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

    * Siarhei Liakh <sliakh.lkml@gmail.com> wrote:

    > On Tue, Apr 6, 2010 at 10:51 AM, Siarhei Liakh <sliakh.lkml@gmail.com> wrote:
    > > On Sat, Apr 3, 2010 at 2:43 AM, Suresh Siddha <suresh.b.siddha@intel.com> wrote:
    > >> On Wed, 2010-03-31 at 18:59 -0700, Siarhei Liakh wrote:
    > >>> + ? ? /*
    > >>> + ? ? ?* .data and .bss should always be writable.
    > >>> + ? ? ?*/
    > >>> + ? ? if ((within(pfn, __pa((unsigned long)_sdata) >> PAGE_SHIFT,
    > >>> + ? ? ? ? ? ? ? ?__pa((unsigned long)_edata) >> PAGE_SHIFT)) ||
    > >>> + ? ? ? ? (within(pfn, __pa((unsigned long)__bss_start) >> PAGE_SHIFT,
    > >>> + ? ? ? ? ? ? ? ?__pa((unsigned long)__bss_stop) >> PAGE_SHIFT))) {
    > >>> + ? ? ? ? ? ? pgprot_val(required) |= _PAGE_RW;
    > >>> + ? ? }
    > >>
    > >> I have reviewed this patch and the only comment I have is:
    > >>
    > >> On 64bit kernels, kernel text/data mapping and kernel identity mappings
    > >> are different virtual addresses mapping to same pfn ranges. For the
    > >> data/bss pages, does it help (in identifying certain data corruptions
    > >> more easily) in making the kernel identity mapping to be set to
    > >> read-only and enforce the need of RW only for the kernel data mappings.
    > >>
    > >> Or is there some obscure code that uses something like
    > >> __va(__pa(data_symbol)) and writes to it?
    > >>
    > >> If not, we can remove the __pa() constructs above and use the addr for
    > >> comparisons.
    > >
    > > Done.
    > > Patch V2 have been posted.
    >
    > Does anyone have any feedback on the whole kernel RO/NX patch set? Or should
    > I re-post all 4 patches one more time?
    >
    > Thank you.

    Please do - i havent seen any other review feedback.

    Thanks,

    Ingo


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