The panic on http://prestodb.rocks/code/simd/ seems to be different from the case in bug 1375902. At least it's a different cause. #12 0x00007fffe7ec76d5 in geckoservo::glue::Servo_TraverseSubtree (root=0x7fffb46877d0, raw_data=0x7fffacfa1000, snapshots=0x7fffacd7ee48, root_behavior=Normal, restyle_behavior=Normal) at /home/ikezoe/central/servo/ports/geckolib/glue.rs:306 #13 0x00007fffe3d99401 in mozilla::ServoStyleSet::PrepareAndTraverseSubtree (this=0x7fffacdc5740, aRoot=0x7fffb46877d0, aRootBehavior=mozilla::TraversalRootBehavior::Normal, aRestyleBehavior=mozilla::TraversalRestyleBehavior::Normal) at /home/ikezoe/central/layout/style/ServoStyleSet.cpp:446 #14 0x00007fffe3d9b9ec in mozilla::ServoStyleSet::StyleNewSubtree (this=0x7fffacdc5740, aRoot=0x7fffb46877d0) at /home/ikezoe/central/layout/style/ServoStyleSet.cpp:1024 #15 0x00007fffe3fb74b2 in nsCSSFrameConstructor::GetAnonymousContent (this=0x7fffc819d220, aParent=0x7fffb2a8f2c0, aParentFrame=0x7fffb468c7e0, aContent=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:4362 #16 0x00007fffe3fb7a89 in nsCSSFrameConstructor::BeginBuildingScrollFrame (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a8f2c0, aContentStyle=0x7fffab590940, aParentFrame=0x7fffb468c538, aScrolledPseudo=0x7fffd46ef070, aIsRoot=false, aNewFrame=@0x7fffffff7c10: 0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:4672 #17 0x00007fffe3fb8441 in nsCSSFrameConstructor::ConstructScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468c538, aDisplay=0x7fffc2f4aa18, aFrameItems=..., aConstructor=0x7fffe406ed71 <NS_NewBlockFormattingContext(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:4987 #18 0x00007fffe3fb837c in nsCSSFrameConstructor::ConstructScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468c538, aDisplay=0x7fffc2f4aa18, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:4970 #19 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffb468c538, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #20 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffb468c538, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #21 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffb468c538, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #22 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a8f230, aStyleContext=0x7fffb4692080, aFrame=0x7fffb468c538, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffb468c538) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #23 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a8f230, aParentFrame=0x7fffb468bf80, aContentParentFrame=0x7fffb468bf80, aStyleContext=0x7fffb4692080, aNewFrame=0x7fffffff8468, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x7fffb468c538, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #24 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468bf80, aDisplay=0x7fffc2fd8868, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) ---Type <return> to continue, or q <return> to quit--- at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #25 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468bf80, aDisplay=0x7fffc2fd8868, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 #26 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffb468bf80, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #27 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffb468bf80, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #28 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffb468bf80, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #29 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6df70, aStyleContext=0x7fffab577a40, aFrame=0x7fffb468bf80, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffb468bf80) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #30 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6df70, aParentFrame=0x7fffb468b778, aContentParentFrame=0x7fffb468b778, aStyleContext=0x7fffab577a40, aNewFrame=0x7fffffff8c98, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x0, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #31 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468b778, aDisplay=0x7fffc2f47fe8, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #32 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468b778, aDisplay=0x7fffc2f47fe8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 #33 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffb468b778, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #34 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffb468b778, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #35 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffb468b778, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #36 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6dca0, aStyleContext=0x7fffab577880, aFrame=0x7fffb468b778, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffb468b778) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #37 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6dca0, aParentFrame=0x7fffb468b4c0, aContentParentFrame=0x7fffb468b4c0, aStyleContext=0x7fffab577880, aNewFrame=0x7fffffff94c8, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x0, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #38 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468b4c0, aDisplay=0x7fffc2f47778, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #39 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468b4c0, aDisplay=0x7fffc2f47778, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 #40 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffb468b4c0, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #41 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffb468b4c0, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #42 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffb468b4c0, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #43 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6da60, aStyleContext=0x7fffb468f5c0, ---Type <return> to continue, or q <return> to quit--- aFrame=0x7fffb468b4c0, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffb468b4c0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #44 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6da60, aParentFrame=0x7fffb468a840, aContentParentFrame=0x7fffb468a840, aStyleContext=0x7fffb468f5c0, aNewFrame=0x7fffffff9cf8, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x0, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #45 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468a840, aDisplay=0x7fffc2f46f08, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #46 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffb468a840, aDisplay=0x7fffc2f46f08, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 #47 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffb468a840, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #48 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffb468a840, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #49 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffb468a840, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #50 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6d040, aStyleContext=0x7fffb468f340, aFrame=0x7fffb468a840, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffb468a840) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #51 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6d040, aParentFrame=0x7fffab6e39a8, aContentParentFrame=0x7fffab6e39a8, aStyleContext=0x7fffb468f340, aNewFrame=0x7fffffffa528, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x0, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #52 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffab6e39a8, aDisplay=0x7fffc2f46338, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #53 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffab6e39a8, aDisplay=0x7fffc2f46338, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 #54 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffab6e39a8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #55 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffab6e39a8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #56 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffab6e39a8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #57 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6c980, aStyleContext=0x7fffb468f200, aFrame=0x7fffab6e39a8, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffab6e39a8) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #58 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb2a6c980, aParentFrame=0x7fffab6e38f8, aContentParentFrame=0x7fffab6e38f8, aStyleContext=0x7fffb468f200, aNewFrame=0x7fffffffad58, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x0, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #59 0x00007fffe3fb87b9 in nsCSSFrameConstructor::ConstructNonScrollableBlockWithConstructor (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffab6e38f8, aDisplay=0x7ffface46d58, aFrameItems=..., aConstructor=0x7fffe406ed2e <NS_NewBlockFrame(nsIPresShell*, nsStyleContext*)>) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5061 #60 0x00007fffe3fb8616 in nsCSSFrameConstructor::ConstructNonScrollableBlock (this=0x7fffc819d220, aState=..., aItem=..., aParentFrame=0x7fffab6e38f8, aDisplay=0x7ffface46d58, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:5022 ---Type <return> to continue, or q <return> to quit--- #61 0x00007fffe3fb5e20 in nsCSSFrameConstructor::ConstructFrameFromItemInternal (this=0x7fffc819d220, aItem=..., aState=..., aParentFrame=0x7fffab6e38f8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:3971 #62 0x00007fffe3fbc11f in nsCSSFrameConstructor::ConstructFramesFromItem (this=0x7fffc819d220, aState=..., aIter=..., aParentFrame=0x7fffab6e38f8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:6342 #63 0x00007fffe4013e34 in nsCSSFrameConstructor::ConstructFramesFromItemList (this=0x7fffc819d220, aState=..., aItems=..., aParentFrame=0x7fffab6e38f8, aFrameItems=...) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:10971 #64 0x00007fffe3fc8ca3 in nsCSSFrameConstructor::ProcessChildren (this=0x7fffc819d220, aState=..., aContent=0x7fffb29a2a80, aStyleContext=0x7fffab9b2f80, aFrame=0x7fffab6e38f8, aCanHaveGeneratedContent=true, aFrameItems=..., aAllowBlockStyles=true, aPendingBinding=0x0, aPossiblyLeafFrame=0x7fffab6e38f8) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:11279 #65 0x00007fffe3fcb662 in nsCSSFrameConstructor::ConstructBlock (this=0x7fffc819d220, aState=..., aContent=0x7fffb29a2a80, aParentFrame=0x7fffab6e30a8, aContentParentFrame=0x7fffab6e30a8, aStyleContext=0x7fffab9b2f80, aNewFrame=0x7fffffffb590, aFrameItems=..., aPositionedFrameForAbsPosContainer=0x7fffab6e38f8, aPendingBinding=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:12287 #66 0x00007fffe3fb23e2 in nsCSSFrameConstructor::ConstructDocElementFrame (this=0x7fffc819d220, aDocElement=0x7fffb29a2a80, aFrameState=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:2721 #67 0x00007fffe3fc0c97 in nsCSSFrameConstructor::ContentRangeInserted (this=0x7fffc819d220, aContainer=0x0, aStartChild=0x7fffb29a2a80, aEndChild=0x0, aFrameState=0x0, aAllowLazyConstruction=false, aForReconstruction=false, aProvidedTreeMatchContext=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:8028 #68 0x00007fffe3f8ea9a in nsCSSFrameConstructor::ContentRangeInserted (this=0x7fffc819d220, aContainer=0x0, aStartChild=0x7fffb29a2a80, aEndChild=0x0, aFrameState=0x0, aAllowLazyConstruction=false, aProvidedTreeMatchContext=0x0) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.h:277 #69 0x00007fffe3fc072b in nsCSSFrameConstructor::ContentInserted (this=0x7fffc819d220, aContainer=0x0, aChild=0x7fffb29a2a80, aFrameState=0x0, aAllowLazyConstruction=false) at /home/ikezoe/central/layout/base/nsCSSFrameConstructor.cpp:7913 #70 0x00007fffe3f59869 in mozilla::PresShell::Initialize (this=0x7fffacf9c000, aWidth=66200, aHeight=36600) at /home/ikezoe/central/layout/base/PresShell.cpp:1796 #71 0x00007fffe1a514c4 in nsContentSink::StartLayout (this=0x7fffacdad400, aIgnorePendingSheets=false) at /home/ikezoe/central/dom/base/nsContentSink.cpp:1227

Cameron is going to take a look at this.

Will be fixed by the patch for bug 1374175.

I've changed the approach to fix bug 1374175, so it will not cover this bug. Unlike bug 1374175, a problematic reconstruction damage comes from here [1]. [1] https://hg.mozilla.org/mozilla-central/file/6f8f10f48ace/servo/components/style/matching.rs#l1587

Fixed by bug 1376352.

Verified in comment 4. (Marked as verified for better overview in stylo-site-issues because of bug 1375983 comment 5.)