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.
v2: Consistently use atomics (not mix atomics and helpers) within the
lowlevel get_pages routines. This makes the atomic operations much
clearer.
Fixes: 1233e2db199d ("drm/i915: Move object backing storage manipulation")
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 47 +++++++++++++++++++---------------
drivers/gpu/drm/i915/i915_gem_gtt.c | 7 +++++
drivers/gpu/drm/i915/i915_gem_tiling.c | 1 +
3 files changed, 34 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a7a9ae2c4bce..269e2487c104 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2376,12 +2376,6 @@ 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:
@@ -2414,12 +2408,21 @@ 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)
{
struct sg_table *pages;
+ GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
+
if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {
DRM_DEBUG("Attempting to obtain a purgeable object\n");
return -EFAULT;
@@ -2448,17 +2451,15 @@ 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)) {
+ 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();
+ }
+ atomic_inc(&obj->mm.pages_pin_count);
unlock:
mutex_unlock(&obj->mm.lock);
return err;
@@ -2528,12 +2529,14 @@ void *i915_gem_object_pin_map(struct
drm_i915_gem_object *obj,
pinned = true;
if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {
- ret = ____i915_gem_object_get_pages(obj);
- if (ret)
- goto err_unlock;
+ if (unlikely(!obj->mm.pages)) {
+ ret = ____i915_gem_object_get_pages(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();
+ }
+ atomic_inc(&obj->mm.pages_pin_count);
pinned = false;
}
GEM_BUG_ON(!obj->mm.pages);
@@ -2986,7 +2989,7 @@ 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 */
@@ -3220,6 +3223,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64
alignment, u64 flags)
list_move_tail(&obj->global_link, &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;
@@ -4272,6 +4276,7 @@ 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 3b177c87e862..52999e51a946 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3711,6 +3711,13 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
{
int ret = 0;
+ /* The vma->pages are only valid within the lifespan of the borrowed
+ * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so
+ * must be the vma->pages. A simple rule is that vma->pages must only
+ * be accessed when the obj->mm.pages are pinned.
+ */
+ 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
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