[mvapich-discuss] "CMA is not available. Set MV2_SMP_USE_CMA=0" error w/MVAPICH2 2.2 after kernel update?

[Götz Waschk]

On Fri, Jan 12, 2018 at 4:52 AM, Ryan Novosielski <novosirj at rutgers.edu> wrote:
> Our site has recently upgraded our kernel from 3.10.0-229.20.1 to 3.10.0-693.11.1 and suddenly I’ve started seeing "CMA is not available. Set MV2_SMP_USE_CMA=0 to disable CMA.” with our copy of MVAPICH2 2.2 that we’ve been using for some time. This doesn’t make a lot of sense to me, given that all versions of 3.10.x are newer than the 3.2 that should be required for this feature.


Dear Ryan,

I stumbled upon the same problem. It happened after upgrading the
kernel to the one based on EL7.4 without the matching userland
components. Take a look at elfutils-default-yama-scope. It does set
the sysctl kernel.yama.ptrace_scope to 0.

This is a new security feature backported to the 693 kernel that is
disabled by default in this userland component. It prevents CMA as
processes are forbidden to use ptrace on processes other than their
child processes.

HTH, Götz Waschk