Can CUDA and CPU share the same memory through nvscibuf

I created a nvscibuf obj, and I can get the cpu pointer(through API: NvSciBufObjGetCpuPtr) and gpu pointer(through API: NvSciBufObjGetCpuPtr). I used the gpu pointer to create a GpuMat(example: cv::cuda::GpuMat gpu_img(height, width, CV_8UC1, gpu_ptr), and I wrote data to this gpu_img(example:cv::cuda::cvtColor(src, gpu_img, cv::COLOR_BGR2GRAY, 0)).

I download the data to cpu from gpu pointer and print them, it semms good. However, when I try to directly print data with the cpu pointer, there are some zero values and the results varied at each execution.I suspected that it had something to do with cache.

However, I resized the image from 960x540 to 4096x1080, the data from cpu became normal, I suspected that it had something to do with padding.