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