From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE37D2901 for ; Sun, 5 May 2024 07:00:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714892433; cv=none; b=MmKDYeuHaoenBkbJjzue6i5ohkRPzlt33mtrwTGPnzvwQ1VSYt3meroVh429uo/0awht9yjK/bI+i/4HrhbOFDhLaxvpmG2Hl5+EeAHxmTPua/PEEiQ7N4d+IjGPuLLnq6iDKCW9gmRzCqr2cu28XpFDBRoU3JDIrj10JG0NgQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714892433; c=relaxed/simple; bh=Ti0NDrKYBP9Uy6IPNOgqqiIxHOwl6ehcRPGqiyLSeMI=; h=Subject:To:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=OXCMfhcapwbWwF1RrUzvLlmIZiJLb44pRJelgMX6iQP8VtWDKW7iTOsd0UIeiw5cKBEK+hXUtVxwcvADaHX6LwburKDFO9apvfknRplHKjcyn9H/ags478EQAH+JbDFy6WUnt/7aP7A/LDIajO6beWIGqGHc952pdoQ8rwv25E0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4VXFl32tWdzcdSC; Sun, 5 May 2024 14:59:11 +0800 (CST) Received: from canpemm500002.china.huawei.com (unknown [7.192.104.244]) by mail.maildlp.com (Postfix) with ESMTPS id 10DC318007A; Sun, 5 May 2024 15:00:21 +0800 (CST) Received: from [10.173.135.154] (10.173.135.154) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Sun, 5 May 2024 15:00:20 +0800 Subject: Re: [PATCH 3/3] mm/memory-failure: send SIGBUS in the event of thp split fail To: Jane Chu , , , , References: <20240501232458.3919593-1-jane.chu@oracle.com> <20240501232458.3919593-4-jane.chu@oracle.com> From: Miaohe Lin Message-ID: <038cffc0-e027-b518-460f-40099819c588@huawei.com> Date: Sun, 5 May 2024 15:00:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240501232458.3919593-4-jane.chu@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) On 2024/5/2 7:24, Jane Chu wrote: > When handle hwpoison in a GUP longterm pin'ed thp page, > try_to_split_thp_page() will fail. And at this point, there is little else > the kernel could do except sending a SIGBUS to the user process, thus > give it a chance to recover. > > Signed-off-by: Jane Chu Thanks for your patch. Some comments below. > --- > mm/memory-failure.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 7fcf182abb96..67f4d24a98e7 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -2168,6 +2168,37 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, > return rc; > } > > +/* > + * The calling condition is as such: thp split failed, page might have > + * been GUP longterm pinned, not much can be done for recovery. > + * But a SIGBUS should be delivered with vaddr provided so that the user > + * application has a chance to recover. Also, application processes' > + * election for MCE early killed will be honored. > + */ > +static int kill_procs_now(struct page *p, unsigned long pfn, int flags, > + struct page *hpage) > +{ > + struct folio *folio = page_folio(hpage); > + LIST_HEAD(tokill); > + int res = -EHWPOISON; > + > + /* deal with user pages only */ > + if (PageReserved(p) || PageSlab(p) || PageTable(p) || PageOffline(p)) > + res = -EBUSY; > + if (!(PageLRU(hpage) || PageHuge(p))) > + res = -EBUSY; Above checks seems unneeded. We already know it's thp? > + > + if (res == -EHWPOISON) { > + collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED); > + kill_procs(&tokill, true, pfn, flags); > + } > + > + if (flags & MF_COUNT_INCREASED) > + put_page(p); This if block is broken. put_page() has been done when try_to_split_thp_page() fails? > + action_result is missing? > + return res; > +} > + > /** > * memory_failure - Handle memory failure of a page. > * @pfn: Page Number of the corrupted page > @@ -2297,6 +2328,11 @@ int memory_failure(unsigned long pfn, int flags) > */ > SetPageHasHWPoisoned(hpage); > if (try_to_split_thp_page(p) < 0) { Should hwpoison_filter() be called in this case? > + if (flags & MF_ACTION_REQUIRED) { > + pr_err("%#lx: thp split failed\n", pfn); > + res = kill_procs_now(p, pfn, flags, hpage); Can we use hwpoison_user_mappings() directly here? Thanks. . > + goto unlock_mutex; > + } > res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED); > goto unlock_mutex; > } >