su: cannot set user id: Resource temporarily unavailable

[Bruce Dawson]

Check shared memory and semaphores. Its probable that some other
application is swallowing the resource sudo needs. This is a common
method of DOS attacks and 'bot nets.

--Bruce

On Mon, 2014-03-10 at 10:05 -0400, Brian Chabot wrote:
> I'm trying to su to a user on a CentOS 6.4 x86_64 box and get the
> error in the subject:
> 
> [user1 at cent6.4box ~]$ sudo su - user2
> su: cannot set user id: Resource temporarily unavailable
> [user1 at cent6.4box ~]$
> 
> The limits.conf file has the following entries:
> *                                         soft   nofile          100000
> *                                         hard   nofile          100000
> *                                         soft   nproc           8192
> *                                         hard   nproc           32767
> 
> The current usage for pengine is:
> [user1 at cent6.4box ~]$ ps -eLF | grep user2 | wc -l
> 1108
> [user1 at cent6.4box ~]$ lsof | grep user2  | wc -l
> 1558
> [user1 at cent6.4box ~]$
> 
> While these are the majority of the processes and files in use on the
> system, they are nowhere near the limits.
> 
> I even increased the limits 10-fold and that has not worked.
> 
> I'm kind of lost here.  Usually the error indicates files or processes
> over the limit but here... not so much.
> 
> Any ideas?
> 
> 
> 
> Brian Chabot
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