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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/204091">204091</a></dd>
<dt>Author</dt> <dd>ggaren@apple.com</dd>
<dt>Date</dt> <dd>2016-08-03 11:43:15 -0700 (Wed, 03 Aug 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>[bmalloc] Merging of XLargeRanges can leak the upper range
https://bugs.webkit.org/show_bug.cgi?id=160403
Reviewed by Michael Saboff.
* bmalloc/Heap.cpp:
(bmalloc::Heap::scavengeLargeObjects): Don't use removePhysical().
Recorded physical size is a performance optimization. It is not the
truth. So it might be zero even if a range contains physical pages.
Instead, iterate each range in the map unconditionally.
The map can shrink when we release the lock, so we must clamp our
iterator each time through the loop.
The map can grow when we release the lock, but we don't care because
growth restarts the scavenger from the beginning.
* bmalloc/XLargeMap.cpp:
(bmalloc::XLargeMap::removePhysical): Deleted. Not used anymore.
* bmalloc/XLargeMap.h:
(bmalloc::XLargeMap::ranges): Added direct access for the sake of
scavengeLargeObjects. (This violates our naming conventions -- I'll do
a rename in a follow-up patch.)</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourcebmallocChangeLog">trunk/Source/bmalloc/ChangeLog</a></li>
<li><a href="#trunkSourcebmallocbmallocHeapcpp">trunk/Source/bmalloc/bmalloc/Heap.cpp</a></li>
<li><a href="#trunkSourcebmallocbmallocXLargeMapcpp">trunk/Source/bmalloc/bmalloc/XLargeMap.cpp</a></li>
<li><a href="#trunkSourcebmallocbmallocXLargeMaph">trunk/Source/bmalloc/bmalloc/XLargeMap.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourcebmallocChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/ChangeLog (204090 => 204091)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/ChangeLog 2016-08-03 18:35:21 UTC (rev 204090)
+++ trunk/Source/bmalloc/ChangeLog 2016-08-03 18:43:15 UTC (rev 204091)
</span><span class="lines">@@ -1,3 +1,31 @@
</span><ins>+2016-08-03 Geoffrey Garen <ggaren@apple.com>
+
+ [bmalloc] Merging of XLargeRanges can leak the upper range
+ https://bugs.webkit.org/show_bug.cgi?id=160403
+
+ Reviewed by Michael Saboff.
+
+ * bmalloc/Heap.cpp:
+ (bmalloc::Heap::scavengeLargeObjects): Don't use removePhysical().
+ Recorded physical size is a performance optimization. It is not the
+ truth. So it might be zero even if a range contains physical pages.
+
+ Instead, iterate each range in the map unconditionally.
+
+ The map can shrink when we release the lock, so we must clamp our
+ iterator each time through the loop.
+
+ The map can grow when we release the lock, but we don't care because
+ growth restarts the scavenger from the beginning.
+
+ * bmalloc/XLargeMap.cpp:
+ (bmalloc::XLargeMap::removePhysical): Deleted. Not used anymore.
+
+ * bmalloc/XLargeMap.h:
+ (bmalloc::XLargeMap::ranges): Added direct access for the sake of
+ scavengeLargeObjects. (This violates our naming conventions -- I'll do
+ a rename in a follow-up patch.)
+
</ins><span class="cx"> 2016-07-13 Enrica Casucci <enrica@apple.com>
</span><span class="cx">
</span><span class="cx"> Update supported platforms in xcconfig files to match the sdk names.
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocHeapcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/Heap.cpp (204090 => 204091)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/Heap.cpp 2016-08-03 18:35:21 UTC (rev 204090)
+++ trunk/Source/bmalloc/bmalloc/Heap.cpp 2016-08-03 18:43:15 UTC (rev 204091)
</span><span class="lines">@@ -131,13 +131,16 @@
</span><span class="cx">
</span><span class="cx"> void Heap::scavengeLargeObjects(std::unique_lock<StaticMutex>& lock, std::chrono::milliseconds sleepDuration)
</span><span class="cx"> {
</span><del>- while (XLargeRange range = m_largeFree.removePhysical()) {
</del><ins>+ auto& ranges = m_largeFree.ranges();
+ for (size_t i = ranges.size(); i-- > 0; i = std::min(i, ranges.size())) {
+ auto range = ranges.pop(i);
+
</ins><span class="cx"> lock.unlock();
</span><span class="cx"> vmDeallocatePhysicalPagesSloppy(range.begin(), range.size());
</span><span class="cx"> lock.lock();
</span><del>-
</del><ins>+
</ins><span class="cx"> range.setPhysicalSize(0);
</span><del>- m_largeFree.add(range);
</del><ins>+ ranges.push(range);
</ins><span class="cx">
</span><span class="cx"> waitUntilFalse(lock, sleepDuration, m_isAllocatingPages);
</span><span class="cx"> }
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocXLargeMapcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/XLargeMap.cpp (204090 => 204091)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/XLargeMap.cpp 2016-08-03 18:35:21 UTC (rev 204090)
+++ trunk/Source/bmalloc/bmalloc/XLargeMap.cpp 2016-08-03 18:43:15 UTC (rev 204091)
</span><span class="lines">@@ -76,16 +76,4 @@
</span><span class="cx"> m_free.push(merged);
</span><span class="cx"> }
</span><span class="cx">
</span><del>-XLargeRange XLargeMap::removePhysical()
-{
- auto it = std::find_if(m_free.begin(), m_free.end(), [](const XLargeRange& range) {
- return range.physicalSize();
- });
-
- if (it == m_free.end())
- return XLargeRange();
-
- return m_free.pop(it);
-}
-
</del><span class="cx"> } // namespace bmalloc
</span></span></pre></div>
<a id="trunkSourcebmallocbmallocXLargeMaph"></a>
<div class="modfile"><h4>Modified: trunk/Source/bmalloc/bmalloc/XLargeMap.h (204090 => 204091)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/bmalloc/bmalloc/XLargeMap.h 2016-08-03 18:35:21 UTC (rev 204090)
+++ trunk/Source/bmalloc/bmalloc/XLargeMap.h 2016-08-03 18:43:15 UTC (rev 204091)
</span><span class="lines">@@ -36,7 +36,7 @@
</span><span class="cx"> public:
</span><span class="cx"> void add(const XLargeRange&);
</span><span class="cx"> XLargeRange remove(size_t alignment, size_t);
</span><del>- XLargeRange removePhysical();
</del><ins>+ Vector<XLargeRange>& ranges() { return m_free; }
</ins><span class="cx">
</span><span class="cx"> private:
</span><span class="cx"> Vector<XLargeRange> m_free;
</span></span></pre>
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