[Intel-gfx] [PATCH 2/2] drm/i915: Remove false assertion in ppgtt_release

[Ben Widawsky]

Originally the thought for the assertion was that if there are no real
VMAs (died during execbuf), or there is only 1 VMA, but the VMA is on
the active list, it's a bug. The former case is pretty obvious. The
later case simply meant to assert the context unref/object retire
interactions were working properly

There is a flaw in the logic of the second when an object has multiple
VMAs. If there are multiple VMAs, it's possible that the object
continually had it's seqno increased as it was used by another context.
In this case, the context ref will die, but the VMA will not be taking
off the active list because of the missing retire seqno for a VMA.

Like some of the other fixes I've submitted recently, this should be
fixed by the eventual work Daniel will do.

This is pretty easy to reproduce whenever mesa uses the blit engine.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem_context.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 1ac648f..2b39fca 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -145,8 +145,7 @@ static int do_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
 
 		do_idle = true;
 		list_for_each_entry(vma, &vm->active_list, mm_list)
-			if (WARN_ON(list_empty(&vma->vma_link) ||
-				    list_is_singular(&vma->vma_link)))
+			if (WARN_ON(list_empty(&vma->vma_link)))
 				break;
 	} else
 		i915_gem_retire_requests(dev);
-- 
2.0.1