Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 081/100] ARM: 8579/1: mm: Fix definition of pmd_mknotpresent | Date | Fri, 19 Aug 2016 09:11:20 +0200 |
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From: Steve Capper <steve.capper@arm.com>
3.12-stable review patch. If anyone has any objections, please let me know.
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commit 56530f5d2ddc9b9fade7ef8db9cb886e9dc689b5 upstream.
Currently pmd_mknotpresent will use a zero entry to respresent an invalidated pmd.
Unfortunately this definition clashes with pmd_none, thus it is possible for a race condition to occur if zap_pmd_range sees pmd_none whilst __split_huge_pmd_locked is running too with pmdp_invalidate just called.
This patch fixes the race condition by modifying pmd_mknotpresent to create non-zero faulting entries (as is done in other architectures), removing the ambiguity with pmd_none.
[catalin.marinas@arm.com: using L_PMD_SECT_VALID instead of PMD_TYPE_SECT]
Fixes: 8d9625070073 ("ARM: mm: Transparent huge page support for LPAE systems.") Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Russell King <linux@armlinux.org.uk> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- arch/arm/include/asm/pgtable-3level.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index 8afa39f81477..0f153b62d253 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -237,8 +237,11 @@ PMD_BIT_FUNC(mkyoung, |= PMD_SECT_AF); #define pfn_pmd(pfn,prot) (__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))) #define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot) -/* represent a notpresent pmd by zero, this is used by pmdp_invalidate */ -#define pmd_mknotpresent(pmd) (__pmd(0)) +/* represent a notpresent pmd by faulting entry, this is used by pmdp_invalidate */ +static inline pmd_t pmd_mknotpresent(pmd_t pmd) +{ + return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID); +} static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) { -- 2.9.3
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