Merge tag 'cgroup-dmem-drm-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/mripard/linux into drm-next

DMEM cgroup pull request

This introduces a new cgroup controller to limit the device memory.
Notable users would be DRM, dma-buf heaps, or v4l2.

This pull request is based on the series developped by Maarten
Lankhorst, Friedrich Vock, and I:
https://lore.kernel.org/all/20241204134410.1161769-1-dev@lankhorst.se/

Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maxime Ripard <mripard@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250110-cryptic-warm-mandrill-b71f5d@houat

Author: airlied

Documentation/admin-guide/cgroup-v2.rst

@@ -64,13 +64,14 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
      5-6. Device
      5-7. RDMA
        5-7-1. RDMA Interface Files
-     5-8. HugeTLB
-       5.8-1. HugeTLB Interface Files
-     5-9. Misc
-       5.9-1 Miscellaneous cgroup Interface Files
-       5.9-2 Migration and Ownership
-     5-10. Others
-       5-10-1. perf_event
+     5-8. DMEM
+     5-9. HugeTLB
+       5.9-1. HugeTLB Interface Files
+     5-10. Misc
+       5.10-1 Miscellaneous cgroup Interface Files
+       5.10-2 Migration and Ownership
+     5-11. Others
+       5-11-1. perf_event
      5-N. Non-normative information
        5-N-1. CPU controller root cgroup process behaviour
        5-N-2. IO controller root cgroup process behaviour
@@ -2626,6 +2627,49 @@ RDMA Interface Files
 	  mlx4_0 hca_handle=1 hca_object=20
 	  ocrdma1 hca_handle=1 hca_object=23
 
+DMEM
+----
+
+The "dmem" controller regulates the distribution and accounting of
+device memory regions. Because each memory region may have its own page size,
+which does not have to be equal to the system page size, the units are always bytes.
+
+DMEM Interface Files
+~~~~~~~~~~~~~~~~~~~~
+
+  dmem.max, dmem.min, dmem.low
+	A readwrite nested-keyed file that exists for all the cgroups
+	except root that describes current configured resource limit
+	for a region.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 1073741824
+	  drm/0000:03:00.0/stolen max
+
+	The semantics are the same as for the memory cgroup controller, and are
+	calculated in the same way.
+
+  dmem.capacity
+	A read-only file that describes maximum region capacity.
+	It only exists on the root cgroup. Not all memory can be
+	allocated by cgroups, as the kernel reserves some for
+	internal use.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 8514437120
+	  drm/0000:03:00.0/stolen 67108864
+
+  dmem.current
+	A read-only file that describes current resource usage.
+	It exists for all the cgroup except root.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 12550144
+	  drm/0000:03:00.0/stolen 8650752
+
 HugeTLB
 -------
 

Documentation/core-api/cgroup.rst

@@ -0,0 +1,9 @@
+==================
+Cgroup Kernel APIs
+==================
+
+Device Memory Cgroup API (dmemcg)
+=========================
+.. kernel-doc:: kernel/cgroup/dmem.c
+   :export:
+

Documentation/core-api/index.rst

@@ -109,6 +109,7 @@ more memory-management documentation in Documentation/mm/index.rst.
    dma-isa-lpc
    swiotlb
    mm-api
+   cgroup
    genalloc
    pin_user_pages
    boot-time-mm

Documentation/gpu/drm-compute.rst

@@ -0,0 +1,54 @@
+==================================
+Long running workloads and compute
+==================================
+
+Long running workloads (compute) are workloads that will not complete in 10
+seconds. (The time let the user wait before he reaches for the power button).
+This means that other techniques need to be used to manage those workloads,
+that cannot use fences.
+
+Some hardware may schedule compute jobs, and have no way to pre-empt them, or
+have their memory swapped out from them. Or they simply want their workload
+not to be preempted or swapped out at all.
+
+This means that it differs from what is described in driver-api/dma-buf.rst.
+
+As with normal compute jobs, dma-fence may not be used at all. In this case,
+not even to force preemption. The driver with is simply forced to unmap a BO
+from the long compute job's address space on unbind immediately, not even
+waiting for the workload to complete. Effectively this terminates the workload
+when there is no hardware support to recover.
+
+Since this is undesirable, there need to be mitigations to prevent a workload
+from being terminated. There are several possible approach, all with their
+advantages and drawbacks.
+
+The first approach you will likely try is to pin all buffers used by compute.
+This guarantees that the job will run uninterrupted, but also allows a very
+denial of service attack by pinning as much memory as possible, hogging the
+all GPU memory, and possibly a huge chunk of CPU memory.
+
+A second approach that will work slightly better on its own is adding an option
+not to evict when creating a new job (any kind). If all of userspace opts in
+to this flag, it would prevent cooperating userspace from forced terminating
+older compute jobs to start a new one.
+
+If job preemption and recoverable pagefaults are not available, those are the
+only approaches possible. So even with those, you want a separate way of
+controlling resources. The standard kernel way of doing so is cgroups.
+
+This creates a third option, using cgroups to prevent eviction. Both GPU and
+driver-allocated CPU memory would be accounted to the correct cgroup, and
+eviction would be made cgroup aware. This allows the GPU to be partitioned
+into cgroups, that will allow jobs to run next to each other without
+interference.
+
+The interface to the cgroup would be similar to the current CPU memory
+interface, with similar semantics for min/low/high/max, if eviction can
+be made cgroup aware.
+
+What should be noted is that each memory region (tiled memory for example)
+should have its own accounting.
+
+The key is set to the regionid set by the driver, for example "tile0".
+For the value of $card, we use drmGetUnique().

drivers/gpu/drm/drm_drv.c

@@ -26,6 +26,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/cgroup_dmem.h>
 #include <linux/debugfs.h>
 #include <linux/fs.h>
 #include <linux/module.h>
@@ -820,6 +821,37 @@ void drm_dev_put(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_dev_put);
 
+static void drmm_cg_unregister_region(struct drm_device *dev, void *arg)
+{
+	dmem_cgroup_unregister_region(arg);
+}
+
+/**
+ * drmm_cgroup_register_region - Register a region of a DRM device to cgroups
+ * @dev: device for region
+ * @region_name: Region name for registering
+ * @size: Size of region in bytes
+ *
+ * This decreases the ref-count of @dev by one. The device is destroyed if the
+ * ref-count drops to zero.
+ */
+struct dmem_cgroup_region *drmm_cgroup_register_region(struct drm_device *dev, const char *region_name, u64 size)
+{
+	struct dmem_cgroup_region *region;
+	int ret;
+
+	region = dmem_cgroup_register_region(size, "drm/%s/%s", dev->unique, region_name);
+	if (IS_ERR_OR_NULL(region))
+		return region;
+
+	ret = drmm_add_action_or_reset(dev, drmm_cg_unregister_region, region);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return region;
+}
+EXPORT_SYMBOL_GPL(drmm_cgroup_register_region);
+
 static int create_compat_control_link(struct drm_device *dev)
 {
 	struct drm_minor *minor;

drivers/gpu/drm/ttm/tests/ttm_bo_test.c

@@ -258,13 +258,13 @@ static void ttm_bo_unreserve_basic(struct kunit *test)
 	bo = ttm_bo_kunit_init(test, test->priv, BO_SIZE, NULL);
 	bo->priority = bo_prio;
 
-	err = ttm_resource_alloc(bo, place, &res1);
+	err = ttm_resource_alloc(bo, place, &res1, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 
 	bo->resource = res1;
 
 	/* Add a dummy resource to populate LRU */
-	ttm_resource_alloc(bo, place, &res2);
+	ttm_resource_alloc(bo, place, &res2, NULL);
 
 	dma_resv_lock(bo->base.resv, NULL);
 	ttm_bo_unreserve(bo);
@@ -300,12 +300,12 @@ static void ttm_bo_unreserve_pinned(struct kunit *test)
 	dma_resv_lock(bo->base.resv, NULL);
 	ttm_bo_pin(bo);
 
-	err = ttm_resource_alloc(bo, place, &res1);
+	err = ttm_resource_alloc(bo, place, &res1, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo->resource = res1;
 
 	/* Add a dummy resource to the pinned list */
-	err = ttm_resource_alloc(bo, place, &res2);
+	err = ttm_resource_alloc(bo, place, &res2, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	KUNIT_ASSERT_EQ(test,
 			list_is_last(&res2->lru.link, &priv->ttm_dev->unevictable), 1);
@@ -355,15 +355,15 @@ static void ttm_bo_unreserve_bulk(struct kunit *test)
 	ttm_bo_set_bulk_move(bo1, &lru_bulk_move);
 	dma_resv_unlock(bo1->base.resv);
 
-	err = ttm_resource_alloc(bo1, place, &res1);
+	err = ttm_resource_alloc(bo1, place, &res1, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo1->resource = res1;
 
 	dma_resv_lock(bo2->base.resv, NULL);
 	ttm_bo_set_bulk_move(bo2, &lru_bulk_move);
 	dma_resv_unlock(bo2->base.resv);
 
-	err = ttm_resource_alloc(bo2, place, &res2);
+	err = ttm_resource_alloc(bo2, place, &res2, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo2->resource = res2;
 
@@ -401,7 +401,7 @@ static void ttm_bo_put_basic(struct kunit *test)
 	bo = ttm_bo_kunit_init(test, test->priv, BO_SIZE, NULL);
 	bo->type = ttm_bo_type_device;
 
-	err = ttm_resource_alloc(bo, place, &res);
+	err = ttm_resource_alloc(bo, place, &res, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo->resource = res;
 
@@ -518,7 +518,7 @@ static void ttm_bo_pin_unpin_resource(struct kunit *test)
 
 	bo = ttm_bo_kunit_init(test, test->priv, BO_SIZE, NULL);
 
-	err = ttm_resource_alloc(bo, place, &res);
+	err = ttm_resource_alloc(bo, place, &res, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo->resource = res;
 
@@ -569,7 +569,7 @@ static void ttm_bo_multiple_pin_one_unpin(struct kunit *test)
 
 	bo = ttm_bo_kunit_init(test, test->priv, BO_SIZE, NULL);
 
-	err = ttm_resource_alloc(bo, place, &res);
+	err = ttm_resource_alloc(bo, place, &res, NULL);
 	KUNIT_ASSERT_EQ(test, err, 0);
 	bo->resource = res;
 

drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c

@@ -542,7 +542,7 @@ static void ttm_bo_validate_no_placement_signaled(struct kunit *test)
 		bo->ttm = old_tt;
 	}
 
-	err = ttm_resource_alloc(bo, place, &bo->resource);
+	err = ttm_resource_alloc(bo, place, &bo->resource, NULL);
 	KUNIT_EXPECT_EQ(test, err, 0);
 	KUNIT_ASSERT_EQ(test, man->usage, size);
 
@@ -603,7 +603,7 @@ static void ttm_bo_validate_no_placement_not_signaled(struct kunit *test)
 	bo = ttm_bo_kunit_init(test, test->priv, size, NULL);
 	bo->type = params->bo_type;
 
-	err = ttm_resource_alloc(bo, place, &bo->resource);
+	err = ttm_resource_alloc(bo, place, &bo->resource, NULL);
 	KUNIT_EXPECT_EQ(test, err, 0);
 
 	placement = kunit_kzalloc(test, sizeof(*placement), GFP_KERNEL);

drivers/gpu/drm/ttm/tests/ttm_resource_test.c

@@ -302,7 +302,7 @@ static void ttm_sys_man_free_basic(struct kunit *test)
 	res = kunit_kzalloc(test, sizeof(*res), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_NULL(test, res);
 
-	ttm_resource_alloc(bo, place, &res);
+	ttm_resource_alloc(bo, place, &res, NULL);
 
 	man = ttm_manager_type(priv->devs->ttm_dev, mem_type);
 	man->func->free(man, res);