Hi Chris, Thanks for all the info. Below is what can go into the FAQ. Any suggestions?
I'm trying to use the Cross Memory Attach (CMA) capability within the shared-memory (sm) BTL, but am getting: "mca_btl_sm_get_sync: process_vm_readv failed: 1." Why am I seeing this error message? This may be due to insufficient permissions. CMA's usage requirements are exactly the same as those required to successfully perform a ptrace wtih PTRACE_ATTACH. On some systems, a modification to /etc/sysctl.d/10-ptrace.conf is required. Change: kernel.yama.ptrace_scope = 1 to kernel.yama.ptrace_scope = 0 and restart your system so the change can take effect. Thanks, Sam ________________________________________ From: [email protected] [[email protected]] on behalf of Christopher Yeoh [[email protected]] Sent: Thursday, October 18, 2012 5:57 PM To: [email protected] Subject: Re: [OMPI devel] Cross Memory Attach: What am I Missing? 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 > _______________________________________________ > devel mailing list > [email protected]<mailto:[email protected]> > http://www.open-mpi.org/mailman/listinfo.cgi/devel > -- [email protected] _______________________________________________ devel mailing list [email protected] http://www.open-mpi.org/mailman/listinfo.cgi/devel
