From mboxrd@z Thu Jan  1 00:00:00 1970
From: imre.deak@nokia.com (Imre Deak)
Date: Mon, 28 Sep 2009 14:33:27 +0300
Subject: [PATCH] ARM: add warning for invalid kernel page faults
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To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Sep 28, 2009 at 01:26:24PM +0200, ext Russell King - ARM Linux wrote:
> On Mon, Sep 28, 2009 at 02:01:58PM +0300, Imre Deak wrote:
> > On Mon, Sep 28, 2009 at 12:27:10PM +0200, ext Russell King - ARM Linux wrote:
> > > [...]
> > >
> > > Now you're talking about different code - the bit I quoted was what was
> > > in your submitted patch, without deletion of intervening lines.  There
> > > was no else clause in your patch.
> > > 
> > > Please, go back and look at your original patch.
> > 
> > Ah, sorry. Missed that line when rebasing. I'll send an updated one.
> 
> Now I see what you're getting at.  Yes, we can make this a debugging
> option, but I believe it should exhibit the right behaviour.
> 
> In other words (and as I already covered) it should invoke the standard
> no_context thing if there isn't a fixup handler in place rather than
> continuing blindly on to try to handle the fault.  So, it should be:
> 
> 	if (!down_read_trylock(&mm->mmap_sem)) {
> 		if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
> 			goto no_context;
> 		down_read(&mm->mmap_sem);
> 	} else {
> +#ifdef CONFIG_DEBUG_VM
> +		if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
> +			goto no_context;
> +#endif

Ok, agreed. Do you need an updated patch?

--Imre