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=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 7118FC433FE for ; Wed, 15 Sep 2021 17:28:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E9AD661209 for ; Wed, 15 Sep 2021 17:28:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E9AD661209 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 2025E6B0071; Wed, 15 Sep 2021 13:28:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1B184900002; Wed, 15 Sep 2021 13:28:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A08F6B0073; Wed, 15 Sep 2021 13:28:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0026.hostedemail.com [216.40.44.26]) by kanga.kvack.org (Postfix) with ESMTP id EFB5F6B0071 for ; Wed, 15 Sep 2021 13:28:52 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 82E6C181CA323 for ; Wed, 15 Sep 2021 17:28:52 +0000 (UTC) X-FDA: 78590492904.22.D8975C2 Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) by imf07.hostedemail.com (Postfix) with ESMTP id 3A40110000BA for ; Wed, 15 Sep 2021 17:28:52 +0000 (UTC) Received: by mail-ed1-f43.google.com with SMTP id z94so6337379ede.8 for ; Wed, 15 Sep 2021 10:28:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JknZZcds3P+ijp8iLza6R4NMNGNAffXXVQcBCVjKBxA=; b=LOZcdsB35CuvKoDLNkir+xm8Pk907ivp2Jijfe+OqKoX9XFSeFUCa9WYcpE25px2Q7 9ieIdV2R20wM7kH74bbAztIZbquiJpBNXxzViyKjBYU1pOY32NpV5vHHi0bOdhdtBzJW 8OoyJpC4wnRdpFoTki6smMLpagrRs59KyQ1aSmOWyACjybwDf34Djdb/9uEtDJteQrb3 rMse5k5euK/Y+V36Jfd9kjWw3eNbxwMfY3Jety2bZGqpY8wHJHBmOPVlxeQQjwGPLABo PaqEdXR6ZIZyCrxYcScFZmGV4yyn5XVZk3GDyIYPM/u+aJfQGL8zBFGeaUVM87NdClmB x4kw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JknZZcds3P+ijp8iLza6R4NMNGNAffXXVQcBCVjKBxA=; b=dATw+TOLt2eR+JXDpW1fTiaqBYc1Qpea1Am6zyrVmoVES4IUDIDcVh8vtIMLZGfrXB 0I8iUlAllsfAul0hEbcjQlt7goilhW0WnEgAe0IBRl01h+ZRFd0U1FTL9xwMjU3Qj3hh Ak39gvFU7B1vG3un4sId1rAiIkymiQBPTF4ErgOaTW15z9EiNVMj6tJjSCWbVVcsp4j2 vXN7v86JJLkhhz5hdI8vHjdlItxDu5BUYHm+Prx8O8k0RrU+9VuFFHZLgITV0XLcRi+p txU/HDJH9G/Jy0qs0Jca3dBEPP7CJb3PANThnD6QWFMtiMPp0qP+igTAbT8wfgeYLA4C qcuw== X-Gm-Message-State: AOAM5306BvCYf2pgMTmKqDq+DzqO/EdXDzpPsSz+QwcHvS+YmGek+N+k drdV6NBnh7+uxGBj5D9lMXFVE94DLvblQpzwsac= X-Google-Smtp-Source: ABdhPJzFH7fzb9SGKzkJkBGj/B+8nUEWdKuBz9U/Umi6TGAHuLqvjI3XP3GjcmTXBKO4WnSSZayJL/V0+4eq8LCYyb0= X-Received: by 2002:a50:af86:: with SMTP id h6mr1182782edd.283.1631726930917; Wed, 15 Sep 2021 10:28:50 -0700 (PDT) MIME-Version: 1.0 References: <20210914183718.4236-1-shy828301@gmail.com> <20210914183718.4236-2-shy828301@gmail.com> <20210915114613.lo26l64iqjz2qo6a@box.shutemov.name> In-Reply-To: <20210915114613.lo26l64iqjz2qo6a@box.shutemov.name> From: Yang Shi Date: Wed, 15 Sep 2021 10:28:38 -0700 Message-ID: Subject: Re: [PATCH 1/4] mm: filemap: check if any subpage is hwpoisoned for PMD page fault To: "Kirill A. Shutemov" Cc: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Hugh Dickins , "Kirill A. Shutemov" , Matthew Wilcox , Oscar Salvador , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3A40110000BA Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LOZcdsB3; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf07.hostedemail.com: domain of shy828301@gmail.com designates 209.85.208.43 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-Stat-Signature: eaohz1zqqxo5qzcm95wr5kki9rrffmay X-HE-Tag: 1631726932-541677 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 Wed, Sep 15, 2021 at 4:46 AM Kirill A. Shutemov wrote: > > On Tue, Sep 14, 2021 at 11:37:15AM -0700, Yang Shi wrote: > > diff --git a/mm/memory.c b/mm/memory.c > > index 25fc46e87214..1765bf72ed16 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -3920,8 +3920,17 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) > > if (unlikely(!pmd_none(*vmf->pmd))) > > goto out; > > > > - for (i = 0; i < HPAGE_PMD_NR; i++) > > + for (i = 0; i < HPAGE_PMD_NR; i++) { > > + /* > > + * Just backoff if any subpage of a THP is corrupted otherwise > > + * the corrupted page may mapped by PMD silently to escape the > > + * check. This kind of THP just can be PTE mapped. Access to > > + * the corrupted subpage should trigger SIGBUS as expected. > > + */ > > + if (PageHWPoison(page + i)) > > + goto out; > > flush_icache_page(vma, page + i); > > + } > > This is somewhat costly. > > flush_icache_page() is empty on most archs so compiler makes the loop go > away before the change. Also page->flags for most of the pages will not > necessary be hot. Yeah, good point. > > I wounder if we should consider making PG_hwpoison to cover full compound > page. On marking page hwpoison we try to split it and mark relevant base > page, if split fails -- mark full compound page. We need extra bits to record exactly which subpage(s) are poisoned so that the right page can be isolated when splitting. > > As alternative we can have one more flag that indicates that the compound > page contains at least one hwpoisoned base page. We should have enough > space in the first tail page. Yes, actually I was thinking about the same thing too when debugging this problem. I think this approach is more feasible. We could add a new flag in the first tail page just like doublemap which indicates there is/are poisoned subpage(s). It could be cleared when splitting. I will try to implement this in the next version. Thanks a lot for the suggestion. > > -- > Kirill A. Shutemov