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Subject: Re: [RFC PATCH v2 3/4] powerpc: Don't bolt the hpte in
 kernel_map_linear_page()
From: Li Zhong <zhong@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 16 Apr 2013 10:51:50 +0800
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On Mon, 2013-04-15 at 13:27 +0200, Benjamin Herrenschmidt wrote:
> On Mon, 2013-04-15 at 16:15 +0800, Li Zhong wrote:
> 
> > So the code is implemented in ppc_md.hpte_remove(), may be called by
> > __hash_huge_page(), and asm code htab_call_hpte_remove?
> > 
> > > This is why the linear mapping (and the vmemmap) must be bolted.
> > 
> > If not, it would result the infinite recursion like above?
> 
> Potentially, we don't expect to fault linear mapping or vmemmap entries
> on demand. We aren't equipped to do it and we occasionally have code
> path that access the linear mapping and cannot afford to have SRR0 and
> SRR1 clobbered by a page fault.

Thank you for the education :)

Thanks, Zhong

> 
> Cheers,
> Ben.
> 
>