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=-17.8 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,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 608DAC433DB for ; Tue, 5 Jan 2021 16:58:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB8DB22CB9 for ; Tue, 5 Jan 2021 16:58:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB8DB22CB9 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 504D48D0088; Tue, 5 Jan 2021 11:58:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4B3FD8D006E; Tue, 5 Jan 2021 11:58:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 354298D0088; Tue, 5 Jan 2021 11:58:27 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id 1ED7F8D006E for ; Tue, 5 Jan 2021 11:58:27 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id DDE88181AC9C6 for ; Tue, 5 Jan 2021 16:58:26 +0000 (UTC) X-FDA: 77672329812.10.comb30_3e144fc274da Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin10.hostedemail.com (Postfix) with ESMTP id AB15916A0B9 for ; Tue, 5 Jan 2021 16:58:26 +0000 (UTC) X-HE-Tag: comb30_3e144fc274da X-Filterd-Recvd-Size: 3424 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 Jan 2021 16:58:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609865905; 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=IntXvGqGvaLGOykTrK+a/7qDvmx7IE1kSq/BSyj62uU=; b=D7nbqmCpWeO7sprHzXxzyA1iErzQ4BhfTc+SvRJeIJnZ0RMu0GekB0Iim2putpj3tKnKsm Nudvn7WDbQiicslUbRvX7aIMwHBApLsYtdBKUluTJNlsFnMtuJt2Z6kJqINwew2tQby23S kl4/LFFGOdhRGbqpMyaUwj3NxHfV8PY= 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-389-o6N64yxmOGm0B83XZCmrlw-1; Tue, 05 Jan 2021 11:58:21 -0500 X-MC-Unique: o6N64yxmOGm0B83XZCmrlw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C85D284639D; Tue, 5 Jan 2021 16:58:19 +0000 (UTC) Received: from [10.36.114.117] (ovpn-114-117.ams2.redhat.com [10.36.114.117]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4E9D95F9B8; Tue, 5 Jan 2021 16:58:17 +0000 (UTC) Subject: Re: [PATCH 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one To: Muchun Song , mike.kravetz@oracle.com, akpm@linux-foundation.org Cc: hillf.zj@alibaba-inc.com, n-horiguchi@ah.jp.nec.com, ak@linux.intel.com, yongjun_wei@trendmicro.com.cn, mhocko@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210104065843.5658-1-songmuchun@bytedance.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Tue, 5 Jan 2021 17:58:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210104065843.5658-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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 04.01.21 07:58, Muchun Song wrote: > If the refcount is one when it is migrated, it means that the page > was freed from under us. So we are done and do not need to migrate. > > Signed-off-by: Muchun Song > --- > mm/migrate.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 4385f2fb5d18..a6631c4eb6a6 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1279,6 +1279,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > return -ENOSYS; > } > > + if (page_count(hpage) == 1) { > + /* page was freed from under us. So we are done. */ > + putback_active_hugepage(hpage); > + return MIGRATEPAGE_SUCCESS; > + } > + > new_hpage = get_new_page(hpage, private); > if (!new_hpage) > return -ENOMEM; > This series seems to fix quite some important cases (thanks). Do we want to cc stable some/all? -- Thanks, David / dhildenb