @size:
 	 *
-	 * Size of the buffer; invariant over the lifetime of the buffer.
+	 * Size of the buffer in bytes; invariant over the lifetime of the buffer.
 	 */
 	size_t size;
 
@@ -453,6 +454,14 @@  struct dma_buf {
 		struct dma_buf *dmabuf;
 	} *sysfs_entry;
 #endif
+
+#ifdef CONFIG_CGROUP_GPU
+	/** @gpucg: Pointer to the GPU cgroup this buffer currently belongs to. */
+	struct gpucg *gpucg;
+
+	/* @gpucg_bucket: Pointer to the GPU cgroup bucket whence this buffer originates. */
+	struct gpucg_bucket *gpucg_bucket;
+#endif
 };
 
 /**
@@ -526,13 +535,15 @@  struct dma_buf_attachment {
 
 /**
  * struct dma_buf_export_info - holds information needed to export a dma_buf
- * @exp_name:	name of the exporter - useful for debugging.
- * @owner:	pointer to exporter module - used for refcounting kernel module
- * @ops:	Attach allocator-defined dma buf ops to the new buffer
- * @size:	Size of the buffer - invariant over the lifetime of the buffer
- * @flags:	mode flags for the file
- * @resv:	reservation-object, NULL to allocate default one
- * @priv:	Attach private data of allocator to this buffer
+ * @exp_name:		name of the exporter - useful for debugging.
+ * @owner:		pointer to exporter module - used for refcounting kernel module
+ * @ops:		Attach allocator-defined dma buf ops to the new buffer
+ * @size:		Size of the buffer in bytes - invariant over the lifetime of the buffer
+ * @flags:		mode flags for the file
+ * @resv:		reservation-object, NULL to allocate default one
+ * @priv:		Attach private data of allocator to this buffer
+ * @gpucg:		Pointer to GPU cgroup this buffer is charged to, or NULL if not charged
+ * @gpucg_bucket:	Pointer to GPU cgroup bucket this buffer comes from, or NULL if not charged
  *
  * This structure holds the information required to export the buffer. Used
  * with dma_buf_export() only.
@@ -545,6 +556,10 @@  struct dma_buf_export_info {
 	int flags;
 	struct dma_resv *resv;
 	void *priv;
+#ifdef CONFIG_CGROUP_GPU
+	struct gpucg *gpucg;
+	struct gpucg_bucket *gpucg_bucket;
+#endif
 };
 
 /**
@@ -630,4 +645,14 @@  int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 		 unsigned long);
 int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map);
 void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map);
+
+#ifdef CONFIG_CGROUP_GPU
+void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info,
+				struct gpucg *gpucg,
+				struct gpucg_bucket *gpucg_bucket);
+#else/* CONFIG_CGROUP_GPU */
+static inline void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info,
+					      struct gpucg *gpucg,
+					      struct gpucg_bucket *gpucg_bucket) {}
+#endif /* CONFIG_CGROUP_GPU */
 #endif /* __DMA_BUF_H__ */
diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
index 0c05561cad6e..6321e7636538 100644
--- a/include/linux/dma-heap.h
+++ b/include/linux/dma-heap.h
@@ -10,6 +10,7 @@ 
 #define _DMA_HEAPS_H
 
 #include <linux/cdev.h>
+#include <linux/cgroup_gpu.h>
 #include <linux/types.h>
 
 struct dma_heap;
@@ -59,6 +60,20 @@  void *dma_heap_get_drvdata(struct dma_heap *heap);
  */
 const char *dma_heap_get_name(struct dma_heap *heap);
 
+#ifdef CONFIG_CGROUP_GPU
+/**
+ * dma_heap_get_gpucg_bucket() - get a pointer to the struct gpucg_bucket for the heap.
+ * @heap: DMA-Heap to retrieve gpucg_bucket for
+ *
+ * Returns:
+ * The gpucg_bucket struct for the heap.
+ */
+struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap);
+#else /* CONFIG_CGROUP_GPU */
+static inline struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap)
+{ return NULL; }
+#endif /* CONFIG_CGROUP_GPU */
+
 /**
  * dma_heap_add - adds a heap to dmabuf heaps
  * @exp_info:		information needed to register this heap