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=-13.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B97A6C64E7C for ; Wed, 2 Dec 2020 09:22:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71AEC22203 for ; Wed, 2 Dec 2020 09:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729213AbgLBJWJ (ORCPT ); Wed, 2 Dec 2020 04:22:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:40803 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729107AbgLBJWH (ORCPT ); Wed, 2 Dec 2020 04:22:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606900841; 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=sQQdBNNqgVntbNPasbENMCveCDK2DYJNqimJozaTDkQ=; b=W1jx7M5pFW9zxHs9TTQSEdOPHpgq7w6waR/cYvR7NUdnrGnZzpIqYKTILju2HsCt3P4HKg fTgZPOGcAjny1EbCoXGciNRZiEo8tUcN+Ma9pkh762jhrJLnMhpu+QzbqkLsBd5YI2dHZF nSW0fHQVePW8mIDuKgxEDZbNFaMJ90Q= 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-302-J1BxoSlzNnGLzDY8zAafEg-1; Wed, 02 Dec 2020 04:20:39 -0500 X-MC-Unique: J1BxoSlzNnGLzDY8zAafEg-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id C79CA858190; Wed, 2 Dec 2020 09:20:37 +0000 (UTC) Received: from [10.36.113.108] (ovpn-113-108.ams2.redhat.com [10.36.113.108]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7476D19C47; Wed, 2 Dec 2020 09:20:36 +0000 (UTC) Subject: Re: [RFC V2 1/3] mm/hotplug: Prevalidate the address range being added with platform To: Anshuman Khandual , linux-mm@kvack.org, akpm@linux-foundation.org Cc: linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <1606706992-26656-1-git-send-email-anshuman.khandual@arm.com> <1606706992-26656-2-git-send-email-anshuman.khandual@arm.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <864c701a-4391-f768-1b95-1992e21835a2@redhat.com> Date: Wed, 2 Dec 2020 10:20:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <1606706992-26656-2-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30.11.20 04:29, Anshuman Khandual wrote: > This introduces memhp_range_allowed() which can be called in various memory > hotplug paths to prevalidate the address range which is being added, with > the platform. Then memhp_range_allowed() calls memhp_get_pluggable_range() > which provides applicable address range depending on whether linear mapping > is required or not. For ranges that require linear mapping, it calls a new > arch callback arch_get_mappable_range() which the platform can override. So > the new callback, in turn provides the platform an opportunity to configure > acceptable memory hotplug address ranges in case there are constraints. > > This mechanism will help prevent platform specific errors deep down during > hotplug calls. This drops now redundant check_hotplug_memory_addressable() > check in __add_pages(). > [...] > /* > * Reasonably generic function for adding memory. It is > * expected that archs that support memory hotplug will > @@ -317,10 +304,6 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages, > if (WARN_ON_ONCE(!params->pgprot.pgprot)) > return -EINVAL; > > - err = check_hotplug_memory_addressable(pfn, nr_pages); > - if (err) > - return err; > - I was wondering if we should add a VM_BUG_ON(!memhp_range_allowed()) here to make it clearer that callers are expected to check that first. Maybe an other places as well (e.g., arch code where we remove the original checks) [...] > #endif /* CONFIG_MEMORY_HOTREMOVE */ > diff --git a/mm/memremap.c b/mm/memremap.c > index 16b2fb482da1..26c1825756cc 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -185,6 +185,7 @@ static void dev_pagemap_percpu_release(struct percpu_ref *ref) > static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, > int range_id, int nid) > { > + const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE; > struct range *range = &pgmap->ranges[range_id]; > struct dev_pagemap *conflict_pgmap; > int error, is_ram; > @@ -230,6 +231,9 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, > if (error) > goto err_pfn_remap; > > + if (!memhp_range_allowed(range->start, range_len(range), !is_private)) > + goto err_pfn_remap; > + > mem_hotplug_begin(); > > /* > @@ -243,7 +247,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, > * the CPU, we do want the linear mapping and thus use > * arch_add_memory(). > */ > - if (pgmap->type == MEMORY_DEVICE_PRIVATE) { > + if (is_private) { > error = add_pages(nid, PHYS_PFN(range->start), > PHYS_PFN(range_len(range)), params); > } else { > In general, LGTM. -- Thanks, David / dhildenb