Commit fd28f5d4 authored by Christoffer Dall's avatar Christoffer Dall Committed by Catalin Marinas

arm64: Don't report clear pmds and puds as huge

The current pmd_huge() and pud_huge() functions simply check if the table
bit is not set and reports the entries as huge in that case.  This is
counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
it is inconsistent with at least arm and x86.

To prevent others from making the same mistake as me in looking at code
that calls these functions and to fix an issue with KVM on arm64 that
causes memory corruption due to incorrect page reference counting
resulting from this mistake, let's change the behavior.
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: default avatarSteve Capper <steve.capper@linaro.org>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Fixes: 084bd298 ("ARM64: mm: HugeTLB support.")
Cc: <stable@vger.kernel.org> # 3.11+
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent b265da5a
...@@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) ...@@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
int pmd_huge(pmd_t pmd) int pmd_huge(pmd_t pmd)
{ {
return !(pmd_val(pmd) & PMD_TABLE_BIT); return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
} }
int pud_huge(pud_t pud) int pud_huge(pud_t pud)
{ {
#ifndef __PAGETABLE_PMD_FOLDED #ifndef __PAGETABLE_PMD_FOLDED
return !(pud_val(pud) & PUD_TABLE_BIT); return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
#else #else
return 0; return 0;
#endif #endif
......
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