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Re: looking for help interpreting softlockup/stack trace

To: Ralf Baechle <>
Subject: Re: looking for help interpreting softlockup/stack trace
From: David Daney <>
Date: Wed, 06 Aug 2008 11:57:32 -0700
Cc: Chris Friesen <>,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <>
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Ralf Baechle wrote:
On Tue, Aug 05, 2008 at 12:25:02PM -0600, Chris Friesen wrote:

I've run into an interesting issue with an Octeon-based board, where it just seems to hang. I suspect we're hitting some kind of locking bug, and I'm trying to track it down. If it matters, the kernel is quite old (heavily patched 2.6.14) and I've got no chance of upgrading it. (The usual embedded scenario.)

I've added some scheduler instrumentation, as well as adding a stack dump to the output of the softlockup code.

In the trace below, is "epc" the program counter at the time of the timer interrupt? How does "ra" fit into this, given that the function whose address it contains isn't seen in the stack trace until quite a ways down?

$LBB378 is an internal symbol.  The value of RA may not be very informative
if it was overwritten by a random subroutine call.

I have thought about eliminating these internal labels when the module's 
symbols are read.  Would this make any sense?

David Daney

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