From: Aneesh Kumar K.V Date: Thu, 20 Sep 2018 18:09:46 +0000 (+0530) Subject: powerpc/mm/thp: update pmd_trans_huge to check for pmd_present X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8890e03380d361f67fdd7f91758d93339fd66ca9;p=linux.git powerpc/mm/thp: update pmd_trans_huge to check for pmd_present We need to make sure pmd_trans_huge returns false for a pmd migration entry. We mark the migration entry by clearing the _PAGE_PRESENT bit. We keep the _PAGE_PTE bit set to indicate a leaf page table entry. Hence we need to make sure we check for pmd_present() so that pmd_trans_huge won't return true on pmd migration entry. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/include/asm/book3s/64/pgtable-64k.h b/arch/powerpc/include/asm/book3s/64/pgtable-64k.h index d7ee249d6890c..e3d4dd4ae2fab 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable-64k.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable-64k.h @@ -10,6 +10,9 @@ * * Defined in such a way that we can optimize away code block at build time * if CONFIG_HUGETLB_PAGE=n. + * + * returns true for pmd migration entries, THP, devmap, hugetlb + * But compile time dependent on CONFIG_HUGETLB_PAGE */ static inline int pmd_huge(pmd_t pmd) { diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 8feb4a3240d52..e24db2aa260f9 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -1136,6 +1136,10 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set); } +/* + * returns true for pmd migration entries, THP, devmap, hugetlb + * But compile time dependent on THP config + */ static inline int pmd_large(pmd_t pmd) { return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE)); @@ -1170,8 +1174,22 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, unsigned long addr, pmd_hugepage_update(mm, addr, pmdp, 0, _PAGE_PRIVILEGED); } +/* + * Only returns true for a THP. False for pmd migration entry. + * We also need to return true when we come across a pte that + * in between a thp split. While splitting THP, we mark the pmd + * invalid (pmdp_invalidate()) before we set it with pte page + * address. A pmd_trans_huge() check against a pmd entry during that time + * should return true. + * We should not call this on a hugetlb entry. We should check for HugeTLB + * entry using vma->vm_flags + * The page table walk rule is explained in Documentation/vm/transhuge.rst + */ static inline int pmd_trans_huge(pmd_t pmd) { + if (!pmd_present(pmd)) + return false; + if (radix_enabled()) return radix__pmd_trans_huge(pmd); return hash__pmd_trans_huge(pmd);