Messages in this thread | | | Date | Thu, 12 Nov 2015 09:54:18 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86/mm: fix regression with huge pages on PAE |
| |
* Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote:
> diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h > index c5b7fb2774d0..cc071c6f7d4d 100644 > --- a/arch/x86/include/asm/page_types.h > +++ b/arch/x86/include/asm/page_types.h > @@ -9,19 +9,21 @@ > #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT) > #define PAGE_MASK (~(PAGE_SIZE-1)) > > +#define PMD_PAGE_SIZE (_AC(1, UL) << PMD_SHIFT) > +#define PMD_PAGE_MASK (~(PMD_PAGE_SIZE-1)) > + > +#define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT) > +#define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1)) > + > #define __PHYSICAL_MASK ((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1)) > #define __VIRTUAL_MASK ((1UL << __VIRTUAL_MASK_SHIFT) - 1) > > -/* Cast PAGE_MASK to a signed type so that it is sign-extended if > +/* Cast *PAGE_MASK to a signed type so that it is sign-extended if > virtual addresses are 32-bits but physical addresses are larger > (ie, 32-bit PAE). */ > #define PHYSICAL_PAGE_MASK (((signed long)PAGE_MASK) & __PHYSICAL_MASK) > - > -#define PMD_PAGE_SIZE (_AC(1, UL) << PMD_SHIFT) > -#define PMD_PAGE_MASK (~(PMD_PAGE_SIZE-1)) > - > -#define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT) > -#define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1)) > +#define PHYSICAL_PMD_PAGE_MASK (((signed long)PMD_PAGE_MASK) & __PHYSICAL_MASK) > +#define PHYSICAL_PUD_PAGE_MASK (((signed long)PUD_PAGE_MASK) & __PHYSICAL_MASK)
that's a really odd way of writing it, 'long' is signed by default ...
There seems to be 150+ such cases in the kernel source though - weird.
More importantly, how does this improve things on 32-bit PAE kernels? If I follow the values correctly then PMD_PAGE_MASK is 'UL' i.e. 32-bit:
> +#define PMD_PAGE_SIZE (_AC(1, UL) << PMD_SHIFT) > +#define PMD_PAGE_MASK (~(PMD_PAGE_SIZE-1))
thus PHYSICAL_PMD_PAGE_MASK is 32-bit too:
> +#define PHYSICAL_PMD_PAGE_MASK (((signed long)PMD_PAGE_MASK) & __PHYSICAL_MASK)
so how is the bug fixed?
Thanks,
Ingo
| |