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From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Cc: "Sven Köhler" <skoehler@upb.de>
Subject: Re: [uml-devel] errors in uml-guest log
Date: Thu, 10 Nov 2005 12:38:46 +0100	[thread overview]
Message-ID: <200511101238.47223.blaisorblade@yahoo.it> (raw)
In-Reply-To: <dkuq7o$u24$1@sea.gmane.org>

On Thursday 10 November 2005 07:43, Sven Köhler wrote:
> Hi,
>
> an UML-guest-kernel 2.6.14 (without any additional patches) is running
> on a host with kernel 2.6.12.3-skas3-v8.2 host.
> Can anybody explain this error-message to me, 
Yes, I can.

In short: don't worry, I get it too at times and I must just remove this 
warning, it was introduced recently (by me) and it's wrong (as I later 
discovered).

> which occur periodically
> in the guests log:

More that "periodically" it's randomically. On a kernel compile loop with -jN, 
I used to get that more or less once every hour, but with high variability. 
Just had no time to proof-check and send all patches I have in my queue.

> Badness in handle_page_fault at arch/um/kernel/trap_kern.c:98

> 0f3d3b30:  [<08062f04>] handle_page_fault+0x1c4/0x260
> 0f3d3b70:  [<08063047>] segv+0xa7/0x2e0
> 0f3d3b90:  [<080ba701>] sys_read+0x51/0x80
> 0f3d3bd0:  [<08053680>] init_udf_fs+0x30/0x50
> 0f3d3c00:  [<08053680>] init_udf_fs+0x30/0x50
> 0f3d3c20:  [<08053680>] init_udf_fs+0x30/0x50
> 0f3d3c40:  [<08065291>] get_skas_faultinfo+0x51/0xc0
> 0f3d3c60:  [<08065358>] handle_segv+0x58/0x60
> 0f3d3c80:  [<08065a1d>] userspace+0x1ed/0x220
> 0f3d3cd0:  [<08066d94>] force_flush_all_skas+0x44/0x50
> 0f3d3cf0:  [<08066621>] fork_handler+0xc1/0xe0

It's an error message I introduced to detect a possible bug; however, I later 
discovered that under high load this warning can be triggered without a real 
problem.

The problem would be a "100% CPU usage" loop (a process endlessly causing 
guest page faults) right after the warning, so if you haven't got the problem 
the warning is a false positive.

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	

	
		
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      reply	other threads:[~2005-11-10 11:31 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-11-10  6:43 [uml-devel] errors in uml-guest log Sven Köhler
2005-11-10 11:38 ` Blaisorblade [this message]

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