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Date:      Thu, 24 Feb 2005 14:28:52 +0000 (GMT)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        Dental-on-line <info@dental-on-line.fr>
Cc:        freebsd-bugs@freebsd.org
Subject:   Re: ssh sbwait indfinite timeout on SMP machines
Message-ID:  <Pine.NEB.3.96L.1050224142728.16921A-100000@fledge.watson.org>
In-Reply-To: <421DAE3F.8030103@dental-on-line.fr>

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On Thu, 24 Feb 2005, Dental-on-line wrote:

> We are using two SMP machines (Dell 1750) with 5.3_p2 RELENG and have
> timeout problems with SSH.
> 
> This problem happens ONLY on SMP machines not uniprocessor ones. 

Could you try the following things:

- Boot the box with the debug.mpsafenet=0 tunable set in loader.conf and
  see if the problem recurs?

- Update to 5-STABLE and try with and without debug.mpsafenet=0?  A number
  of TCP locking changes have been made there, and one may help.

Does it happen for every SSH session, or only some? 

Thanks,

Robert N M Watson


> 
> This problem is reproductible using the following steps:
> 
> Connect to the host and when asked for the password type Ctrl-C. On a 
> uniprocessor machine you will have a CLOSE-WAIT timeout that timeouts 
> :-) after one or two minutes. Not so on an SMP machine, the CLOSE-WAIT 
> state lasts forever.
> 
> The problem is if you have more than 10 sessions that fail in the same 
> situation your host ssh daemon is no more usable and you must kill it.
> 
> Thanks,
> Cyril Elkaim
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