On 17/03/14 17:59, Karl Pielorz wrote:
> I setup a VM a while ago under XenServer 6.2 - it's an amd64 FBSD 10.0-S
> box (based on r261289) - it's running under Xen PVHVM.
> I set it up - and left it for a while (46 days). I went to ssh to it
> today, and got:
> ssh_exchange_identification: Connection closed by remote host
> Getting on to the boxes console there's lots of what look to be 'stuck'
> sshd processes?
> 0 3933 895 0 20 0 84868 6944 urdlck Is - 0:00.01 sshd: unknown
> [priv] (sshd)
> 22 3934 3933 0 20 0 0 0 - Z - 0:00.00 <defunct>
> 0 3935 3933 0 20 0 84868 6952 sbwait I - 0:00.00 sshd: unknown
> [pam] (sshd)
> 0 4338 895 0 20 0 84868 6944 urdlck Is - 0:00.01 sshd: unknown
> [priv] (sshd)
> 22 4339 4338 0 20 0 0 0 - Z - 0:00.00 <defunct>
> Anyone know what 'urdlck' is?
It seems like the process is stuck while trying to acquire a rw mutex in
read mode. Could you obtain a backtrace of the process with gdb? Also a
kernel-space dump might be useful, could you also run procstat -k <pid>?
> There's 126 of these processes, e.g.
> 5446 - I 0:00.00 sshd: unknown [pam] (sshd)
> 5450 - Is 0:00.01 sshd: unknown [priv] (sshd)
> 5452 - I 0:00.00 sshd: unknown [pam] (sshd)
> 5453 - Is 0:00.01 sshd: unknown [priv] (sshd)
> Bearing in mind the box is firewalled from ssh access, and no one (apart
> from me today) has attempted to get onto the box with ssh - this is a
> little concerning. Every about 5-10 connects will actually 'connect' -
> the rest just result in the 'key exchange' error.
> Kernel is GENERIC with:
> options NO_ADAPTIVE_MUTEXES
> options NO_ADAPTIVE_RWLOCKS
> options NO_ADAPTIVE_SX
> There's nothing logged in dmesg, or syslog.
> Is there anything worth doing to this VM before I restart it - i.e. to
> try and figure out what's happened? / troubleshoot?
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