From: Steve Capper Date: Tue, 7 Jun 2016 16:58:06 +0000 (+0100) Subject: ARM: 8579/1: mm: Fix definition of pmd_mknotpresent X-Git-Tag: firefly_0821_release~176^2~4^2~37^2~108 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=490a71c5feec87292126f5b5587d155f89fb2bd4;p=firefly-linux-kernel-4.4.55.git ARM: 8579/1: mm: Fix definition of pmd_mknotpresent 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 Acked-by: Will Deacon Cc: Russell King Signed-off-by: Steve Capper Signed-off-by: Catalin Marinas Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index e3dad00abcb3..fd929b5ded9e 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -258,10 +258,10 @@ 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 */ +/* represent a notpresent pmd by faulting entry, this is used by pmdp_invalidate */ static inline pmd_t pmd_mknotpresent(pmd_t pmd) { - return __pmd(0); + return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID); } static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)