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

[Ryan Novosielski]

To provide a small bit of followup (let me know if what you’ve found disagrees), it looks like this package gets installed/is required by elfutils-libs, which we don’t have on our stateless nodes. So even updating userland in this case wouldn’t necessarily have done it.

> On Jan 12, 2018, at 10:42 AM, Ryan Novosielski <novosirj at rutgers.edu> wrote:
> 
> Thanks — that’s exactly what I did (should have said that) because of a problem some other component was causing with our NFS mounts on our stateless nodes and I’ve not tracked that down yet.
> 
> This does indeed solve the problem.
> 
> On Jan 12, 2018, at 04:15, Götz Waschk <goetz.waschk at gmail.com> wrote:
> 
>> 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
>> 
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