Re: [PATCH 0/2] pageattr fixes for pmd/pte_present

[Simon Jeons <simon.jeons@gmail.com>]

What's the status of these two patches?

On Mon, 2012-12-17 at 19:00 +0100, Andrea Arcangeli wrote:
> Hi,
> 
> I got a report for a minor regression introduced by commit
> 027ef6c87853b0a9df53175063028edb4950d476.
> 
> So the problem is, pageattr creates kernel pagetables (pte and pmds)
> that breaks pte_present/pmd_present and the patch above exposed this
> invariant breakage for pmd_present.
> 
> The same problem already existed for the pte and pte_present and it
> was fixed by commit 660a293ea9be709b893d371fbc0328fcca33c33a (if it
> wasn't for that commit, it wouldn't even be a regression). That fix
> avoids the pagefault to use pte_present. I could follow through by
> stopping using pmd_present/pmd_huge too.
> 
> However I think it's more robust to fix pageattr and to clear the
> PSE/GLOBAL bitflags too in addition to the present bitflag. So the
> kernel page fault can keep using the regular
> pte_present/pmd_present/pmd_huge.
> 
> The confusion arises because _PAGE_GLOBAL and _PAGE_PROTNONE are
> sharing the same bit, and in the pmd case we pretend _PAGE_PSE to be
> set only in present pmds (to facilitate split_huge_page final tlb
> flush).
> 
> Andrea Arcangeli (2):
>   Revert "x86, mm: Make spurious_fault check explicitly check the
>     PRESENT bit"
>   pageattr: prevent PSE and GLOABL leftovers to confuse pmd/pte_present
>     and pmd_huge
> 
>  arch/x86/mm/fault.c    |    8 +------
>  arch/x86/mm/pageattr.c |   50 +++++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 48 insertions(+), 10 deletions(-)
> 
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