From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9FF0C43603 for ; Wed, 18 Dec 2019 16:25:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E0CA227BF for ; Wed, 18 Dec 2019 16:25:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727813AbfLRQZC (ORCPT ); Wed, 18 Dec 2019 11:25:02 -0500 Received: from foss.arm.com ([217.140.110.172]:52244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726955AbfLRQZA (ORCPT ); Wed, 18 Dec 2019 11:25:00 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 16A2D113E; Wed, 18 Dec 2019 08:25:00 -0800 (PST) Received: from e112269-lin.arm.com (e112269-lin.cambridge.arm.com [10.1.196.56]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 88BCB3F719; Wed, 18 Dec 2019 08:24:57 -0800 (PST) From: Steven Price To: Andrew Morton , linux-mm@kvack.org Cc: Steven Price , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Dave Hansen , Ingo Molnar , James Morse , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Peter Zijlstra , Thomas Gleixner , Will Deacon , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mark Rutland , "Liang, Kan" Subject: [PATCH v17 12/23] mm: pagewalk: Allow walking without vma Date: Wed, 18 Dec 2019 16:23:51 +0000 Message-Id: <20191218162402.45610-13-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191218162402.45610-1-steven.price@arm.com> References: <20191218162402.45610-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as a hole, because it lacks a vma. This means each arch has re-implemented page table walking when needed, for example in the per-arch ptdump walker. Remove the requirement to have a vma in the generic code and add a new function walk_page_range_novma() which ignores the VMAs and simply walks the page tables. Signed-off-by: Steven Price --- include/linux/pagewalk.h | 5 +++++ mm/pagewalk.c | 40 ++++++++++++++++++++++++++++++++-------- 2 files changed, 37 insertions(+), 8 deletions(-) diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index aa6a0b63964e..d5d07f7a9c14 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -73,6 +73,7 @@ enum page_walk_action { * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked (NULL if walking outside vmas) * @action: next action to perform (see enum page_walk_action) + * @no_vma: walk ignoring vmas (vma will always be NULL) * @private: private data for callbacks' usage * * (see the comment on walk_page_range() for more details) @@ -82,12 +83,16 @@ struct mm_walk { struct mm_struct *mm; struct vm_area_struct *vma; enum page_walk_action action; + bool no_vma; void *private; }; int walk_page_range(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private); +int walk_page_range_novma(struct mm_struct *mm, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private); int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private); int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 690af44609e2..d5773465f6da 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -39,7 +39,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, do { again: next = pmd_addr_end(addr, end); - if (pmd_none(*pmd) || !walk->vma) { + if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err) @@ -65,13 +65,16 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, * Check this here so we only break down trans_huge * pages when we _need_ to */ - if (walk->action == ACTION_CONTINUE || + if ((!walk->vma && (pmd_leaf(*pmd) || !pmd_present(*pmd))) || + walk->action == ACTION_CONTINUE || !(ops->pte_entry)) continue; - split_huge_pmd(walk->vma, pmd, addr); - if (pmd_trans_unstable(pmd)) - goto again; + if (walk->vma) { + split_huge_pmd(walk->vma, pmd, addr); + if (pmd_trans_unstable(pmd)) + goto again; + } err = walk_pte_range(pmd, addr, next, walk); if (err) @@ -93,7 +96,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, do { again: next = pud_addr_end(addr, end); - if (pud_none(*pud) || !walk->vma) { + if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) err = ops->pte_hole(addr, next, walk); if (err) @@ -111,11 +114,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, if (walk->action == ACTION_AGAIN) goto again; - if (walk->action == ACTION_CONTINUE || + if ((!walk->vma && (pud_leaf(*pud) || !pud_present(*pud))) || + walk->action == ACTION_CONTINUE || !(ops->pmd_entry || ops->pte_entry)) continue; - split_huge_pud(walk->vma, pud, addr); + if (walk->vma) + split_huge_pud(walk->vma, pud, addr); if (pud_none(*pud)) goto again; @@ -389,6 +394,25 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +int walk_page_range_novma(struct mm_struct *mm, unsigned long start, + unsigned long end, const struct mm_walk_ops *ops, + void *private) +{ + struct mm_walk walk = { + .ops = ops, + .mm = mm, + .private = private, + .no_vma = true + }; + + if (start >= end || !walk.mm) + return -EINVAL; + + lockdep_assert_held(&walk.mm->mmap_sem); + + return __walk_page_range(start, end, &walk); +} + int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private) { -- 2.20.1