linux-kernel - Re: [patch 0/2] Protect crashkernel against BSS overlap

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Message-ID: <20071016162806.GB16521@suse.de>
Date:	Tue, 16 Oct 2007 18:28:06 +0200
From:	Bernhard Walle <bwalle@...e.de>
To:	Vivek Goyal <vgoyal@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	akpm@...ux-foundation.org, ak@...e.de
Subject: Re: [patch 0/2] Protect crashkernel against BSS overlap

* Vivek Goyal <vgoyal@...ibm.com> [2007-10-16 07:49]:
> 
> Shouldn't bootmem allocator have the functionality to flag an error if
> we try to reserve a memory which is already reserved? I see that bootmem
> allocator is currently printing a warning under CONFIG_DEBUG_BOOTMEM.

That's probably better, yes. See the next version.

> Wouldn't it be better if we reserve the code, data and bss memory also
> using bootmem allocator and when somebody tries to reserve craskernel memory
> and if there is an overlap, boot memory allocator should scream?

It's already marked as reserved. At least on i386 in my test.

> In second patch, you are checking for crash kernel reserved memory being
> beyond _end. That will make sure that there is no overlap with kernel
> text, data or bss. I am wondering then why do we need first patch and
> why should we register bss memory in the resources list. Second patch 
> would make sure that there is no overlap with crash kernel memory and kexec
> will not place any segment outside crashkernel memory.

I think we should also present the BSS to the user like we present
text and data.


Thanks,
   Bernhard
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