Avoid updating class loaders outside system weaks
We update all system weaks using Runtime::SweepSystemWeaks(). But when
we are tracing, we attempt to update them again via
ClassLinker::VisitRoots, which results in double updation of GC-root.
This is not tolerated by userfaultfd-GC as we do in-place sliding
compaction.
Bug: 250480435
Test: art/test/testrunner/testrunner.py --host --gcstres -t
2240-tracing-non-invokable-method
Change-Id: I970f2d47270837f7b02f34d34ae434ba8a4edd2b
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index f487e56..67a20a8 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -2146,9 +2146,18 @@
boot_class_table_->VisitRoots(root_visitor);
// If tracing is enabled, then mark all the class loaders to prevent unloading.
if ((flags & kVisitRootFlagClassLoader) != 0 || tracing_enabled) {
- for (const ClassLoaderData& data : class_loaders_) {
- GcRoot<mirror::Object> root(GcRoot<mirror::Object>(self->DecodeJObject(data.weak_root)));
- root.VisitRoot(visitor, RootInfo(kRootVMInternal));
+ gc::Heap* const heap = Runtime::Current()->GetHeap();
+ // Don't visit class-loaders if compacting with userfaultfd GC as these
+ // weaks are updated using Runtime::SweepSystemWeaks() and the GC doesn't
+ // tolerate double updates.
+ if (!gUseUserfaultfd
+ || !heap->MarkCompactCollector()->IsCompacting(self)) {
+ for (const ClassLoaderData& data : class_loaders_) {
+ GcRoot<mirror::Object> root(GcRoot<mirror::Object>(self->DecodeJObject(data.weak_root)));
+ root.VisitRoot(visitor, RootInfo(kRootVMInternal));
+ }
+ } else {
+ DCHECK_EQ(heap->CurrentCollectorType(), gc::CollectorType::kCollectorTypeCMC);
}
}
} else if (!gUseReadBarrier && (flags & kVisitRootFlagNewRoots) != 0) {