commit 29472dbb7382bc58b6821e84bfc45ff0b0e360fd
author Ryan Macnak <rmacnak@google.com> Fri Apr 21 19:32:40 2023 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Apr 21 19:32:40 2023 +0000
tree 5f754f50634b83973beb9272fc85b121d5e055ba
parent 81ab76124f425e2ba6e3abaed0cdab97c55fe7b1

[vm, gc] Avoid race between unregistering pages with LSAN and exit.

After the Page is unregistered, the only reference to its VirtualMemory is in memory not traced by LSAN. If exit happens here before the VirtualMemory is deleted or put into the global cache, it appears to be leaked.

TEST=lsan
Bug: https://github.com/dart-lang/sdk/issues/51560
Change-Id: I973e09bb19910d9cdcc3af6c8c9a188f095df36a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/297040
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

runtime/vm/heap/page.cc

diff --git a/runtime/vm/heap/page.cc b/runtime/vm/heap/page.cc
index 3af1136..9bd7595 100644
--- a/runtime/vm/heap/page.cc
+++ b/runtime/vm/heap/page.cc
@@ -136,9 +136,12 @@
 
   free(card_table_);
 
+  // Load before unregistering with LSAN, or LSAN will temporarily think it has
+  // been leaked.
+  VirtualMemory* memory = memory_;
+
   LSAN_UNREGISTER_ROOT_REGION(this, sizeof(*this));
 
-  VirtualMemory* memory = memory_;
   if (CanUseCache(flags_)) {
     ASSERT(memory->size() == kPageSize);
     MutexLocker ml(page_cache_mutex);