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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 44090C433C1 for ; Fri, 26 Mar 2021 14:10:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E8D6619EE for ; Fri, 26 Mar 2021 14:10:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230196AbhCZOKI (ORCPT ); Fri, 26 Mar 2021 10:10:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38753 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230016AbhCZOJg (ORCPT ); Fri, 26 Mar 2021 10:09:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616767769; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z7QwucvE9nb3RtYI6S5g6QloEEtiiTCmIsioM4emDvQ=; b=Z+kRkCuKmAihBi75mpF4KCIB7xOwA6RynJ3dsoD4GGaSRI9D/5x7skHfZIY7xaD/HGbDLD F8hBvZkJJkLF8tLrDuE7705xsCjCp+s34WI9zZEk8WQE8wY5gX/4TnafIpf7jxmZPfilOm Bk4v8P3kKTOnmK3YlP/au+0RnCN7Nww= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-6-BcaHSwW6Nc6esEc7igM1ag-1; Fri, 26 Mar 2021 10:09:25 -0400 X-MC-Unique: BcaHSwW6Nc6esEc7igM1ag-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C793E190D341; Fri, 26 Mar 2021 14:09:23 +0000 (UTC) Received: from [10.36.112.81] (ovpn-112-81.ams2.redhat.com [10.36.112.81]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9235A5D9DE; Fri, 26 Mar 2021 14:09:19 +0000 (UTC) To: Aili Yao , Matthew Wilcox , akpm@linux-foundation.org, naoya.horiguchi@nec.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, yangfeng1@kingsoft.com, sunhao2@kingsoft.com, Oscar Salvador , Mike Kravetz References: <20210317163714.328a038d@alex-virtual-machine> <20a0d078-f49d-54d6-9f04-f6b41dd51e5f@redhat.com> <20210318044600.GJ3420@casper.infradead.org> <20210318133412.12078eb7@alex-virtual-machine> <20210319104437.6f30e80d@alex-virtual-machine> <20210320003516.GC3420@casper.infradead.org> <20210322193318.377c9ce9@alex-virtual-machine> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: [PATCH v5] mm/gup: check page hwposion status for coredump. Message-ID: Date: Fri, 26 Mar 2021 15:09:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210322193318.377c9ce9@alex-virtual-machine> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.03.21 12:33, Aili Yao wrote: > When we do coredump for user process signal, this may be one SIGBUS signal > with BUS_MCEERR_AR or BUS_MCEERR_AO code, which means this signal is > resulted from ECC memory fail like SRAR or SRAO, we expect the memory > recovery work is finished correctly, then the get_dump_page() will not > return the error page as its process pte is set invalid by > memory_failure(). > > But memory_failure() may fail, and the process's related pte may not be > correctly set invalid, for current code, we will return the poison page, > get it dumped, and then lead to system panic as its in kernel code. > > So check the hwpoison status in get_dump_page(), and if TRUE, return NULL. > > There maybe other scenario that is also better to check hwposion status > and not to panic, so make a wrapper for this check, Thanks to David's > suggestion(). > > Link: https://lkml.kernel.org/r/20210319104437.6f30e80d@alex-virtual-machine > Signed-off-by: Aili Yao > Cc: David Hildenbrand > Cc: Matthew Wilcox > Cc: Naoya Horiguchi > Cc: Oscar Salvador > Cc: Mike Kravetz > Cc: Aili Yao > Cc: stable@vger.kernel.org > Signed-off-by: Andrew Morton > --- > mm/gup.c | 4 ++++ > mm/internal.h | 20 ++++++++++++++++++++ > 2 files changed, 24 insertions(+) > > diff --git a/mm/gup.c b/mm/gup.c > index e4c224c..6f7e1aa 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1536,6 +1536,10 @@ struct page *get_dump_page(unsigned long addr) > FOLL_FORCE | FOLL_DUMP | FOLL_GET); > if (locked) > mmap_read_unlock(mm); Thinking again, wouldn't we get -EFAULT from __get_user_pages_locked() when stumbling over a hwpoisoned page? See __get_user_pages_locked()->__get_user_pages()->faultin_page(): handle_mm_fault()->vm_fault_to_errno(), which translates VM_FAULT_HWPOISON to -EFAULT, unless FOLL_HWPOISON is set (-> -EHWPOISON) ? > + > + if (ret == 1 && is_page_hwpoison(page)) > + return NULL; > + > return (ret == 1) ? page : NULL; > } > #endif /* CONFIG_ELF_CORE */ > diff --git a/mm/internal.h b/mm/internal.h > index 25d2b2439..b751cef 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -97,6 +97,26 @@ static inline void set_page_refcounted(struct page *page) > set_page_count(page, 1); > } > > +/* > + * When kernel touch the user page, the user page may be have been marked > + * poison but still mapped in user space, if without this page, the kernel > + * can guarantee the data integrity and operation success, the kernel is > + * better to check the posion status and avoid touching it, be good not to > + * panic, coredump for process fatal signal is a sample case matching this > + * scenario. Or if kernel can't guarantee the data integrity, it's better > + * not to call this function, let kernel touch the poison page and get to > + * panic. > + */ > +static inline bool is_page_hwpoison(struct page *page) > +{ > + if (PageHWPoison(page)) > + return true; > + else if (PageHuge(page) && PageHWPoison(compound_head(page))) > + return true; > + > + return false; > +} > + > extern unsigned long highest_memmap_pfn; > > /* > -- Thanks, David / dhildenb