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Subject: Re: [im]proper use of stack?
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: mfbaustx <mfbaustx@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Date: Thu, 19 Oct 2006 23:22:43 +0100
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Ar Iau, 2006-10-19 am 11:23 -0500, ysgrifennodd mfbaustx:
> So... I know that there is some small-ish amount of kernel stack space  
> available per-process, and the kernel uses this area when executing on a  
> process's behalf (system call, etc).  Let's say I allocate (via an  
> automatic/stack-based storage) some smallish structure which I want a  
> kernel thread to populate (or interrupt context... some context other than  
> my process's context).
> 
> If my process gets context swapped, is my kernel-based stack pointer  
> always valid?

Have a look how the kernel sleep/wakeup system work. We rely on the
property that the kernel stacks of tasks don't move nor do they get
swapped out.