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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21B9FC433EF for ; Wed, 16 Mar 2022 06:43:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A5B288D0002; Wed, 16 Mar 2022 02:43:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A0B368D0001; Wed, 16 Mar 2022 02:43:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F9628D0002; Wed, 16 Mar 2022 02:43:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 7C13B8D0001 for ; Wed, 16 Mar 2022 02:43:05 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3DCA723F18 for ; Wed, 16 Mar 2022 06:43:05 +0000 (UTC) X-FDA: 79249307130.10.20EC468 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf17.hostedemail.com (Postfix) with ESMTP id 92DE640018 for ; Wed, 16 Mar 2022 06:43:04 +0000 (UTC) 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 A73C31515; Tue, 15 Mar 2022 23:43:03 -0700 (PDT) Received: from [10.163.34.65] (unknown [10.163.34.65]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1E4323F766; Tue, 15 Mar 2022 23:43:01 -0700 (PDT) Message-ID: <93302a47-9fda-25c7-4212-41b8dd027696@arm.com> Date: Wed, 16 Mar 2022 12:13:07 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] mm: add access/dirty bit on numa page fault Content-Language: en-US To: Bibo Mao , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220316010836.1137084-1-maobibo@loongson.cn> From: Anshuman Khandual In-Reply-To: <20220316010836.1137084-1-maobibo@loongson.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 92DE640018 X-Stat-Signature: o46xudyzk5irxr3w631gzajbf8owg9cp X-Rspam-User: Authentication-Results: imf17.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf17.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com X-HE-Tag: 1647412984-252306 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/16/22 06:38, Bibo Mao wrote: > During numa page fault, dirty bit can be added for old pte if > fail to migrate on write fault. And if it succeeds to migrate, > access bit can be added for migrated new pte, also dirty bit > can be added for write fault. The current code does not set the access and dirty bits when ever applicable i.e on FAULT_FLAG_WRITE, on the pte (old if migration fails, new if migration succeeds) ? Did not this cause any problem earlier ? I am wondering how this might have gone unnoticed. > > Signed-off-by: Bibo Mao > --- > mm/memory.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/mm/memory.c b/mm/memory.c > index c125c4969913..65813bec9c06 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4404,6 +4404,22 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > if (migrate_misplaced_page(page, vma, target_nid)) { > page_nid = target_nid; > flags |= TNF_MIGRATED; > + > + /* > + * update pte entry with access bit, and dirty bit for > + * write fault > + */ > + spin_lock(vmf->ptl); > + pte = *vmf->pte; > + pte = pte_mkyoung(pte); > + if (was_writable) { > + pte = pte_mkwrite(pte); > + if (vmf->flags & FAULT_FLAG_WRITE) > + pte = pte_mkdirty(pte); > + } > + set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); > + update_mmu_cache(vma, vmf->address, vmf->pte); > + pte_unmap_unlock(vmf->pte, vmf->ptl); > } else { > flags |= TNF_MIGRATE_FAIL; > vmf->pte = pte_offset_map(vmf->pmd, vmf->address); > @@ -4427,8 +4443,11 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte); > pte = pte_modify(old_pte, vma->vm_page_prot); > pte = pte_mkyoung(pte); > - if (was_writable) > + if (was_writable) { > pte = pte_mkwrite(pte); > + if (vmf->flags & FAULT_FLAG_WRITE) > + pte = pte_mkdirty(pte); > + } > ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte); > update_mmu_cache(vma, vmf->address, vmf->pte); > pte_unmap_unlock(vmf->pte, vmf->ptl);