Whilst preparing a second blog post about network namespaces I stumbled across a really strange bug:

Whenever one starts LibreOffice (with the OpenCL-options activated) the command “lsns” stops producing output. Not funny, as one may consider namespaces and operations investigating the namespace settings for Linux processes security relevant. So, I looked a bit into it …

“strace” led me to processes which were Nvidia related. Actually, on my Linux PC, I use the proprietary Nvidia driver 384.98 for my graphics card. The cause behind the trouble with LibreOffice is that the OpenCL-options of LO trigger loading the kernel module “nvidia_uvm”. This module supports CUDA operations – which seem to be used by some recent versions Linux programs as LO and also GIMP.

However, as soon as “nvidia_uvm” is loaded the command “lsns” stops producing output. This should not happen as “lsns” uses standard kernel interfaces for investigating process properties …???…

I have no remedy for this – and am waiting for an answer from the Nvidia developer forum. But at least in case of LibreOffice you can avoid this irritating bug by unsetting the OpenCL options ….