Hi @coincheung,
You should be able to just define  -D_GLIBCXX_USE_CXX11_ABI=0 for your library and you should be fine (in CMake add the line add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)).
More context: the pytorch core library and your extension must be built with the same CXX11 API settings. This used to be _GLIBCXX_USE_CXX11_ABI=1 for older versions ans is =0 now for newer ones. I thought that for a while it was possible to build extensions without setting this flag at all, but it seems it’s explicitly required again.