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Commit aae4a3d8 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Use fault-injection to force the shrinker to run in live GTT tests 

It is possible whilst allocating the page-directory tree for a ppgtt
bind that the shrinker may run and reap unused parts of the tree. If the
shrinker happens to remove a chunk of the tree that the
allocate_va_range has already processed, we may then try to insert into
the dangling tree. This test uses the fault-injection framework to force
the shrinker to be invoked before we allocate new pages, i.e. new chunks
of the PD tree.

References: https://bugs.freedesktop.org/show_bug.cgi?id=99295


Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
parent 4a6f13fc

drivers/gpu/drm/i915/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -65,6 +65,7 @@ config DRM_I915_SELFTEST 
	bool "Enable selftests upon driver load"

	depends on DRM_I915

	default n

	select FAULT_INJECTION

	select PRIME_NUMBERS

	help

	  Choose this option to allow the driver to perform selftests upon

drivers/gpu/drm/i915/i915_drv.h

+2 −0
Original line number Diff line number Diff line
@@ -2485,6 +2485,8 @@ struct drm_i915_private { 
	/* Used to save the pipe-to-encoder mapping for audio */

	struct intel_encoder *av_enc_map[I915_MAX_PIPES];



	I915_SELFTEST_DECLARE(struct fault_attr vm_fault);



	/*

	 * NOTE: This is the dri1/ums dungeon, don't add stuff here. Your patch

	 * will be rejected. Instead look for a better place.

drivers/gpu/drm/i915/i915_gem_gtt.c

+6 −0
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ 
 *

 */



#include <linux/slab.h> /* fault-inject.h is not standalone! */



#include <linux/fault-inject.h>

#include <linux/log2.h>

#include <linux/random.h>

#include <linux/seq_file.h>
@@ -345,6 +348,9 @@ static int __setup_page_dma(struct drm_i915_private *dev_priv, 
{

	struct device *kdev = &dev_priv->drm.pdev->dev;



	if (I915_SELFTEST_ONLY(should_fail(&dev_priv->vm_fault, 1)))

		i915_gem_shrink_all(dev_priv);



	p->page = alloc_page(flags);

	if (!p->page)

		return -ENOMEM;

drivers/gpu/drm/i915/i915_selftest.h

+2 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ struct i915_selftest { 
};



#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)

#include <linux/fault-inject.h>



extern struct i915_selftest i915_selftest;



int i915_mock_selftests(void);

drivers/gpu/drm/i915/selftests/i915_gem_gtt.c

+98 −0
Original line number Diff line number Diff line
@@ -271,11 +271,14 @@ static void close_object_list(struct list_head *objects, 
			      struct i915_address_space *vm)

{

	struct drm_i915_gem_object *obj, *on;

	int ignored;



	list_for_each_entry_safe(obj, on, objects, st_link) {

		struct i915_vma *vma;



		vma = i915_vma_instance(obj, vm, NULL);

		if (!IS_ERR(vma))

			ignored = i915_vma_unbind(vma);

		/* Only ppgtt vma may be closed before the object is freed */

		if (!IS_ERR(vma) && !i915_vma_is_ggtt(vma))

			i915_vma_close(vma);
@@ -677,6 +680,95 @@ static int drunk_hole(struct drm_i915_private *i915, 
	return 0;

}



static int __shrink_hole(struct drm_i915_private *i915,

			 struct i915_address_space *vm,

			 u64 hole_start, u64 hole_end,

			 unsigned long end_time)

{

	struct drm_i915_gem_object *obj;

	unsigned long flags = PIN_OFFSET_FIXED | PIN_USER;

	unsigned int order = 12;

	LIST_HEAD(objects);

	int err = 0;

	u64 addr;



	/* Keep creating larger objects until one cannot fit into the hole */

	for (addr = hole_start; addr < hole_end; ) {

		struct i915_vma *vma;

		u64 size = BIT_ULL(order++);



		size = min(size, hole_end - addr);

		obj = fake_dma_object(i915, size);

		if (IS_ERR(obj)) {

			err = PTR_ERR(obj);

			break;

		}



		list_add(&obj->st_link, &objects);



		vma = i915_vma_instance(obj, vm, NULL);

		if (IS_ERR(vma)) {

			err = PTR_ERR(vma);

			break;

		}



		GEM_BUG_ON(vma->size != size);



		err = i915_vma_pin(vma, 0, 0, addr | flags);

		if (err) {

			pr_err("%s failed to pin object at %llx + %llx in hole [%llx - %llx], with err=%d\n",

			       __func__, addr, size, hole_start, hole_end, err);

			break;

		}



		if (!drm_mm_node_allocated(&vma->node) ||

		    i915_vma_misplaced(vma, 0, 0, addr | flags)) {

			pr_err("%s incorrect at %llx + %llx\n",

			       __func__, addr, size);

			i915_vma_unpin(vma);

			err = i915_vma_unbind(vma);

			err = -EINVAL;

			break;

		}



		i915_vma_unpin(vma);

		addr += size;



		if (igt_timeout(end_time,

				"%s timed out at ofset %llx [%llx - %llx]\n",

				__func__, addr, hole_start, hole_end)) {

			err = -EINTR;

			break;

		}

	}



	close_object_list(&objects, vm);

	return err;

}



static int shrink_hole(struct drm_i915_private *i915,

		       struct i915_address_space *vm,

		       u64 hole_start, u64 hole_end,

		       unsigned long end_time)

{

	unsigned long prime;

	int err;



	i915->vm_fault.probability = 999;

	atomic_set(&i915->vm_fault.times, -1);



	for_each_prime_number_from(prime, 0, ULONG_MAX - 1) {

		i915->vm_fault.interval = prime;

		err = __shrink_hole(i915, vm, hole_start, hole_end, end_time);

		if (err)

			break;

	}



	memset(&i915->vm_fault, 0, sizeof(i915->vm_fault));



	return err;

}



static int exercise_ppgtt(struct drm_i915_private *dev_priv,

			  int (*func)(struct drm_i915_private *i915,

				      struct i915_address_space *vm,
@@ -735,6 +827,11 @@ static int igt_ppgtt_lowlevel(void *arg) 
	return exercise_ppgtt(arg, lowlevel_hole);

}



static int igt_ppgtt_shrink(void *arg)

{

	return exercise_ppgtt(arg, shrink_hole);

}



static int sort_holes(void *priv, struct list_head *A, struct list_head *B)

{

	struct drm_mm_node *a = list_entry(A, typeof(*a), hole_stack);
@@ -812,6 +909,7 @@ int i915_gem_gtt_live_selftests(struct drm_i915_private *i915) 
		SUBTEST(igt_ppgtt_drunk),

		SUBTEST(igt_ppgtt_walk),

		SUBTEST(igt_ppgtt_fill),

		SUBTEST(igt_ppgtt_shrink),

		SUBTEST(igt_ggtt_lowlevel),

		SUBTEST(igt_ggtt_drunk),

		SUBTEST(igt_ggtt_walk),