linux-kernel - Re: Callchain contains impossible call

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Message-Id: <E1Hu4S6-0001LJ-00@dorka.pomaz.szeredi.hu>
Date:	Fri, 01 Jun 2007 12:33:50 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	george.krajcsovits@...il.com
CC:	linux-kernel@...r.kernel.org
Subject: Re: Callchain contains impossible call

Hi Krajo,

> this is probably RTFM (where is this manual?), but how did I get a
> callchain on a uniprocessor
> system where there are two functions that cannot be a part of it,
> because they don't call anything ? (kfree_skbmem and __kmalloc). Also
> at the end one function call is there twice.
> 
> Seems like stack corruption, but I did try to close others out with
> spin_lock_bh. This part of the code is called from kernel traps and
> softirq for ethernet RX.

I'm not an expert, but I think you basically have two options:

 - Turn on CONFIG_FRAME_POINTER

 - Gnaw through the stack trace (from bottom to top), matching up the
   entry points with actual function calls in the assembly.  That way
   you'll see which of the entries are bogus, and which correspond to
   a real call somewhere in the trace.

Miklos
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