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Re: [PATCH] x86/mm: fix regression with huge pages on PAE

From Toshi Kani <toshi.kani@hpe.com>
Newsgroups linux.kernel
Subject Re: [PATCH] x86/mm: fix regression with huge pages on PAE
Date 2015-11-10 00:50 +0100
Message-ID <qt4md-5Cw-7@gated-at.bofh.it> (permalink)
References <qt3Tc-5oe-19@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue, 2015-11-10 at 01:18 +0200, Kirill A. Shutemov wrote:
> Recent PAT patchset has caused issue on 32-bit PAE machines:
 :
> The problem is in pmd_pfn_mask() and pmd_flags_mask(). These helpers use
> PMD_PAGE_MASK to calculate resulting mask. PMD_PAGE_MASK is 'unsigned
> long', not 'unsigned long long' as physaddr_t. As result upper bits of
> resulting mask is truncated.
> 
> The patch reworks code to use PMD_SHIFT as base of mask calculation
> instead of PMD_PAGE_MASK.
> 
> pud_pfn_mask() and pud_flags_mask() aren't problematic since we don't
> have PUD page table level on 32-bit systems, but they reworked too to be
> consistent with PMD counterpart.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-and-Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Fixes: f70abb0fc3da ("x86/asm: Fix pud/pmd interfaces to handle large PAT
> bit")
> Cc: Toshi Kani <toshi.kani@hpe.com>
> ---
>  arch/x86/include/asm/pgtable_types.h | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pgtable_types.h
> b/arch/x86/include/asm/pgtable_types.h
> index dd5b0aa9dd2f..c1e797266ce9 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -279,17 +279,14 @@ static inline pmdval_t native_pmd_val(pmd_t pmd)
>  static inline pudval_t pud_pfn_mask(pud_t pud)
>  {
>  	if (native_pud_val(pud) & _PAGE_PSE)
> -		return PUD_PAGE_MASK & PHYSICAL_PAGE_MASK;
> +		return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;

Thanks for the fix!  Should we fix the PMD/PUD MASK/SIZE macros, so that we do
not hit the same issue again when they are used? 

--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -17,10 +17,10 @@
    (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_SIZE          (_AC(1, ULL) << PMD_SHIFT)
 #define PMD_PAGE_MASK          (~(PMD_PAGE_SIZE-1))

-#define PUD_PAGE_SIZE          (_AC(1, UL) << PUD_SHIFT)
+#define PUD_PAGE_SIZE          (_AC(1, ULL) << PUD_SHIFT)
 #define PUD_PAGE_MASK          (~(PUD_PAGE_SIZE-1))

Thanks,
-Toshi
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Thread

[PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-11-10 00:20 +0100
  Re: [PATCH] x86/mm: fix regression with huge pages on PAE Toshi Kani <toshi.kani@hpe.com> - 2015-11-10 00:50 +0100
    Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-11-10 01:00 +0100
      Re: [PATCH] x86/mm: fix regression with huge pages on PAE Toshi Kani <toshi.kani@hpe.com> - 2015-11-10 01:20 +0100
  Re: [PATCH] x86/mm: fix regression with huge pages on PAE Borislav Petkov <bp@alien8.de> - 2015-11-10 13:50 +0100
    Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-11-10 15:00 +0100
      Re: [PATCH] x86/mm: fix regression with huge pages on PAE Borislav Petkov <bp@alien8.de> - 2015-11-10 15:50 +0100
        Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-11-10 16:10 +0100
          Re: [PATCH] x86/mm: fix regression with huge pages on PAE Borislav Petkov <bp@alien8.de> - 2015-11-10 18:10 +0100
            Re: [PATCH] x86/mm: fix regression with huge pages on PAE Borislav Petkov <bp@alien8.de> - 2015-11-11 11:00 +0100
              Re: [PATCH] x86/mm: fix regression with huge pages on PAE Ingo Molnar <mingo@kernel.org> - 2015-11-12 08:50 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-11-12 09:00 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Ingo Molnar <mingo@kernel.org> - 2015-11-12 09:10 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-11-12 09:50 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Ingo Molnar <mingo@kernel.org> - 2015-11-12 10:00 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-11-12 10:10 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Ingo Molnar <mingo@kernel.org> - 2015-11-12 14:40 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Ingo Molnar <mingo@kernel.org> - 2015-11-12 10:00 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Linus Torvalds <torvalds@linux-foundation.org> - 2015-11-12 20:30 +0100
                Re: [PATCH] x86/mm: fix regression with huge pages on PAE Dan Williams <dan.j.williams@gmail.com> - 2015-11-13 10:10 +0100

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