arm64: Don't report clear pmds and puds as huge
authorChristoffer Dall <christoffer.dall@linaro.org>
Wed, 1 Jul 2015 12:08:31 +0000 (14:08 +0200)
committerCatalin Marinas <catalin.marinas@arm.com>
Wed, 1 Jul 2015 13:29:28 +0000 (14:29 +0100)
commitfd28f5d439fca77348c129d5b73043a56f8a0296
tree8acfb71906a63563b5a1e6d1abe86c707184f3d7
parentb265da5a45ce60bd3d7505cc0eaa6cfba50946a1
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: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Steve Capper <steve.capper@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.")
Cc: <stable@vger.kernel.org> # 3.11+
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch/arm64/mm/hugetlbpage.c