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Date:      Wed, 29 Feb 2012 14:20:37 -0500
From:      Arnaud Lacombe <lacombar@gmail.com>
To:        Attilio Rao <attilio@freebsd.org>
Cc:        freebsd-stable <freebsd-stable@freebsd.org>
Subject:   Re: Complete hang on 9.0-RELEASE
Message-ID:  <CACqU3MWdJAp2XqWESUTtvX7CeESm=WEcqcRa0T105Kx95jMXzA@mail.gmail.com>
In-Reply-To: <CAJ-FndCtA6F=XzTbYsDD1y3-aXuOSMDobtSuOgdNVwaNU4kY_A@mail.gmail.com>
References:  <CACqU3MUefo4mG3GdZnj6kxxFx4H_M3-NLys8pCKptqNU4r_ywA@mail.gmail.com> <CACqU3MVs1mpiQpjE9xC8aFAKxhzbjUgC_6GKWdAkyr8OGJhycw@mail.gmail.com> <CAJ-FndDz6eRamnf7v6kZwwZQp-JaLYUKX6Gx7MYuZGEFNagmfQ@mail.gmail.com> <CACqU3MV-mDHzmnXY3Mzc%2BBnimJSnUTAPk66fh%2Bzzdfgz4OyPFg@mail.gmail.com> <CACqU3MVL14TxJ81rbM-Oq2P8GZCE0hPKzQpb5eJqZ32YdowSjQ@mail.gmail.com> <CACqU3MVko6jKjs98JeS1NqBp%2BFR0YtMqPq570J3dN7BPyFvdkA@mail.gmail.com> <CAJ-FndCtA6F=XzTbYsDD1y3-aXuOSMDobtSuOgdNVwaNU4kY_A@mail.gmail.com>

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Hi,

On Wed, Feb 29, 2012 at 1:44 PM, Attilio Rao <attilio@freebsd.org> wrote:
> 2012/2/29, Arnaud Lacombe <lacombar@gmail.com>:
>> Hi,
>>
>> On Wed, Feb 29, 2012 at 12:59 PM, Arnaud Lacombe <lacombar@gmail.com> wr=
ote:
>>> Hi,
>>>
>>> On Mon, Feb 27, 2012 at 12:48 PM, Arnaud Lacombe <lacombar@gmail.com>
>>> wrote:
>>>> Hi,
>>>>
>>>> On Mon, Feb 27, 2012 at 10:36 AM, Attilio Rao <attilio@freebsd.org>
>>>> wrote:
>>>>> 2012/2/27, Arnaud Lacombe <lacombar@gmail.com>:
>>>>>> Hi,
>>>>>>
>>>>>> On Tue, Feb 14, 2012 at 11:41 AM, Arnaud Lacombe <lacombar@gmail.com=
>
>>>>>> wrote:
>>>>>>> Hi folks,
>>>>>>>
>>>>>>> For the records, I was running some tests yesterday on top of a
>>>>>>> 9.0-RELEASE, amd64, kernel when the box hanged. At the time of the
>>>>>>> hang, the box was running a process with about 2800 threads with he=
avy
>>>>>>> IPC between 1400 writers and 1400 readers. The box was in single us=
er
>>>>>>> mode (/bin/sh coming from FreeBSD 7.4-STABLE). Here is the beginnin=
g
>>>>>>> of the dmesg:
>>>>>>>
>>>>>> This happened a second time, now with FreeBSD 8.2-RELEASE. Complete
>>>>>> machine hang. The machine was running about 4000 threads in a single
>>>>>> process, all the other condition are the same.
>>>>>
>>>>> Arnaud,
>>>>> can you please break in your kernel via KDB, collect the following
>>>>> informations from the DDB prompt:
>>>>> - ps
>>>>> - alltrace
>>>>> - show allpcpu
>>>>> - possibly get a coredump with 'call doadump'
>>>>>
>>>> Will do, but I'll need to rebuild a kernel to include DDB.
>>>>
>>>>> and in the end provide all those along with kernel binary and possibl=
y
>>>>> sources somewhere?
>>>>>
>>>> I'll be testing a bare `release/8.2.0' with the following patch:
>>>>
>>>> diff --git a/sys/amd64/conf/GENERIC b/sys/amd64/conf/GENERIC
>>>> index c3e0095..7bd997f 100644
>>>> --- a/sys/amd64/conf/GENERIC
>>>> +++ b/sys/amd64/conf/GENERIC
>>>> @@ -79,6 +79,10 @@ options =A0 =A0 =A0INCLUDE_CONFIG_FILE =A0 =A0 # In=
clude this
>>>> file in kernel
>>>>
>>>> =A0options =A0 =A0 =A0 =A0KDB =A0 =A0 =A0 =A0 =A0 # Kernel debugger re=
lated code
>>>> =A0options =A0 =A0 =A0 =A0KDB_TRACE =A0 =A0 # Print a stack trace for =
a panic
>>>> +options =A0 =A0 =A0 =A0DDB
>>>> +options =A0 =A0 =A0 =A0BREAK_TO_DEBUGGER
>>>> +options =A0 =A0 =A0 =A0ALT_BREAK_TO_DEBUGGER
>>>>
>>>> =A0# Make an SMP-capable kernel by default
>>>> =A0options =A0 =A0 =A0 =A0SMP =A0 =A0 =A0 =A0 =A0 # Symmetric MultiPro=
cessor Kernel
>>>>
>>> ok, it happened again after 2 days, the process was running about 3200
>>> threads. I'm trying to break into DDB and let you know, I'm not that
>>> successful for now...
>>>
>> No luck. None of BREAK or ALT_BREAK are responding. I will not touch
>> the system in the next few hours if you want me to test something on
>> it. In the event of 8.2-RELEASE or 9.0-RELEASE are =A0not meant to work
>> reliably on top of a 7.4-RELEASE userland, I will re-setup the test to
>> occurs on a clean 9.0-RELEASE system and re-try.
>
> We allow to break KBI when new releases happens, thus this may cause a
> breakage for you, even if a deadlock is really not something you want.
>
> Can you try enabling SW_WATCHDOG, DEADLKRES and possibly arm your ichwd?
> if the breakage involves clocks or interrupt sources there are still
> chances they will be able to catch it though.
>
> However, it doesn't seem you are setup with a proper serial console?
The serial console is working definitively fine. I can break into DDB
at will when the test is running. I did not test with ALT_BREAK
per-se, but BREAK does work.

 - Arnaud

> If this is the case, you need to go with a textdump in order to
> collect DDB output.
> Or if you have it you might try with sending a serial break and kernel
> should break in DDB.
>
> Thanks,
> Attilio
>
>
> --
> Peace can only be achieved by understanding - A. Einstein



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