su: cannot set user id: Resource temporarily unavailable

[Ken D'Ambrosio]

On 2014-03-10 10:05, 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 ~]$


This is where, when desperate, I whip out "strace":

strace -s 1024 -f -o /tmp/sudo_strace.log sudo su - user2

This will generate a logfile with all the system calls made by the 
command; it takes some practice to parse strace output reliably, as 
there are a bunch of red herrings, e.g.,

3490  access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or 
directory)

Which is another way of saying "The file /etc/ld.so.preload doesn't 
exist -- though it may or may not be optional."  I would dive into the 
bottom of the log file, then search backward for your error string; from 
that, I'd look backward for something that *isn't* a red herring.

strace is a wonderful tool, but it's a bit like a sledgehammer for 
flyswatting, and I only break it out when I'm completely stumped.

Good luck!

-Ken


> 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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