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Subject: Re: [PATCH 03/10] mm: Convert p[te|md]_numa users to
 p[te|md]_protnone_numa
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Mel Gorman <mgorman@suse.de>
Date: Tue, 02 Dec 2014 09:44:09 +1100
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Cc: Rik van Riel <riel@redhat.com>,
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 Hugh Dickins <hughd@google.com>, Linux Kernel <linux-kernel@vger.kernel.org>,
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On Fri, 2014-11-21 at 13:57 +0000, Mel Gorman wrote:
> void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
>                 pte_t pte)
>  {
> -#ifdef CONFIG_DEBUG_VM
> -       WARN_ON(pte_val(*ptep) & _PAGE_PRESENT);
> -#endif
> +       /*
> +        * When handling numa faults, we already have the pte marked
> +        * _PAGE_PRESENT, but we can be sure that it is not in hpte.
> +        * Hence we can use set_pte_at for them.
> +        */
> +       VM_WARN_ON((pte_val(*ptep) & (_PAGE_PRESENT | _PAGE_USER)) ==
> +               (_PAGE_PRESENT | _PAGE_USER));
> +

His is that going to fare with set_pte_at() called for kernel pages ?

Cheers,
Ben.