On 07/07/16 09:41, Chris Wilson wrote:
Since we may have VMA allocated for an object, but we interrupted their
binding, there is a disparity between have elements on the obj->vma_list
and being bound. i915_gem_obj_bound_any() does this check, but this is
not rigorously observed - add an explicit count to make it easier.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
  drivers/gpu/drm/i915/i915_debugfs.c      | 12 +++++------
  drivers/gpu/drm/i915/i915_drv.h          |  3 ++-
  drivers/gpu/drm/i915/i915_gem.c          | 34 +++++++++++++-------------------
  drivers/gpu/drm/i915/i915_gem_shrinker.c | 17 +---------------
  drivers/gpu/drm/i915/i915_gem_stolen.c   |  1 +
  5 files changed, 23 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index 327064823bb0..d3852828878f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -174,6 +174,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object 
*obj)
        if (obj->fence_reg != I915_FENCE_REG_NONE)
                seq_printf(m, " (fence: %d)", obj->fence_reg);
        list_for_each_entry(vma, &obj->vma_list, obj_link) {
+               if (!drm_mm_node_allocated(&vma->node))
+                       continue;
+
                seq_printf(m, " (%sgtt offset: %08llx, size: %08llx",
                           vma->is_ggtt ? "g" : "pp",
                           vma->node.start, vma->node.size);
@@ -335,11 +338,11 @@ static int per_file_stats(int id, void *ptr, void *data)
        struct drm_i915_gem_object *obj = ptr;
        struct file_stats *stats = data;
        struct i915_vma *vma;
-       int bound = 0;

        stats->count++;
        stats->total += obj->base.size;
-
+       if (!obj->bind_count)
+               stats->unbound += obj->base.size;
        if (obj->base.name || obj->base.dma_buf)
                stats->shared += obj->base.size;

@@ -347,8 +350,6 @@ static int per_file_stats(int id, void *ptr, void *data)
                if (!drm_mm_node_allocated(&vma->node))
                        continue;

-               bound++;
-
                if (vma->is_ggtt) {
                        stats->global += vma->node.size;
                } else {
@@ -366,9 +367,6 @@ static int per_file_stats(int id, void *ptr, void *data)
                        stats->inactive += vma->node.size;
        }

-       if (!bound)
-               stats->unbound += obj->base.size;
-
        return 0;
  }

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a19d18ea074e..633585054669 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2217,6 +2217,8 @@ struct drm_i915_gem_object {
        unsigned int frontbuffer_bits:INTEL_FRONTBUFFER_BITS;

        unsigned int has_wc_mmap;
+       /** Count of VMA actually bound by this object */
+       unsigned int bind_count;
        unsigned int pin_display;

        struct sg_table *pages;
@@ -3246,7 +3248,6 @@ i915_gem_obj_ggtt_offset(struct drm_i915_gem_object *o)
        return i915_gem_obj_ggtt_offset_view(o, &i915_ggtt_view_normal);
  }

-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o);
  bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
                                  const struct i915_ggtt_view *view);
  bool i915_gem_obj_bound(struct drm_i915_gem_object *o,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 98f3945fc50f..c6816f9969d5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2107,7 +2107,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
        if (obj->pages_pin_count)
                return -EBUSY;

-       BUG_ON(i915_gem_obj_bound_any(obj));
+       GEM_BUG_ON(obj->bind_count);

        /* ->put_pages might need to allocate memory for the bit17 swizzle
         * array, hence protect them from being reaped by removing them from gtt
@@ -2957,7 +2957,6 @@ static void __i915_vma_iounmap(struct i915_vma *vma)
  static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
  {
        struct drm_i915_gem_object *obj = vma->obj;
-       struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        int ret;

        if (list_empty(&vma->obj_link))
@@ -2971,7 +2970,8 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool 
wait)
        if (vma->pin_count)
                return -EBUSY;

-       BUG_ON(obj->pages == NULL);
+       GEM_BUG_ON(obj->bind_count == 0);
+       GEM_BUG_ON(!obj->pages);

        if (wait) {
                ret = i915_gem_object_wait_rendering(obj, false);
@@ -3011,8 +3011,9 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool 
wait)

        /* Since the unbound list is global, only move to that list if
         * no more VMAs exist. */
-       if (list_empty(&obj->vma_list))
-               list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);
+       if (--obj->bind_count == 0)
+               list_move_tail(&obj->global_list,
+                              &to_i915(obj->base.dev)->mm.unbound_list);

        /* And finally now the object is completely decoupled from this vma,
         * we can drop its hold on the backing storage and allow it to be
@@ -3247,6 +3248,7 @@ search_free:

        list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
        list_add_tail(&vma->vm_link, &vm->inactive_list);
+       obj->bind_count++;

        return vma;

@@ -3442,7 +3444,6 @@ int i915_gem_object_set_cache_level(struct 
drm_i915_gem_object *obj,
  {
        struct drm_device *dev = obj->base.dev;
        struct i915_vma *vma, *next;
-       bool bound = false;
        int ret = 0;

        if (obj->cache_level == cache_level)
@@ -3466,8 +3467,7 @@ int i915_gem_object_set_cache_level(struct 
drm_i915_gem_object *obj,
                        ret = i915_vma_unbind(vma);
                        if (ret)
                                return ret;
-               } else
-                       bound = true;
+               }
        }

        /* We can reuse the existing drm_mm nodes but need to change the
@@ -3477,7 +3477,7 @@ int i915_gem_object_set_cache_level(struct 
drm_i915_gem_object *obj,
         * rewrite the PTE in the belief that doing so tramples upon less
         * state and so involves less work.
         */
-       if (bound) {
+       if (obj->bind_count) {
                /* Before we change the PTE, the GPU must not be accessing it.
                 * If we wait upon the object, we know that all the bound
                 * VMA are no longer active.
@@ -3684,6 +3684,9 @@ i915_gem_object_pin_to_display_plane(struct 
drm_i915_gem_object *obj,
                                            old_read_domains,
                                            old_write_domain);

+       /* Increment the pages_pin_count to guard against the shrinker */
+       obj->pages_pin_count++;

Would it be clearer to look at obj->pin_display in the shrinker? Although it looks like special casing out of the cleanliness of the design in both case so I am not sure.

+
        return 0;

  err_unpin_display:
@@ -3700,6 +3703,7 @@ i915_gem_object_unpin_from_display_plane(struct 
drm_i915_gem_object *obj,

        i915_gem_object_ggtt_unpin_view(obj, view);

+       obj->pages_pin_count--;
        obj->pin_display--;
  }

@@ -4215,6 +4219,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
                        dev_priv->mm.interruptible = was_interruptible;
                }
        }
+       GEM_BUG_ON(obj->bind_count);

        /* Stolen objects don't hold a ref, but do hold pin count. Fix that up
         * before progressing. */
@@ -4851,17 +4856,6 @@ bool i915_gem_obj_ggtt_bound_view(struct 
drm_i915_gem_object *o,
        return false;
  }

-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o)
-{
-       struct i915_vma *vma;
-
-       list_for_each_entry(vma, &o->vma_list, obj_link)
-               if (drm_mm_node_allocated(&vma->node))
-                       return true;
-
-       return false;
-}
-
  unsigned long i915_gem_obj_ggtt_size(struct drm_i915_gem_object *o)
  {
        struct i915_vma *vma;
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c 
b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index e93a837cf2a1..725a8c894517 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -48,21 +48,6 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct 
task_struct *task)
  #endif
  }

-static int num_vma_bound(struct drm_i915_gem_object *obj)
-{
-       struct i915_vma *vma;
-       int count = 0;
-
-       list_for_each_entry(vma, &obj->vma_list, obj_link) {
-               if (drm_mm_node_allocated(&vma->node))
-                       count++;
-               if (vma->pin_count)
-                       count++;
-       }
-
-       return count;
-}
-
  static bool swap_available(void)
  {
        return get_nr_swap_pages() > 0;
@@ -82,7 +67,7 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
         * to the GPU, simply unbinding from the GPU is not going to succeed
         * in releasing our pin count on the pages themselves.
         */
-       if (obj->pages_pin_count != num_vma_bound(obj))
+       if (obj->pages_pin_count != obj->bind_count)

Would this be clearer as obj->pages_pin_count > obj->bind_count ?

                return false;

        /* We can only return physical pages to the system if we can either
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c 
b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 9a8cc8c51077..2c321c8df7c3 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -708,6 +708,7 @@ i915_gem_object_create_stolen_for_preallocated(struct 
drm_device *dev,
        vma->bound |= GLOBAL_BIND;
        __i915_vma_set_map_and_fenceable(vma);
        list_add_tail(&vma->vm_link, &ggtt->base.inactive_list);
+       obj->bind_count++;

        list_add_tail(&obj->global_list, &dev_priv->mm.bound_list);
        i915_gem_object_pin_pages(obj);


Looks fine to me.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Regards,

Tvrtko
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