On Wed, Nov 02, 2016 at 09:43:54AM +0000, Chris Wilson wrote:
> commit bc0629a76726 ("drm/i915: Track pages pinned due to swizzling
> quirk") fixed one problem, but revealed a whole lot more. The root cause
> of the pin count mismatch for the swizzle quirk (for L-shaped memory on
> gen3/4) was that we were incrementing the pages_pin_count upon getting
> the backing pages but then overwriting the pages_pin_count to set it to
> 1 afterwards. With a little bit of adjustment to satisfy the GEM_BUG_ON
> sanitychecks, the fix is to replace the explicit atomic_set with an
> atomic_inc.
>
> Fixes: 1233e2db199d ("drm/i915: Move object backing storage manipulation")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Ping?
> ---
> drivers/gpu/drm/i915/i915_gem.c | 40 ++++++++++++++++++----------------
> drivers/gpu/drm/i915/i915_gem_gtt.c | 1 +
> drivers/gpu/drm/i915/i915_gem_tiling.c | 1 +
> 3 files changed, 23 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 993fb90da104..5fe7562aefbd 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2386,12 +2386,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
> if (i915_gem_object_needs_bit17_swizzle(obj))
> i915_gem_object_do_bit_17_swizzle(obj, st);
>
> - if (i915_gem_object_is_tiled(obj) &&
> - dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
> - __i915_gem_object_pin_pages(obj);
> - obj->mm.quirked = true;
> - }
> -
> return st;
>
> err_pages:
> @@ -2424,6 +2418,13 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
> obj->mm.get_page.sg_idx = 0;
>
> obj->mm.pages = pages;
> +
> + if (i915_gem_object_is_tiled(obj) &&
> + to_i915(obj->base.dev)->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
> + GEM_BUG_ON(obj->mm.quirked);
> + __i915_gem_object_pin_pages(obj);
> + obj->mm.quirked = true;
> + }
> }
>
> static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
> @@ -2458,17 +2459,16 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
> if (err)
> return err;
>
> - if (likely(obj->mm.pages)) {
> - __i915_gem_object_pin_pages(obj);
> - goto unlock;
> - }
> -
> - GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
> + if (unlikely(!obj->mm.pages)) {
> + GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
> + err = ____i915_gem_object_get_pages(obj);
> + if (err)
> + goto unlock;
>
> - err = ____i915_gem_object_get_pages(obj);
> - if (!err)
> - atomic_set_release(&obj->mm.pages_pin_count, 1);
> + smp_mb__before_atomic();
> + }
>
> + __i915_gem_object_pin_pages(obj);
> unlock:
> mutex_unlock(&obj->mm.lock);
> return err;
> @@ -2542,8 +2542,8 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
> if (ret)
> goto err_unlock;
>
> - GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count));
> - atomic_set_release(&obj->mm.pages_pin_count, 1);
> + smp_mb__before_atomic();
> + __i915_gem_object_pin_pages(obj);
> pinned = false;
> }
> GEM_BUG_ON(!obj->mm.pages);
> @@ -2578,7 +2578,7 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
> return ptr;
>
> err_unpin:
> - atomic_dec(&obj->mm.pages_pin_count);
> + __i915_gem_object_unpin_pages(obj);
> err_unlock:
> ptr = ERR_PTR(ret);
> goto out_unlock;
> @@ -2996,7 +2996,7 @@ int i915_vma_unbind(struct i915_vma *vma)
> goto destroy;
>
> GEM_BUG_ON(obj->bind_count == 0);
> - GEM_BUG_ON(!obj->mm.pages);
> + GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
>
> if (i915_vma_is_map_and_fenceable(vma)) {
> /* release the fence reg _after_ flushing */
> @@ -3230,6 +3230,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
> list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
> list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
> obj->bind_count++;
> + GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
>
> return 0;
>
> @@ -4282,6 +4283,7 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
> obj->mm.quirked = false;
> }
> if (args->madv == I915_MADV_WILLNEED) {
> + GEM_BUG_ON(obj->mm.quirked);
> __i915_gem_object_pin_pages(obj);
> obj->mm.quirked = true;
> }
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index dfc40f16f149..4dc1a463ef4c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -3707,6 +3707,7 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
> {
> int ret = 0;
>
> + GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));
> if (vma->pages)
> return 0;
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> index 1577e7810cd6..251d51b01174 100644
> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> @@ -269,6 +269,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
> obj->mm.quirked = false;
> }
> if (!i915_gem_object_is_tiled(obj)) {
> + GEM_BUG_ON(!obj->mm.quirked);
> __i915_gem_object_pin_pages(obj);
> obj->mm.quirked = true;
> }
> --
> 2.10.2
>
--
Chris Wilson, Intel Open Source Technology Centre
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