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