drm/i915/gem: Hold the obj->vma.lock while walking the vma.list

Remember to take the lock before walking the obj->vma.list so that the
nodes do not change beneath us! E.g.,

i915_gem_object_bump_inactive_ggtt:387 GEM_BUG_ON(vma->vm != &i915->ggtt.vm)

Closes: https://gitlab.freedesktop.org/drm/intel/issues/691
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191204164527.3872783-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index f2064950622b0e25f1234904509a28522af2b0b8..808eb327a29bde23b678319b267f7833b02f6a89 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -379,8 +379,11 @@ static void i915_gem_object_bump_inactive_ggtt(struct drm_i915_gem_object *obj)
        struct i915_vma *vma;
 
        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
+       if (!atomic_read(&obj->bind_count))
+               return;
 
        mutex_lock(&i915->ggtt.vm.mutex);
+       spin_lock(&obj->vma.lock);
        for_each_ggtt_vma(vma, obj) {
                if (!drm_mm_node_allocated(&vma->node))
                        continue;
@@ -388,6 +391,7 @@ static void i915_gem_object_bump_inactive_ggtt(struct drm_i915_gem_object *obj)
                GEM_BUG_ON(vma->vm != &i915->ggtt.vm);
                list_move_tail(&vma->vm_link, &vma->vm->bound_list);
        }
+       spin_unlock(&obj->vma.lock);
        mutex_unlock(&i915->ggtt.vm.mutex);
 
        if (i915_gem_object_is_shrinkable(obj)) {