(forw) Re: Process stuck in STOP state

[Alfred Perlstein-2]

Can someone look at this?  This is pretty weird, it seems
that somehow there's some deadlock with vnode locks, but it
doesn't appear to be due a leaked vnode lock as "show lockednods"
doesn't show any vnodes locks.

The trace should be somewhat easy to figure out but I'm kinda
of stuck..

Any ideas how this could happen?

-Alfred

----- Forwarded message from Lin Jui-Nan Eric <ericlin@...> -----

From: "Lin Jui-Nan Eric" <ericlin@...>
To: "Alfred Perlstein" <alfred@...>
Cc: stable@...
Subject: Re: Process stuck in STOP state
Date: Fri, 26 Dec 2008 12:41:12 +0800
Message-ID: <47713ee10812252041p3b4ba9e8sa92772264bd2ac3b@...>

Hi,

Full back-trace is located here:
http://aqua.pixnet.tw/~jnlin/textdump/event3/1226/

On Fri, Dec 26, 2008 at 11:34 AM, Lin Jui-Nan Eric <ericlin@...> wrote:

> Hi,
>
> No, NFS is not working (df hangs, and cd /nfs/vol hangs, too). we have
> run fstat and see some NFS file is opened.
> I will do a full back-trace while this happened again. (It happens
> very frequently....about 10 times/day now)
>
> On Fri, Dec 26, 2008 at 11:26 AM, Alfred Perlstein <alfred@...> wrote:
>> * Lin Jui-Nan Eric <ericlin@...> [081225 02:44] wrote:
>>> Hi,
>>>
>>> We have done a textdump, located here: http://aqua.pixnet.tw/~jnlin/textdump/
>>> Thank you!
>>
>> Is NFS working when this happens?
>>
>> Can you run lsof too?
>>
>> It would be really good to get a backtrace from all processes, there's
>>  a ddb command to do this.
>>
>> -Alfred
>>
>>>
>>> On Wed, Dec 24, 2008 at 11:07 AM, Alfred Perlstein <alfred@...> wrote:
>>> > * Lin Jui-Nan Eric <ericlin@...> [081223 09:17] wrote:
>>> >> > Dear listers,
>>> >> >
>>> >> > Our FreeBSD Server uses NFS to access PHP files on NetApp, then serve
>>> >> > them with apache 2.2 (worker MPM + php fastcgi mode).
>>> >> Sorry. we use -STABLE now.
>>> >>
>>> >> event# uname -a
>>> >> FreeBSD event 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #1: Thu Dec  4
>>> >> 01:45:42 CST 2008     root@event:/usr/obj/usr/src/sys/KERNEL  amd64
>>> >> _______________________________________________
>>> >> freebsd-stable@... mailing list
>>> >> http://lists.freebsd.org/mailman/listinfo/freebsd-stable
>>> >> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@..."
>>> >
>>> > It'd be good if you could get to ddb and do a "show all"
>>> > or "threads" and get all threads backtrace to see what's happening.
>>> >
>>> > thank you,
>>> > --
>>> > - Alfred Perlstein
>>> >
>>> _______________________________________________
>>> freebsd-stable@... mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-stable
>>> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@..."
>>
>> --
>> - Alfred Perlstein
>>
>

----- End forwarded message -----

--
- Alfred Perlstein
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[Tor Egge]

> Can someone look at this?  This is pretty weird, it seems
> that somehow there's some deadlock with vnode locks, but it
> doesn't appear to be due a leaked vnode lock as "show lockednods"
> doesn't show any vnodes locks.
>
> The trace should be somewhat easy to figure out but I'm kinda
> of stuck..
>
> Any ideas how this could happen?

I had a brief look at <URL:http://aqua.pixnet.tw/~jnlin/textdump/event3/1230/>

msgbuf.txt contained info about some nfs vnodes locked by pid 27645.

It looks like thread suspension is broken for the SINGLE_NO_EXIT case.

Threads performing an interruptable sleep are suspended, even while holding
other resources (e.g. vnode locks).

Threads performing a non-interruptable sleep, waiting for resources held by the
suspended threads are not suspended.

The thread that started the suspension is not woken up since some of the
other threads are not yet suspended.

- Tor Egge
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