From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41bL603hfpzDrTJ for ; Thu, 26 Jul 2018 02:19:36 +1000 (AEST) Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6PGE4ZB025230 for ; Wed, 25 Jul 2018 12:19:33 -0400 Received: from e17.ny.us.ibm.com (e17.ny.us.ibm.com [129.33.205.207]) by mx0b-001b2d01.pphosted.com with ESMTP id 2ket5yr0ej-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 25 Jul 2018 12:19:33 -0400 Received: from localhost by e17.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 25 Jul 2018 12:19:32 -0400 From: "Aneesh Kumar K.V" To: npiggin@gmail.com, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, Naoya Horiguchi Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, "Aneesh Kumar K.V" Subject: [PATCH V2 5/6] powerpc/mm/thp: update pmd_trans_huge to check for pmd_present Date: Wed, 25 Jul 2018 21:49:02 +0530 In-Reply-To: <20180725161903.31257-1-aneesh.kumar@linux.ibm.com> References: <20180725161903.31257-1-aneesh.kumar@linux.ibm.com> Message-Id: <20180725161903.31257-5-aneesh.kumar@linux.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- .../include/asm/book3s/64/pgtable-64k.h | 3 +++ arch/powerpc/include/asm/book3s/64/pgtable.h | 18 ++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable-64k.h b/arch/powerpc/include/asm/book3s/64/pgtable-64k.h index d7ee249d6890..e3d4dd4ae2fa 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 fce9ce8781a0..8b80c5e16896 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -1129,6 +1129,10 @@ 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)); @@ -1163,8 +1167,22 @@ 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); -- 2.17.1