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 F378FC43334 for ; Wed, 8 Jun 2022 12:57:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 11E1B8D0021; Wed, 8 Jun 2022 08:57:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0CD0E6B00A3; Wed, 8 Jun 2022 08:57:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED6F78D0021; Wed, 8 Jun 2022 08:57:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id DB59C6B009E for ; Wed, 8 Jun 2022 08:57:31 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id A681B81245 for ; Wed, 8 Jun 2022 12:57:31 +0000 (UTC) X-FDA: 79555069902.01.BAF540C Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf10.hostedemail.com (Postfix) with ESMTP id 0B501C003A for ; Wed, 8 Jun 2022 12:57:29 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LJ6f04PDDz1KBns; Wed, 8 Jun 2022 20:55:36 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 8 Jun 2022 20:57:25 +0800 Subject: Re: [PATCH v1 5/5] mm, hwpoison: enable memory error handling on 1GB hugepage To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: Naoya Horiguchi , Andrew Morton , David Hildenbrand , Mike Kravetz , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , "linux-kernel@vger.kernel.org" , Linux-MM References: <20220602050631.771414-1-naoya.horiguchi@linux.dev> <20220602050631.771414-6-naoya.horiguchi@linux.dev> <20220608061635.GA1413099@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: <5743855d-8f22-0d82-56c0-1ab61ad431b7@huawei.com> Date: Wed, 8 Jun 2022 20:57:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220608061635.GA1413099@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 0B501C003A X-Stat-Signature: 4uo7m1p898oqhjosyn1szzokmsnd88d3 X-Rspam-User: Authentication-Results: imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-HE-Tag: 1654693049-904882 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 2022/6/8 14:16, HORIGUCHI NAOYA(堀口 直也) wrote: > On Tue, Jun 07, 2022 at 10:11:24PM +0800, Miaohe Lin wrote: >> On 2022/6/2 13:06, Naoya Horiguchi wrote: >>> From: Naoya Horiguchi >>> >>> Now error handling code is prepared, so remove the blocking code and >>> enable memory error handling on 1GB hugepage. >>> >> >> I'm nervous about this change. It seems there are many code paths not awared of pud swap entry. >> I browsed some of them: >> apply_to_pud_range called from apply_to_page_range: >> >> apply_to_pud_range: >> next = pud_addr_end(addr, end); >> if (pud_none(*pud) && !create) >> continue; >> if (WARN_ON_ONCE(pud_leaf(*pud))) >> return -EINVAL; >> if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { >> if (!create) >> continue; >> pud_clear_bad(pud); >> } >> err = apply_to_pmd_range(mm, pud, addr, next, >> fn, data, create, mask); >> >> For !pud_present case, it will mostly reach apply_to_pmd_range and call pmd_offset on it. And invalid >> pointer will be de-referenced. > > apply_to_pmd_range() has BUG_ON(pud_huge(*pud)) and apply_to_pte_range() has > BUG_ON(pmd_huge(*pmd)), so this page table walking code seems to not expect > to handle pmd/pud level mapping. Yes, you're right. These functions are not intended to handle pmd/pud level mapping. > >> >> Another example might be copy_pud_range and so on. So I think it might not be prepared to enable the >> 1GB hugepage or all of these places should be fixed? > > I think that most of page table walker for user address space should first > check is_vm_hugetlb_page() and call hugetlb specific walking code for vma > with VM_HUGETLB. > copy_page_range() is a good example. It calls copy_hugetlb_page_range() > for vma with VM_HUGETLB and the function should support hwpoison entry. > But I feel that I need testing for confirmation. Sorry, I missed it should be called from hugetlb variants. > > And I'm not sure that all other are prepared for non-present pud-mapping, > so I'll need somehow code inspection and testing for each. I browsed the code again, there still might be some problematic code paths: 1.For follow_pud_mask, !pud_present will mostly reach follow_pmd_mask(). This can be called for hugetlb page. (Note gup_pud_range is fixed at 15494520b776 ("mm: fix gup_pud_range")) 2.Even for huge_pte_alloc, pud_offset will be called in pud_alloc. So pudp will be an invalid pointer. And it will be de-referenced later. I hope I'm not miss something again this time. ;) > > Thanks, > Naoya Horiguchi Thanks! >