Bug 157462 – ThreadSanitizer: Data race in WebCore::ScrollingThread::initializeRunLoop

• Component: WebCore Misc.
• Status: CLOSED INVALID

[David Kilzer (:ddkilzer)]

ThreadSanitizer has found a data race and thread leak in WebCore::ScrollingThread::createThreadIfNeeded while running layout tests:

CRASHING TEST: compositing/layer-creation/translate-scale-animation-overlap.html
==65095==
==================
WARNING: ThreadSanitizer: data race (pid=65095)
  Write of size 8 at 0x000110863150 by thread T12:
    #0 WebCore::ScrollingThread::initializeRunLoop() <null> (WebCore+0x00000174e78e)
    #1 WebCore::ScrollingThread::threadCallback(void*) <null> (WebCore+0x00000174e0f0)
    #2 WTF::threadEntryPoint(void*) <null> (JavaScriptCore+0x000000a06801)
 
  Previous read of size 8 at 0x000110863150 by main thread:
    #0 WebCore::ScrollingThread::createThreadIfNeeded() <null> (WebCore+0x00000174de3b)
    #1 WebCore::ScrollingThread::dispatch(std::__1::function<void ()>) <null> (WebCore+0x00000174dc2a)
    #2 WebCore::MemoryPressureHandler::releaseMemory(WebCore::Critical, WebCore::Synchronous) <null> (WebCore+0x0000012d3c93)
    #3 std::__1::__function::__func<WebCore::MemoryPressureHandler::MemoryPressureHandler()::$_0, std::__1::allocator<WebCore::MemoryPressureHandler::MemoryPressureHandler()::$_0>, void (WebCore::Critical, WebCore::Synchronous)>::operator()(WebCore::Critical&&, WebCore::Synchronous&&) <null> (WebCore+0x0000012d40a9)
    #4 WebCore::MemoryPressureHandler::respondToMemoryPressure(WebCore::Critical, WebCore::Synchronous) <null> (WebCore+0x0000012d4c26)
    #5 invocation function for block in WebCore::MemoryPressureHandler::install() <null> (WebCore+0x0000012d4b60)
    #6 __wrap_dispatch_source_set_event_handler_block_invoke <null> (libclang_rt.tsan_osx_dynamic.dylib+0x00000005c7e2)
 
  Location is global 'WebCore::ScrollingThread::singleton()::scrollingThread' at 0x000110863138 (WebCore+0x0000020d1150)
 
  Thread T12 (tid=1603665, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib+0x0000000230c1)
    #1 WTF::createThreadInternal(void (*)(void*), void*, char const*) <null> (JavaScriptCore+0x000000a06b4d)
    #2 WebCore::ScrollingThread::dispatch(std::__1::function<void ()>) <null> (WebCore+0x00000174dc2a)
    #3 WebCore::MemoryPressureHandler::releaseMemory(WebCore::Critical, WebCore::Synchronous) <null> (WebCore+0x0000012d3c93)
    #4 std::__1::__function::__func<WebCore::MemoryPressureHandler::MemoryPressureHandler()::$_0, std::__1::allocator<WebCore::MemoryPressureHandler::MemoryPressureHandler()::$_0>, void (WebCore::Critical, WebCore::Synchronous)>::operator()(WebCore::Critical&&, WebCore::Synchronous&&) <null> (WebCore+0x0000012d40a9)
    #5 WebCore::MemoryPressureHandler::respondToMemoryPressure(WebCore::Critical, WebCore::Synchronous) <null> (WebCore+0x0000012d4c26)
    #6 invocation function for block in WebCore::MemoryPressureHandler::install() <null> (WebCore+0x0000012d4b60)
    #7 __wrap_dispatch_source_set_event_handler_block_invoke <null> (libclang_rt.tsan_osx_dynamic.dylib+0x00000005c7e2)
 
SUMMARY: ThreadSanitizer: data race (OpenSource/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x174e78e) in WebCore::ScrollingThread::initializeRunLoop()
==================
==================
WARNING: ThreadSanitizer: thread leak (pid=65095)
  Thread T10 (tid=1603424, finished) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib+0x0000000230c1)
    #1 WTF::createThreadInternal(void (*)(void*), void*, char const*) <null> (JavaScriptCore+0x000000a06b4d)
 
SUMMARY: ThreadSanitizer: thread leak (OpenSource/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0xa06b4d) in WTF::createThreadInternal(void (*)(void*), void*, char const*)
==================
ThreadSanitizer: reported 2 warnings

[David Kilzer (:ddkilzer)]

<rdar://problem/26157286>

[David Kilzer (:ddkilzer)]

Created attachment 278361 [details]
Patch v1

[Darin Adler]

Comment on attachment 278361 [details]
Patch v1

Seems a little bit messy the way this function combines Mac-specific code, some of which is guarded by #if PLATFORM(COCOA) and some of which is not, with platform independent code.

[WebKit Commit Bot]

Comment on attachment 278361 [details]
Patch v1

Clearing flags on attachment: 278361

Committed r200554: <http://trac.webkit.org/changeset/200554>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[David Kilzer (:ddkilzer)]

Rolled out r200554 in r200561.

Committed r200561: <http://trac.webkit.org/changeset/200561>

Turns out the thread leak is for a separate issue (that reproduces when using --run-singly with "run-webkit-tests -1").

This issue is about a data race in WebCore::ScrollingThread::initializeRunLoop.

[David Kilzer (:ddkilzer)]

Yep, this was a false positive due to use of bmalloc.  Adding --additional-env-var=“Malloc=1” to the run-webkit-tests invocation makes these false positives go away.

[Alexey Proskuryakov]

blame has an explicit check for injected ASan library, we should add the same for TSan.