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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE96FC4332F for ; Mon, 12 Dec 2022 02:37:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230400AbiLLCgy (ORCPT ); Sun, 11 Dec 2022 21:36:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230500AbiLLCgw (ORCPT ); Sun, 11 Dec 2022 21:36:52 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E65ABC97 for ; Sun, 11 Dec 2022 18:36:51 -0800 (PST) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4NVlyp5XB3zqSPQ; Mon, 12 Dec 2022 10:32:34 +0800 (CST) Received: from [10.174.151.185] (10.174.151.185) 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 15.1.2375.34; Mon, 12 Dec 2022 10:36:49 +0800 Subject: Re: [PATCH -next v2] mm: hwposion: support recovery from ksm_might_need_to_copy() To: Kefeng Wang CC: , , HORIGUCHI NAOYA , Andrew Morton , Linux-MM References: <20221209021525.196276-1-wangkefeng.wang@huawei.com> <20221209072801.193221-1-wangkefeng.wang@huawei.com> From: Miaohe Lin Message-ID: <342f4d3f-7347-1615-7d63-cbdef4872629@huawei.com> Date: Mon, 12 Dec 2022 10:36:48 +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: <20221209072801.193221-1-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.151.185] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/12/9 15:28, Kefeng Wang wrote: > When the kernel copy a page from ksm_might_need_to_copy(), but runs > into an uncorrectable error, it will crash since poisoned page is > consumed by kernel, this is similar to Copy-on-write poison recovery, > When an error is detected during the page copy, return VM_FAULT_HWPOISON, > which help us to avoid system crash. Note, memory failure on a KSM > page will be skipped, but still call memory_failure_queue() to be > consistent with general memory failure process. Thanks for your patch. > > Signed-off-by: Kefeng Wang > --- > v2: fix type error > > mm/ksm.c | 8 ++++++-- > mm/memory.c | 3 +++ > mm/swapfile.c | 2 +- > 3 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index dd02780c387f..83e2f74ae7da 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2629,8 +2629,12 @@ struct page *ksm_might_need_to_copy(struct page *page, > new_page = NULL; > } > if (new_page) { > - copy_user_highpage(new_page, page, address, vma); > - > + if (copy_mc_user_highpage(new_page, page, address, vma)) { > + put_page(new_page); > + new_page = ERR_PTR(-EHWPOISON); > + memory_failure_queue(page_to_pfn(page), 0); > + return new_page; > + } > SetPageDirty(new_page); > __SetPageUptodate(new_page); > __SetPageLocked(new_page); > diff --git a/mm/memory.c b/mm/memory.c > index aad226daf41b..5b2c137dfb2a 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3840,6 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > if (unlikely(!page)) { > ret = VM_FAULT_OOM; > goto out_page; > + } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) { > + ret = VM_FAULT_HWPOISON; > + goto out_page; > } > folio = page_folio(page); > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 908a529bca12..d479811bc311 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1767,7 +1767,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > > swapcache = page; > page = ksm_might_need_to_copy(page, vma, addr); > - if (unlikely(!page)) > + if (IS_ERR_OR_NULL(page)) IMHO, it might be better to install a hwpoison entry here. Or later swapoff ops will trigger the uncorrectable error again? Thanks, Miaohe Lin