On 5/18/21 1:12 PM, Maarten Lankhorst wrote:
Hey,
This needs a small fix, otherwise looks good.
Op 18-05-2021 om 10:26 schreef Thomas Hellström:
From: Thomas Hellström <thomas.hellstrom@xxxxxxxxx>
Any sleeping dma_resv lock taken while the vma pages_mutex is held
will cause a lockdep splat.
Move the i915_gem_object_pin_pages() call out of the pages_mutex
critical section.
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_vma.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index a6cd0fa62847..7b1c0f4e60d7 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -800,32 +800,37 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
static int vma_get_pages(struct i915_vma *vma)
{
int err = 0;
+ bool pinned_pages = false;
if (atomic_add_unless(&vma->pages_count, 1, 0))
return 0;
+ if (vma->obj) {
+ err = i915_gem_object_pin_pages(vma->obj);
+ if (err)
+ return err;
+ pinned_pages = true;
+ }
+
/* Allocations ahoy! */
- if (mutex_lock_interruptible(&vma->pages_mutex))
- return -EINTR;
+ if (mutex_lock_interruptible(&vma->pages_mutex)) {
+ err = -EINTR;
+ goto unpin;
+ }
if (!atomic_read(&vma->pages_count)) {
- if (vma->obj) {
- err = i915_gem_object_pin_pages(vma->obj);
- if (err)
- goto unlock;
- }
-
err = vma->ops->set_pages(vma);
- if (err) {
- if (vma->obj)
- i915_gem_object_unpin_pages(vma->obj);
+ if (err)
goto unlock;
- }
+ pinned_pages = false;
}
atomic_inc(&vma->pages_count);
unlock:
mutex_unlock(&vma->pages_mutex);
+unpin:
+ if (pinned_pages)
+ __i915_gem_object_unpin_pages(vma->obj);
return err;
}
@@ -838,10 +843,10 @@ static void __vma_put_pages(struct i915_vma *vma, unsigned int count)
if (atomic_sub_return(count, &vma->pages_count) == 0) {
vma->ops->clear_pages(vma);
GEM_BUG_ON(vma->pages);
- if (vma->obj)
- i915_gem_object_unpin_pages(vma->obj);
}
mutex_unlock(&vma->pages_mutex);
+ if (vma->obj)
+ i915_gem_object_unpin_pages(vma->obj);
You're unconditionally unpinning pages here, if pages_count wasn't dropped to 0, we will go negative.
With that fixed:
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Ah yes, thanks. That was a leftover from an earlier version...
/Thomas
