UCX_1.5.1 and process_vm_readv delivered 0 instead of ....

[spikebike]

On an ubuntu-18.04 system I built openmpi-4.0.1 with UCX-1.5.1. Many codes on a single node or multiple node runs "just worked". However some codes like LAMMPs or ESKM would report errors like:

process_vm_readv delivered 0 instead of 480960, error message Operation not permitted

The immediate fix is:
sysctl -w kernel.yama.ptrace_scope=0

The permanent fix is to make the same change in /etc/sysctl.d/10-ptrace.conf, which will fix things after the next boot.

I didn't see any mention of this in the docs, by ./configure, during ./install, or at runtime.

[yosefe]

@spikebike the issue is fixed in #3205 which will be part of ucx v1.6 release