Skip site navigation (1)Skip section navigation (2)
Date:      Sat, 22 Jun 2002 01:51:46 -0700 (PDT)
From:      Patrick Thomas <root@utility.clubscholarship.com>
To:        Nielsen <nielsen@memberwebs.com>
Cc:        <hackers@freebsd.org>
Subject:   Re: (jail) problem and a (possible) solution ?
Message-ID:  <20020622014826.U68572-100000@utility.clubscholarship.com>
In-Reply-To: <200206220652.g5M6qOV84476@utility.clubscholarship.com>

next in thread | previous in thread | raw e-mail | index | archive | help

What it does is the userland hangs, but the kernel keeps running.

When the system is crashed, I can still ping it successfully, and I can
still open sockets (like I can open a connection to a jails httpd or sshd,
or the sshd of the underlying server itself) but nothing answers on the
sockets - they just hang open.

So everything stops running, but it is still "up" - still responds to
pings...syslog stops logging though, cron stops running....

Two questions for you:

1) do you allow them write access to their /dev/mem, /dev/kmem, /dev/io ?

2) does this sound like what you see?  Can you still ping the crashed
server ?

I'm mostly just curious if this kind of crash (userland hung but kernel
running) is a possible outcome of someone in a jail fiddling with those
/dev nodes, or if fiddling with dev/mem or /dev/kmem or io would just lock
the machine up hard and completely.

Terry?

--PT



On Fri, 21 Jun 2002, Nielsen wrote:

> Yes I've had the same problem. One system runs just fine with it's jails,
> and another crashes habitually. It has to do with a certain jail (and
> services). Our system are set up to be able to move jails between them
> (great for backups and near perfect uptime), and a certain set of jails
> always hangs the system in this way. I'm trying to narrow it down. Do you
> get a core dump or does it just hang?
>
> Nate
>
> ----- Original Message -----
> From: "Patrick Thomas" <root@utility.clubscholarship.com>
> To: <hackers@freebsd.org>
> Sent: Friday, June 21, 2002 16:43
> Subject: (jail) problem and a (possible) solution ?
>
>
> >
> > A test server of mine running a number of jails keeps locking up - but the
> > odd thing about the lockup is that the userland stops, but the kernel
> > keeps running
> >
> > (sockets can be opened, but the servers never respond on them, the machine
> > still responds to pings, but logs show that all real activity stops)
> >
> > I just noticed today that some jails still have writable /dev/mem and
> > /dev/kmem and /dev/io nodes.  I think it is plausable that some kind of
> > fiddling (writing) to these nodes is causing this kind of lockup.
> >
> > ----
> >
> > Is this assumption reasonable, or if some jail user fiddled with their
> > /dev/mem or /dev/kmem or /dev/io node would it just totally crash out the
> > machine and I _wouldn't_ still be able to ping the server after it crashes
> > ?
> >
> > thanks,
> >
> > PT
> >
> >
> > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > with "unsubscribe freebsd-hackers" in the body of the message
> >
>
>


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020622014826.U68572-100000>