Discussed this a bit with Chris, I think a comment here is warranted
that this will be bad once we have more than one i915 instance. And
lockdep won't catch it.
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 74da35611d7c..70dc506a5426 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -135,6 +135,12 @@ userptr_mn_invalidate_range_start(struct mmu_notifier *_mn,
switch (mutex_trylock_recursive(unlock)) {
default:
case MUTEX_TRYLOCK_FAILED:
+ /*
+ * NOTE: This only works because there's only
+ * ever one i915-style struct_mutex in the
+ * entire system. If we could have two i915
+ * instances, this would deadlock.
+ */
if (mutex_lock_killable_nested(unlock, I915_MM_SHRINKER)) {
i915_gem_object_put(obj);
return -EINTR;
--
2.22.0
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