Re: [PATCH 1/4 V2] [tip:x86/mm] Correcting improper large page preservation

From: Siarhei Liakh
Date: Thu Jun 10 2010 - 22:11:44 EST

On Sun, Jun 6, 2010 at 9:00 PM, Siarhei Liakh <sliakh.lkml@xxxxxxxxx> wrote:
> This patch fixes a bug in try_preserve_large_page() which may result
> in improper large page preservation and improper application of page
> attributes to the memory area outside of the original change request.
> More specifically, the problem manifests itself when set_memory_*() is
> called for several pages at the beginning of the large page and
> try_preserve_large_page() erroneously concludes that the change can be
> applied to whole large page.
> The fix consists of 3 parts:
> 1. addition of "required" protection attributes in
> static_protections(), so .data and .bss can be guaranteed to stay "RW"
> 2. static_protections() is now called for every small page within
> large page to determine compatibility of new protection attributes
> (instead of just small pages within the requested range).
> 3. large page can be preserved only if attribute change is
> large-page-aligned and covers whole large page.
> V1:  try_preserve_large_page() patch for Linux 2.6.34-rc2
> V2:  replaced pfn check with address check for kernel rw-data
> Signed-off-by: Siarhei Liakh <sliakh.lkml@xxxxxxxxx>
> Signed-off-by: Xuxian Jiang <jiang@xxxxxxxxxxx>
> Reviewed-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
> ---

Does anyone have any feedback on this patch set?

Thank you.
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