[PATCH RFC 3/3] drm/ttm: support memcg for ttm_tt

[Qiang Yu]

Charge TTM allocated system memory to memory cgroup which will
limit the memory usage of a group of processes.

The memory is always charged to the control group of task which
create this buffer object and when it's created. For example,
when a buffer is created by process A and exported to process B,
then process B populate this buffer, the memory is still charged
to process A's memcg; if a buffer is created by process A when in
memcg B, then A is moved to memcg C and populate this buffer, it
will charge memcg B.

Signed-off-by: Qiang Yu <qiang.yu at amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c         | 10 ++++++++++
 drivers/gpu/drm/ttm/ttm_page_alloc.c | 18 +++++++++++++++++-
 drivers/gpu/drm/ttm/ttm_tt.c         |  3 +++
 include/drm/ttm/ttm_bo_api.h         |  5 +++++
 include/drm/ttm/ttm_tt.h             |  4 ++++
 5 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 8d91b0428af1..4e64846ee523 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -42,6 +42,7 @@
 #include <linux/module.h>
 #include <linux/atomic.h>
 #include <linux/dma-resv.h>
+#include <linux/memcontrol.h>
 
 static void ttm_bo_global_kobj_release(struct kobject *kobj);
 
@@ -162,6 +163,10 @@ static void ttm_bo_release_list(struct kref *list_kref)
 	if (!ttm_bo_uses_embedded_gem_object(bo))
 		dma_resv_fini(&bo->base._resv);
 	mutex_destroy(&bo->wu_mutex);
+#ifdef CONFIG_MEMCG
+	if (bo->memcg)
+		css_put(&bo->memcg->css);
+#endif
 	bo->destroy(bo);
 	ttm_mem_global_free(&ttm_mem_glob, acc_size);
 }
@@ -1330,6 +1335,11 @@ int ttm_bo_init_reserved(struct ttm_bo_device *bdev,
 	}
 	atomic_inc(&ttm_bo_glob.bo_count);
 
+#ifdef CONFIG_MEMCG
+	if (bo->type == ttm_bo_type_device)
+		bo->memcg = mem_cgroup_driver_get_from_current();
+#endif
+
 	/*
 	 * For ttm_bo_type_device buffers, allocate
 	 * address space from the device.
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index b40a4678c296..ecd1831a1d38 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -42,7 +42,7 @@
 #include <linux/seq_file.h> /* for seq_printf */
 #include <linux/slab.h>
 #include <linux/dma-mapping.h>
-
+#include <linux/memcontrol.h>
 #include <linux/atomic.h>
 
 #include <drm/ttm/ttm_bo_driver.h>
@@ -1045,6 +1045,11 @@ ttm_pool_unpopulate_helper(struct ttm_tt *ttm, unsigned mem_count_update)
 	ttm_put_pages(ttm->pages, ttm->num_pages, ttm->page_flags,
 		      ttm->caching_state);
 	ttm->state = tt_unpopulated;
+
+#ifdef CONFIG_MEMCG
+	if (ttm->memcg)
+		mem_cgroup_uncharge_drvmem(ttm->memcg, ttm->num_pages);
+#endif
 }
 
 int ttm_pool_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
@@ -1059,6 +1064,17 @@ int ttm_pool_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
 	if (ttm_check_under_lowerlimit(mem_glob, ttm->num_pages, ctx))
 		return -ENOMEM;
 
+#ifdef CONFIG_MEMCG
+	if (ttm->memcg) {
+		gfp_t gfp_flags = GFP_USER;
+		if (ttm->page_flags & TTM_PAGE_FLAG_NO_RETRY)
+			gfp_flags |= __GFP_RETRY_MAYFAIL;
+		ret = mem_cgroup_charge_drvmem(ttm->memcg, gfp_flags, ttm->num_pages);
+		if (ret)
+			return ret;
+	}
+#endif
+
 	ret = ttm_get_pages(ttm->pages, ttm->num_pages, ttm->page_flags,
 			    ttm->caching_state);
 	if (unlikely(ret != 0)) {
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index e0e9b4f69db6..1acb153084e1 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -233,6 +233,9 @@ void ttm_tt_init_fields(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
 	ttm->state = tt_unpopulated;
 	ttm->swap_storage = NULL;
 	ttm->sg = bo->sg;
+#ifdef CONFIG_MEMCG
+	ttm->memcg = bo->memcg;
+#endif
 }
 
 int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 65e399d280f7..95a08e81a73e 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -54,6 +54,8 @@ struct ttm_place;
 
 struct ttm_lru_bulk_move;
 
+struct mem_cgroup;
+
 /**
  * struct ttm_bus_placement
  *
@@ -180,6 +182,9 @@ struct ttm_buffer_object {
 	void (*destroy) (struct ttm_buffer_object *);
 	unsigned long num_pages;
 	size_t acc_size;
+#ifdef CONFIG_MEMCG
+	struct mem_cgroup *memcg;
+#endif
 
 	/**
 	* Members not needing protection.
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
index c0e928abf592..10fb5a557b95 100644
--- a/include/drm/ttm/ttm_tt.h
+++ b/include/drm/ttm/ttm_tt.h
@@ -33,6 +33,7 @@ struct ttm_tt;
 struct ttm_mem_reg;
 struct ttm_buffer_object;
 struct ttm_operation_ctx;
+struct mem_cgroup;
 
 #define TTM_PAGE_FLAG_WRITE           (1 << 3)
 #define TTM_PAGE_FLAG_SWAPPED         (1 << 4)
@@ -116,6 +117,9 @@ struct ttm_tt {
 		tt_unbound,
 		tt_unpopulated,
 	} state;
+#ifdef CONFIG_MEMCG
+	struct mem_cgroup *memcg;
+#endif
 };
 
 /**
-- 
2.17.1