Bug 1744979 - Update chunk metadata correctly when decommitting empty chunks in response to out of memory r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D133216

js/src/gc/Heap.cpp

@@ -382,7 +382,8 @@ bool TenuredChunk::decommitOneFreePage(GCRuntime* gc, size_t pageIndex,
   bool ok;
   {
     AutoUnlockGC unlock(lock);
-    ok = MarkPagesUnusedSoft(pageAddress(pageIndex), PageSize);
+    ok = !oom::ShouldFailWithOOM() &&
+         MarkPagesUnusedSoft(pageAddress(pageIndex), PageSize);
   }
 
   // Mark the page as decommited if successful or restore the original free
@@ -423,6 +424,11 @@ void TenuredChunk::decommitFreeArenasWithoutUnlocking(const AutoLockGC& lock) {
     }
 
     decommittedPages[i] = true;
+    for (size_t j = 0; j < ArenasPerPage; ++j) {
+      size_t arenaIndex = i * ArenasPerPage + j;
+      MOZ_ASSERT(freeCommittedArenas[arenaIndex]);
+      freeCommittedArenas[arenaIndex] = false;
+    }
     info.numArenasFreeCommitted -= ArenasPerPage;
   }