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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 815FAC35250 for ; Sun, 9 Feb 2020 10:49:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5206E20733 for ; Sun, 9 Feb 2020 10:49:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SqratGxp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727787AbgBIKs6 (ORCPT ); Sun, 9 Feb 2020 05:48:58 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:53831 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727768AbgBIKsz (ORCPT ); Sun, 9 Feb 2020 05:48:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581245334; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=avDH489Kezk0JZkoC0zLQWdCP4dLpS7AfZ6UHFu6JUE=; b=SqratGxpX2husjUsJtOrPcaMAmX3pVrYpfv60bBKFYSI6U4XlE+fRxqM0jl5eKKS2AcNWJ U/iuezfVpWSSWea+iFfeEj98g7COLbdY0ypds5rFoUoSCG0OjQQBCEPAaANf+Q52PWMYGZ TatThlNJsTAXFClIKZ0iOXvtSec89p8= 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-2-Y1RO4sIjPpW_7FwABGULVA-1; Sun, 09 Feb 2020 05:48:50 -0500 X-MC-Unique: Y1RO4sIjPpW_7FwABGULVA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3618913E5; Sun, 9 Feb 2020 10:48:49 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-31.pek2.redhat.com [10.72.12.31]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6A8E410013A7; Sun, 9 Feb 2020 10:48:46 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, dan.j.williams@intel.com, richardw.yang@linux.intel.com, david@redhat.com, bhe@redhat.com Subject: [PATCH 5/7] mm/sparse.c: update code comment about section activate/deactivate Date: Sun, 9 Feb 2020 18:48:24 +0800 Message-Id: <20200209104826.3385-6-bhe@redhat.com> In-Reply-To: <20200209104826.3385-1-bhe@redhat.com> References: <20200209104826.3385-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's helpful to note that sub-section is only supported in SPARSEMEM_VMEMMAP case, but not in SPARSEMEM|!VMEMMAP case. Add sentences into the code comment above sparse_add_section. And move the code comments inside section_deactivate() to be above it, this makes code cleaner. Signed-off-by: Baoquan He --- mm/sparse.c | 40 +++++++++++++++++++++++----------------- 1 file changed, 23 insertions(+), 17 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index 36e6565ec67e..a7e78bfe0dce 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -809,6 +809,23 @@ static void free_map_bootmem(struct page *memmap) } #endif /* CONFIG_SPARSEMEM_VMEMMAP */ +/* + * To deactivate a memory region, there are 3 cases across two + * two configurations (SPARSEMEM_VMEMMAP={y,n}): + * + * 1/ deactivation of a partial hot-added section (only possible + * in the SPARSEMEM_VMEMMAP=y case). + * a/ section was present at memory init + * b/ section was hot-added post memory init + * 2/ deactivation of a complete hot-added section + * 3/ deactivation of a complete section from memory init + * + * For 1/, when subsection_map does not empty we will not be + * freeing the usage map, but still need to free the vmemmap + * range. + * + * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified + */ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, struct vmem_altmap *altmap) { @@ -821,23 +838,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, rc = clear_subsection_map(pfn, nr_pages); if(IS_ERR_VALUE((unsigned long)rc)) return; - /* - * There are 3 cases to handle across two configurations - * (SPARSEMEM_VMEMMAP={y,n}): - * - * 1/ deactivation of a partial hot-added section (only possible - * in the SPARSEMEM_VMEMMAP=y case). - * a/ section was present at memory init - * b/ section was hot-added post memory init - * 2/ deactivation of a complete hot-added section - * 3/ deactivation of a complete section from memory init - * - * For 1/, when subsection_map does not empty we will not be - * freeing the usage map, but still need to free the vmemmap - * range. - * - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified - */ + if (!rc) { unsigned long section_nr = pfn_to_section_nr(pfn); @@ -913,6 +914,11 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, * * This is only intended for hotplug. * + * Note that the added memory region is either section aligned, or + * sub-section aligned. The sub-section aligned region can only be + * hot added in SPARSEMEM_VMEMMAP case, please refer to ZONE_DEVICE + * part of memory-model.rst for more details. + * * Return: * * 0 - On success. * * -EEXIST - Section has been present. -- 2.17.2