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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 C0039C31E49 for ; Sun, 16 Jun 2019 03:58:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81D8B20866 for ; Sun, 16 Jun 2019 03:58:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727137AbfFPDuT (ORCPT ); Sat, 15 Jun 2019 23:50:19 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41128 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726883AbfFPDuS (ORCPT ); Sat, 15 Jun 2019 23:50:18 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5G3lLMS125015 for ; Sat, 15 Jun 2019 23:50:17 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0b-001b2d01.pphosted.com with ESMTP id 2t5dwx8ecc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Sat, 15 Jun 2019 23:50:16 -0400 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Sun, 16 Jun 2019 04:50:12 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5G3oBUR49348710 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 16 Jun 2019 03:50:11 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 51C71AE057; Sun, 16 Jun 2019 03:50:11 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8981FAE04D; Sun, 16 Jun 2019 03:50:09 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.85.86.48]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Sun, 16 Jun 2019 03:50:09 +0000 (GMT) X-Mailer: emacs 26.2 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Dan Williams Cc: Oscar Salvador , Qian Cai , Andrew Morton , Linux MM , Linux Kernel Mailing List , jmoyer Subject: Re: [PATCH -next] mm/hotplug: skip bad PFNs from pfn_to_online_page() In-Reply-To: References: <1560366952-10660-1-git-send-email-cai@lca.pw> <1560376072.5154.6.camel@lca.pw> <87lfy4ilvj.fsf@linux.ibm.com> <20190614153535.GA9900@linux> Date: Sun, 16 Jun 2019 09:19:42 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19061603-0016-0000-0000-000002897078 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061603-0017-0000-0000-000032E6B591 Message-Id: <87imt6i3zd.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-16_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=27 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906160035 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > On Fri, Jun 14, 2019 at 9:18 AM Aneesh Kumar K.V > wrote: >> >> On 6/14/19 9:05 PM, Oscar Salvador wrote: >> > On Fri, Jun 14, 2019 at 02:28:40PM +0530, Aneesh Kumar K.V wrote: >> >> Can you check with this change on ppc64. I haven't reviewed this series yet. >> >> I did limited testing with change . Before merging this I need to go >> >> through the full series again. The vmemmap poplulate on ppc64 needs to >> >> handle two translation mode (hash and radix). With respect to vmemap >> >> hash doesn't setup a translation in the linux page table. Hence we need >> >> to make sure we don't try to setup a mapping for a range which is >> >> arleady convered by an existing mapping. >> >> >> >> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c >> >> index a4e17a979e45..15c342f0a543 100644 >> >> --- a/arch/powerpc/mm/init_64.c >> >> +++ b/arch/powerpc/mm/init_64.c >> >> @@ -88,16 +88,23 @@ static unsigned long __meminit vmemmap_section_start(unsigned long page) >> >> * which overlaps this vmemmap page is initialised then this page is >> >> * initialised already. >> >> */ >> >> -static int __meminit vmemmap_populated(unsigned long start, int page_size) >> >> +static bool __meminit vmemmap_populated(unsigned long start, int page_size) >> >> { >> >> unsigned long end = start + page_size; >> >> start = (unsigned long)(pfn_to_page(vmemmap_section_start(start))); >> >> >> >> - for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page))) >> >> - if (pfn_valid(page_to_pfn((struct page *)start))) >> >> - return 1; >> >> + for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page))) { >> >> >> >> - return 0; >> >> + struct mem_section *ms; >> >> + unsigned long pfn = page_to_pfn((struct page *)start); >> >> + >> >> + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) >> >> + return 0; >> > >> > I might be missing something, but is this right? >> > Having a section_nr above NR_MEM_SECTIONS is invalid, but if we return 0 here, >> > vmemmap_populate will go on and populate it. >> >> I should drop that completely. We should not hit that condition at all. >> I will send a final patch once I go through the full patch series making >> sure we are not breaking any ppc64 details. >> >> Wondering why we did the below >> >> #if defined(ARCH_SUBSECTION_SHIFT) >> #define SUBSECTION_SHIFT (ARCH_SUBSECTION_SHIFT) >> #elif defined(PMD_SHIFT) >> #define SUBSECTION_SHIFT (PMD_SHIFT) >> #else >> /* >> * Memory hotplug enabled platforms avoid this default because they >> * either define ARCH_SUBSECTION_SHIFT, or PMD_SHIFT is a constant, but >> * this is kept as a backstop to allow compilation on >> * !ARCH_ENABLE_MEMORY_HOTPLUG archs. >> */ >> #define SUBSECTION_SHIFT 21 >> #endif >> >> why not >> >> #if defined(ARCH_SUBSECTION_SHIFT) >> #define SUBSECTION_SHIFT (ARCH_SUBSECTION_SHIFT) >> #else >> #define SUBSECTION_SHIFT SECTION_SHIFT >> #endif >> >> ie, if SUBSECTION is not supported by arch we have one sub-section per >> section? > > A couple comments: > > The only reason ARCH_SUBSECTION_SHIFT exists is because PMD_SHIFT on > PowerPC was a non-constant value. However, I'm planning to remove the > distinction in the next rev of the patches. Jeff rightly points out > that having a variable subsection size per arch will lead to > situations where persistent memory namespaces are not portable across > archs. So I plan to just make SUBSECTION_SHIFT 21 everywhere. What is the dependency between subsection and pageblock_order? Shouldn't subsection size >= pageblock size? We do have pageblock size drived from HugeTLB size. -aneesh