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Date: Tue, 11 Nov 2008 15:19:42 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Mikael Pettersson <mikpe@it.uu.se>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>,
       Alexey Dobriyan <adobriyan@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Ken Chen <kenchen@google.com>, linux-kernel@vger.kernel.org,
       Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [patch] add /proc/pid/stack to dump task's stack trace
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* Mikael Pettersson <mikpe@it.uu.se> wrote:

> Ingo Molnar writes:
>  > > >  # cat /proc/18579/stack
>  > > >  [<ffffffffffffffff>] 0xffffffffffffffff
>  > > 
>  > > so this file provides view of _kernel_ stack only?
>  > > shouldn't it be named kernel-stack then?
>  > 
>  > it prints the kernel stack right now, but i'd not restrict it to 
>  > the kernel stack conceptually: i think we could eventually expand 
>  > it to print the user-space portion of the stack as well. (in the 
>  > case when user-space is built with frame pointers) We've got code 
>  > for that in the kernel already. It would be an easy one-stop-shop 
>  > for full-range.
> 
> That would be quite fragile given the fact that user-space only has 
> to follow standard ABIs at specific points like calls to standard 
> library functions. In between, anything can, and does, happen.

it's not fragile to robustly walk the userspace stack. The result 
might not always be meaningful of course.

	Ingo
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