Trial: build trunk with Oilpan everywhere.

third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp

Index: third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp b/third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp
index ad829bc1d99588bb8d620d421d18e290daaddfbe..28cdafbcc5cf0cf445b88c2f06f576113bbd5df7 100644
--- a/third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp
+++ b/third_party/WebKit/Source/core/css/CSSDefaultStyleSheets.cpp
@@ -46,7 +46,8 @@ using namespace HTMLNames;
 
 CSSDefaultStyleSheets& CSSDefaultStyleSheets::instance()
 {
-    DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<CSSDefaultStyleSheets>, cssDefaultStyleSheets, (adoptPtrWillBeNoop(new CSSDefaultStyleSheets())));
+    WTF_ANNOTATE_SCOPED_MEMORY_LEAK;
+    DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<CSSDefaultStyleSheets>, cssDefaultStyleSheets, (adoptPtrWillBeNoop(new CSSDefaultStyleSheets)));

[haraken, 2015/11/30 01:48:47]

What happens if we insert WTF_ANNOTATE_SCOPED_MEMORY_LEAK into
DEFINE_STATIC_LOCAL (and its family)? I guess it would be reasonable to mark all
DEFINE_STATIC_LOCALs as leaking.

[sof, 2015/11/30 21:53:39]

I think it will mostly be non-harmful, with or without Oilpan, but it isn't
sufficient to solve the problem for Oilpan.

The reason why is that Oilpan heap pages are registered root regions to LSan,
meaning that the leak detector will scan those regions for pointers into other
heaps (e.g., PartitionAlloc's) and check if those pointed-to objects are
LSan-controlled allocations. If they are, we've got a leak.

Which means it will be able to scan some of the stylesheet heap objects that
instance() retains and refers to, and from those locate their off-heap &
LSan-controlled allocations. So, if we just use WTF_ANNOTATE_SCOPED_MEMORY_LEAK
when instantiating instance(), only the allocations that the constructor makes
will be exempted from LSan's consideration. e.g., what
instance()::m_defaultSheet initially allocates will not be seen as leaking.

However, any allocation made subsequently and then attached to instance() will
not be exempted from LSan leak detection & will be seen as leaking. e.g.,
instance()::m_defaultViewSourceStyle and all it points will leak if it is ever
lazily created.

Which means we have to turn off LSan whenever we create objects and update a
global singleton Persistent<> to refer to those. Hence all the uses of
WTF_ANNOTATE_SCOPED_MEMORY_LEAK here. Which is a brittle arrangement.

We sort of want LSan to flood fill kIgnored tags from the global
cache/singleton, but that is not what LSan (also) does.

iow, I don't have a good solution or approach to suggest atm.

     return *cssDefaultStyleSheets;
 }
 
@@ -106,6 +107,7 @@ CSSDefaultStyleSheets::CSSDefaultStyleSheets()
 RuleSet* CSSDefaultStyleSheets::defaultViewSourceStyle()
 {
     if (!m_defaultViewSourceStyle) {
+        WTF_ANNOTATE_SCOPED_MEMORY_LEAK;
         m_defaultViewSourceStyle = RuleSet::create();
         // Loaded stylesheet is leaked on purpose.
         RefPtrWillBeRawPtr<StyleSheetContents> stylesheet = parseUASheet(loadResourceAsASCIIString("view-source.css"));
@@ -117,6 +119,7 @@ RuleSet* CSSDefaultStyleSheets::defaultViewSourceStyle()
 RuleSet* CSSDefaultStyleSheets::defaultXHTMLMobileProfileStyle()
 {
     if (!m_defaultXHTMLMobileProfileStyle) {
+        WTF_ANNOTATE_SCOPED_MEMORY_LEAK;
         m_defaultXHTMLMobileProfileStyle = RuleSet::create();
         // Loaded stylesheet is leaked on purpose.
         RefPtrWillBeRawPtr<StyleSheetContents> stylesheet = parseUASheet(loadResourceAsASCIIString("xhtmlmp.css"));
@@ -128,6 +131,7 @@ RuleSet* CSSDefaultStyleSheets::defaultXHTMLMobileProfileStyle()
 RuleSet* CSSDefaultStyleSheets::defaultMobileViewportStyle()
 {
     if (!m_defaultMobileViewportStyle) {
+        WTF_ANNOTATE_SCOPED_MEMORY_LEAK;
         m_defaultMobileViewportStyle = RuleSet::create();
         m_mobileViewportStyleSheet = parseUASheet(loadResourceAsASCIIString("viewportAndroid.css"));
         m_defaultMobileViewportStyle->addRulesFromSheet(m_mobileViewportStyleSheet.get(), screenEval());
@@ -139,6 +143,7 @@ void CSSDefaultStyleSheets::ensureDefaultStyleSheetsForElement(const Element& el
 {
     // FIXME: We should assert that the sheet only styles SVG elements.
     if (element.isSVGElement() && !m_svgStyleSheet) {
+        WTF_ANNOTATE_SCOPED_MEMORY_LEAK;
         m_svgStyleSheet = parseUASheet(loadResourceAsASCIIString("svg.css"));
         m_defaultStyle->addRulesFromSheet(svgStyleSheet(), screenEval());
         m_defaultPrintStyle->addRulesFromSheet(svgStyleSheet(), printEval());