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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 A61F2C433DF for ; Tue, 4 Aug 2020 19:42:29 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 82DCA2076E for ; Tue, 4 Aug 2020 19:42:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GmaS8fG9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82DCA2076E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 349922155E; Tue, 4 Aug 2020 19:42:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dYlE6aorjCYS; Tue, 4 Aug 2020 19:42:24 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id A7FFD22179; Tue, 4 Aug 2020 19:42:23 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 8D756C0050; Tue, 4 Aug 2020 19:42:23 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id D6002C004C for ; Tue, 4 Aug 2020 19:42:21 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id C05EA861A7 for ; Tue, 4 Aug 2020 19:42:21 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WWNmdR+VfIwg for ; Tue, 4 Aug 2020 19:42:21 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) by whitealder.osuosl.org (Postfix) with ESMTPS id 0CC9F86234 for ; Tue, 4 Aug 2020 19:42:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596570140; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I1cdcrpSaUyPT7UgxPkoUt6fR2Ifv+AIMispg+nEOrI=; b=GmaS8fG9CGhfMLYGFYWE04zDYbnZTEfJsYcUqVopliWZynLAIyq6KrP7Urxy3F+M51z8Ae JP1g+hFtvS7z634NFQrSpGvVLlsB7JasfcV+6mILaLFowHrPWA7Oz6ZY3ij75Y3raHdZNY vZNF+XKah6MypAuduqwYP+0oU4fPFFQ= 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-390-a5iX9AmiPN6YMOCLCbM3nw-1; Tue, 04 Aug 2020 15:42:16 -0400 X-MC-Unique: a5iX9AmiPN6YMOCLCbM3nw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C4AED1800D42; Tue, 4 Aug 2020 19:42:14 +0000 (UTC) Received: from t480s.redhat.com (ovpn-113-95.ams2.redhat.com [10.36.113.95]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6A51A72E4F; Tue, 4 Aug 2020 19:42:12 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Subject: [PATCH v4 6/6] mm: document semantics of ZONE_MOVABLE Date: Tue, 4 Aug 2020 21:41:42 +0200 Message-Id: <20200804194142.28279-7-david@redhat.com> In-Reply-To: <20200804194142.28279-1-david@redhat.com> References: <20200804194142.28279-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Cc: Pankaj Gupta , Michal Hocko , Baoquan He , "Michael S . Tsirkin" , Mike Rapoport , linux-mm@kvack.org, Andrew Morton , virtualization@lists.linux-foundation.org, Mike Rapoport , Mike Kravetz X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" Let's document what ZONE_MOVABLE means, how it's used, and which special cases we have regarding unmovable pages (memory offlining vs. migration / allocations). Acked-by: Mike Rapoport Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pankaj Gupta Cc: Baoquan He Signed-off-by: David Hildenbrand --- include/linux/mmzone.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index f6f884970511d..3c22aca6cc4f1 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -372,6 +372,41 @@ enum zone_type { */ ZONE_HIGHMEM, #endif + /* + * ZONE_MOVABLE is similar to ZONE_NORMAL, except that it contains + * movable pages with few exceptional cases described below. Main use + * cases for ZONE_MOVABLE are to make memory offlining/unplug more + * likely to succeed, and to locally limit unmovable allocations - e.g., + * to increase the number of THP/huge pages. Notable special cases are: + * + * 1. Pinned pages: (long-term) pinning of movable pages might + * essentially turn such pages unmovable. Memory offlining might + * retry a long time. + * 2. memblock allocations: kernelcore/movablecore setups might create + * situations where ZONE_MOVABLE contains unmovable allocations + * after boot. Memory offlining and allocations fail early. + * 3. Memory holes: we might have a memmap for memory holes, for + * example, if we have sections that are only partially populated. + * Such pages cannot be allocated. Applies only to boot memory, not + * hotplugged memory. Memory offlining and allocations fail early. + * 4. PG_hwpoison pages: while poisoned pages can be skipped during + * memory offlining, such pages cannot be allocated. + * 5. Unmovable PG_offline pages: in paravirtualized environments, + * hotplugged memory blocks might only partially be managed by the + * buddy (e.g., via XEN-balloon, Hyper-V balloon, virtio-mem). The + * parts not manged by the buddy are unmovable PG_offline pages. In + * some cases (virtio-mem), such pages can be skipped during + * memory offlining, however, cannot be moved/allocated. These + * techniques might use alloc_contig_range() to hide previously + * exposed pages from the buddy again (e.g., to implement some sort + * of memory unplug in virtio-mem). + * + * In general, no unmovable allocations that degrade memory offlining + * should end up in ZONE_MOVABLE. Allocators (like alloc_contig_range()) + * have to expect that migrating pages in ZONE_MOVABLE can fail (even + * if has_unmovable_pages() states that there are no unmovable pages, + * there can be false negatives). + */ ZONE_MOVABLE, #ifdef CONFIG_ZONE_DEVICE ZONE_DEVICE, -- 2.26.2 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization