linux-kernel - Re: Strange system hangs

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Date:	Sun, 2 Dec 2007 16:09:30 +0100 (CET)
From:	Krzysztof Oledzki <olel@....pl>
To:	Nick Piggin <nickpiggin@...oo.com.au>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	osterried@...se.de, Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: Strange system hangs



On Sat, 29 Sep 2007, Nick Piggin wrote:

> On Friday 28 September 2007 18:42, Krzysztof Oledzki wrote:
>> Hello,
>>
>> I am experiencing weird system hangs. Once about 2-5 weeks system freezes
>> and stops accepting remote connections, so it is no longer possible to
>> connect to most important services: smtp (postfix), www (squid) or even
>> ssh. Such connection is accepted but then it hangs.
>>
>> What is strange, that previously established ssh session is usable. It is
>> possible to work on such system until you do something stupid like "less
>> /var/log/all.log". Using strace I found that process blocks on:
>
> Is this a regression? If so, what's the most recent kernel that didn't show
> the problem?
>
> The symptoms could be consistent with some place doing a
> balance_dirty_pages while holding a lock that is required for IO, but I can't
> see a smoking gun (you've got contention on i_mutex, but that should be
> OK).
>
> Can you see if there is any memory under writeback that isn't being
> completed (sysrq+M), also a list the locks held after the hang might be
> helpful (compile in lockdep and sysrq+D)
>
> Is anything currently running? (sysrq+P and even a full sysrq+T task list
> could be useful).
>
> Are any IO errors occurring at all?

It seems that 2.6.23.x still fails but somehow different. I updated my 
bugreport at: http://bugzilla.kernel.org/show_bug.cgi?id=9182. There are 
new attachments with traces and an oops that happened while I was taking 
the debugging data.

Thank you.

Best regards,


 			Krzysztof Olędzki