bmalloc: Improved alignment in LargeChunk

https://bugs.webkit.org/show_bug.cgi?id=131895

Reviewed by Andreas Kling.

* bmalloc/Chunk.h:
* bmalloc/LargeChunk.h: Align to vmPageSize just like Chunk does.
Technically, the previous alignment was harmless, but I would prefer,
dear reader, not to have to explain the interlocking set of
circumstances that made it so.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@167554 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/Source/bmalloc/ChangeLog b/Source/bmalloc/ChangeLog
index 61b86c5419d30c1392f3d2116005ed3d67fea460..2e6472c5e1a34232b1f69619e7c7bdf01bc69d4f 100644 (file)
--- a/Source/bmalloc/ChangeLog
+++ b/Source/bmalloc/ChangeLog
@@ -1,3 +1,16 @@
+2014-04-19  Geoffrey Garen  <ggaren@apple.com>
+
+        bmalloc: Improved alignment in LargeChunk
+        https://bugs.webkit.org/show_bug.cgi?id=131895
+
+        Reviewed by Andreas Kling.
+
+        * bmalloc/Chunk.h:
+        * bmalloc/LargeChunk.h: Align to vmPageSize just like Chunk does.
+        Technically, the previous alignment was harmless, but I would prefer,
+        dear reader, not to have to explain the interlocking set of
+        circumstances that made it so.
+
 2014-04-19  Geoffrey Garen  <ggaren@apple.com>
 
         Rolled out r167502 because it caused a crash on the facebook benchmark.

diff --git a/Source/bmalloc/bmalloc/Chunk.h b/Source/bmalloc/bmalloc/Chunk.h
index b05c5ceae8cc5ea404184e1db3b8ee98f31989f0..8b9d5612f6942b9b67acafe88454c6ebe271da83 100644 (file)
--- a/Source/bmalloc/bmalloc/Chunk.h
+++ b/Source/bmalloc/bmalloc/Chunk.h
@@ -62,8 +62,8 @@ private:
     Page m_pages[pageCount];
 
     // Align to vmPageSize to avoid sharing physical pages with metadata.
-    // Otherwise, we'll confuse the scavenger into scavenging metadata.
-     alignas(vmPageSize) char m_memory[];
+    // Otherwise, we'll confuse the scavenger into trying to scavenge metadata.
+    alignas(vmPageSize) char m_memory[];
 };
 
 template<class Traits>

diff --git a/Source/bmalloc/bmalloc/LargeChunk.h b/Source/bmalloc/bmalloc/LargeChunk.h
index c011e76a09a826ebd55b0224d8967d9f9948e1c0..d0027941490634f9886d7e0a692e9b8a9bf1360c 100644 (file)
--- a/Source/bmalloc/bmalloc/LargeChunk.h
+++ b/Source/bmalloc/bmalloc/LargeChunk.h
@@ -64,7 +64,10 @@ private:
     // We use the X's for boundary tags and the O's for edge sentinels.
 
     BoundaryTag m_boundaryTags[boundaryTagCount];
-    alignas(largeAlignment) char m_memory[];
+
+    // Align to vmPageSize to avoid sharing physical pages with metadata.
+    // Otherwise, we'll confuse the scavenger into trying to scavenge metadata.
+    alignas(vmPageSize) char m_memory[];
 };
 
 inline LargeChunk* LargeChunk::create()