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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 3DC49CA9EA0 for ; Fri, 18 Oct 2019 11:05:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0CCD021D7C for ; Fri, 18 Oct 2019 11:05:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CCD021D7C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 864B78E0006; Fri, 18 Oct 2019 07:05:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 814CC8E0003; Fri, 18 Oct 2019 07:05:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7042F8E0006; Fri, 18 Oct 2019 07:05:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0178.hostedemail.com [216.40.44.178]) by kanga.kvack.org (Postfix) with ESMTP id 493738E0003 for ; Fri, 18 Oct 2019 07:05:14 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id E1395182030A5 for ; Fri, 18 Oct 2019 11:05:13 +0000 (UTC) X-FDA: 76056623706.01.song74_67d132269f310 X-HE-Tag: song74_67d132269f310 X-Filterd-Recvd-Size: 4203 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Fri, 18 Oct 2019 11:05:13 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 51730307B194; Fri, 18 Oct 2019 11:05:12 +0000 (UTC) Received: from [10.36.118.23] (unknown [10.36.118.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id F367A19C77; Fri, 18 Oct 2019 11:05:10 +0000 (UTC) Subject: Re: memory offline infinite loop after soft offline From: David Hildenbrand To: Michal Hocko Cc: Naoya Horiguchi , Qian Cai , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Mike Kravetz References: <1570829564.5937.36.camel@lca.pw> <20191014083914.GA317@dhcp22.suse.cz> <20191017093410.GA19973@hori.linux.bs1.fc.nec.co.jp> <20191017100106.GF24485@dhcp22.suse.cz> <1571335633.5937.69.camel@lca.pw> <20191017182759.GN24485@dhcp22.suse.cz> <20191018021906.GA24978@hori.linux.bs1.fc.nec.co.jp> <33946728-bdeb-494a-5db8-e279acebca47@redhat.com> <20191018082459.GE5017@dhcp22.suse.cz> <20191018085528.GG5017@dhcp22.suse.cz> <3ac0ad7a-7dd2-c851-858d-2986fa8d44b6@redhat.com> Organization: Red Hat GmbH Message-ID: <85f944c7-62b8-0784-2f1f-e762b974d317@redhat.com> Date: Fri, 18 Oct 2019 13:05:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <3ac0ad7a-7dd2-c851-858d-2986fa8d44b6@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 18 Oct 2019 11:05:12 +0000 (UTC) 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 18.10.19 13:00, David Hildenbrand wrote: > On 18.10.19 10:55, Michal Hocko wrote: >> On Fri 18-10-19 10:38:21, David Hildenbrand wrote: >>> On 18.10.19 10:24, Michal Hocko wrote: >>>> On Fri 18-10-19 10:13:36, David Hildenbrand wrote: >>>> [...] >>>>> However, if the compound page spans multiple pageblocks >>>> >>>> Although hugetlb pages spanning pageblocks are possible this shouldn't >>>> matter in__test_page_isolated_in_pageblock because this function doesn't >>>> really operate on pageblocks as the name suggests. It is simply >>>> traversing all valid RAM ranges (see walk_system_ram_range). >>> >>> As long as the hugepages don't span memory blocks/sections, you are right. I >>> have no experience with gigantic pages in this regard. >> >> They can clearly span sections (1GB is larger than 128MB). Why do you >> think it matters actually? walk_system_ram_range walks RAM ranges and no >> allocation should span holes in RAM right? >> > > Let's explore what I was thinking. If we can agree that any compound > page is always aligned to its size , then what I tell here is not > applicable. I know it is true for gigantic pages. > > Some extreme example to clarify > > [ memory block 0 (128MB) ][ memory block 1 (128MB) ] > [ compound page (128MB) ] > > If you would offline memory block 1, and you detect PG_offline on the s/PG_offline/PG_hwpoison/ :) > first page of that memory block (PageHWPoison(compound_head(page))), you > would jump over the whole memory block (pfn += 1 << > compound_order(page)), leaving 64MB of the memory block unchecked. > > Again, if any compound page has the alignment restrictions (PFN of head > aligned to 1 << compound_order(page)), this is not possible. > > > If it is, however, possible, the "clean" thing would be to only jump > over the remaining part of the compound page, e.g., something like > > pfn += (1 << compound_order(page)) - (page - compound_head(page))); > > > -- Thanks, David / dhildenb