On 9/22/2015 2:16 PM, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Prevent leaking VMAs and PPGTT VMs when objects are imported
via flink.
Scenario is that any VMAs created by the importer will be left
dangling after the importer exits, or destroys the PPGTT context
with which they are associated.
This is caused by object destruction not running when the
importer closes the buffer object handle due the reference held
by the exporter. This also leaks the VM since the VMA has a
reference on it.
In practice these leaks can be observed by stopping and starting
the X server on a kernel with fbcon compiled in. Every time
X server exits another VMA will be leaked against the fbcon's
frame buffer object.
Also on systems where flink buffer sharing is used extensively,
like Android, this leak has even more serious consequences.
This version is takes a general approach from the earlier work
by Rafael Barabalho (drm/i915: Clean-up PPGTT on context
^Barbalho
destruction) and tries to incorporate the subsequent discussion
between Chris Wilson and Daniel Vetter.
v2:
Removed immediate cleanup on object retire - it was causing a
recursive VMA unbind via i915_gem_object_wait_rendering. And
it is in fact not even needed since by definition context
cleanup worker runs only after the last context reference has
been dropped, hence all VMAs against the VM belonging to the
context are already on the inactive list.
v3:
Previous version could deadlock since VMA unbind waits on any
rendering on an object to complete. Objects can be busy in a
different VM which would mean that the cleanup loop would do
the wait with the struct mutex held.
This is an even simpler approach where we just unbind VMAs
without waiting since we know all VMAs belonging to this VM
are idle, and there is nothing in flight, at the point
context destructor runs.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Testcase: igt/gem_ppgtt.c/flink-and-exit-vma-leak
I guess we'll have to wait a bit more to have a fix for
flink-and-close-vma-leak subtest... Anyway, this addresses the flink
leak (also seen in bug 87729 - igt/gem_close_race)
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Rafael Barbalho <rafael.barbalho@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 5 +++++
drivers/gpu/drm/i915/i915_gem.c | 20 ++++++++++++++++----
drivers/gpu/drm/i915/i915_gem_context.c | 24 ++++++++++++++++++++++++
3 files changed, 45 insertions(+), 4 deletions(-)
@@ -3274,6 +3276,16 @@ int i915_vma_unbind(struct i915_vma *vma)
return 0;
}
+int i915_vma_unbind(struct i915_vma *vma)
+{
+ return __i915_vma_unbind(vma, true);
+}
+
+int _i915_vma_unbind_no_wait(struct i915_vma *vma)
^ it needs one more underscore (__i915_vma_unbind_no_wait).
+{
+ return __i915_vma_unbind(vma, false);
+}
+
Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx>
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