linux-kernel - Re: PATCH [1/1]: Don't return symbol lables in init sections after they have been freed

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Message-Id: <200803051253.28761.rgetz@blackfin.uclinux.org>
Date:	Wed, 5 Mar 2008 12:53:27 -0500
From:	Robin Getz <rgetz@...ckfin.uclinux.org>
To:	"Rusty Russell" <rusty@...tcorp.com.au>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"LKML" <linux-kernel@...r.kernel.org>
Subject: Re: PATCH [1/1]: Don't return symbol lables in init sections after they have been freed

On Tue 4 Mar 2008 20:43, Rusty Russell pondered:
> On Wednesday 05 March 2008 10:47:15 Robin Getz wrote:
> > From: Robin Getz <rgetz@...ckfin.uclinux.org>
> >
> > Today, when module names are looked up, we do not qualify them (check to
> > see if the init section is still active or not). This can lead to problems
> > when kernel modules get loaded into the same address that the kernel init
> > section (or other module's init section was at). We sometimes return the
> > old / no lomnger there
> >
> > This leads to bogus OOPS messages, and developers wasting their time
> > looking for problems (in the kernel init section) where there are none
> > (since it was a module).
> 
> Hi Robin,
> 
>     This is a great explanation, with only one problem: it isn't true.  

I can replicate this on 2.6.24.3 (at least on noMMU) in the kernel init 
section. 

> mod->init_size is set to zero after init.

So, I have seen the problem on the init section, and suspected it could happen 
on module init, but it looks like I missed that portion of the code - sorry.

>     As to the actual patch, your kallsyms.c patch matches 
> a2da4052f1df6bc77749f84496fe731ab8b458f7's change to extable.c: please 
> resubmit with just that one. 

Will do.

> For bonus points, look at combining the 
> extable and kallsyms logic so we don't diverge in future...

Let me see what I can do. 
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