Hi Sam,

On Thu, 18 Oct 2012 15:08:59 +0000
"Gutierrez, Samuel K" <[email protected]> wrote:
> 
> I really appreciate your pointing me in the right direction. It turns
> out that on this particular system had /etc/sysctl.d/10-ptrace.conf
> was set to 1. Changing this to 0 fixed the problem. I'm not sure if
> this is the best way of getting things to work, but is sufficient for
> my purposes.

Yes I think this is the best way to do it. The kernel side
implementation of CMA does the same permission checking as as ptrace
(checks to see if PTRACE_MODE_ATTACH would be permitted). A value of 1
in that config file only allows you to ptrace direct child processes,
whereas a 0 removes that restriction. 

You still need to either have CAP_SYS_PTRACE (eg am probably root) or
have the same UID/GID as the target. So from a security point of view
the only extra risk you have exposed your system to are bugs that may
exist in the ptrace or CMA implementations.

Regards,

Chris

> Thanks!
> 
> Sam
> ________________________________
> From: [email protected] [[email protected]] on
> behalf of George Bosilca [[email protected]] Sent: Thursday,
> October 18, 2012 7:44 AM To: Open MPI Developers
> Subject: Re: [OMPI devel] Cross Memory Attach: What am I Missing?
> 
> Check the permissions granted by pam. Look in the /etc/security to
> check for any type of restrictions.
> 
>   george.
> 
> 
> On Oct 17, 2012, at 23:30 , "Gutierrez, Samuel K"
> <[email protected]<mailto:[email protected]>> wrote:
> 
> Hi,
> 
> I'm trying to run with CMA support, but process_vm_readv is failing
> with EPERM when trying to use it as a regular user (everything seems
> to work fine as root). I've looked around for some solutions, but I
> can't seem to find what I'm looking for. The documentation states
> that the target and source processes need to have the same GID and
> UID to work properly. It appears that they do, so my feeling is that
> I'm missing something.
> 
> Any help is greatly appreciated.
> 
> Thanks,
> 
> Sam
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