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=-12.7 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 2EF94C43461 for ; Tue, 8 Sep 2020 10:26:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B1B41208C7 for ; Tue, 8 Sep 2020 10:26:33 +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="R9FP132l" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B1B41208C7 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 4A7FF6B0002; Tue, 8 Sep 2020 06:26:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 463CA8E0001; Tue, 8 Sep 2020 06:26:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2D3D56B005A; Tue, 8 Sep 2020 06:26:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0034.hostedemail.com [216.40.44.34]) by kanga.kvack.org (Postfix) with ESMTP id 14D066B0002 for ; Tue, 8 Sep 2020 06:26:33 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CDC561EFF for ; Tue, 8 Sep 2020 10:26:32 +0000 (UTC) X-FDA: 77239515024.15.lake70_1004bfe270d4 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id A3DCA1814B0C1 for ; Tue, 8 Sep 2020 10:26:32 +0000 (UTC) X-HE-Tag: lake70_1004bfe270d4 X-Filterd-Recvd-Size: 11842 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Sep 2020 10:26:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599560791; 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:autocrypt:autocrypt; bh=mOMtXpC9w9DNODyqnAlcSJZsWHWQ8hOHZ9+OpCpEsMo=; b=R9FP132ljNWDyEikw7JSlMgJ9SXsoU2W3vrDZfb8vC8Le+Po47moRZyrboT+x49pRjUS5X pQZ4yGL+/SKtqzgUpd35FAMkr6QRoJLcx3JeqOeP3O+F/siqPQTX88hdTzzA0qWgTAS5on yzV4/HqRzAji3Xyeg+mcTFVToBelBwE= 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-535-ocpL4LifPeKj0Evr1s394g-1; Tue, 08 Sep 2020 06:26:29 -0400 X-MC-Unique: ocpL4LifPeKj0Evr1s394g-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 86C691007467; Tue, 8 Sep 2020 10:26:26 +0000 (UTC) Received: from [10.36.115.46] (ovpn-115-46.ams2.redhat.com [10.36.115.46]) by smtp.corp.redhat.com (Postfix) with ESMTP id BA7021002D46; Tue, 8 Sep 2020 10:26:21 +0000 (UTC) Subject: Re: [PATCH v1 2/5] kernel/resource: merge_system_ram_resources() to merge resources after hotplug To: Pankaj Gupta Cc: LKML , virtualization@lists.linux-foundation.org, Linux MM , linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, Andrew Morton , Michal Hocko , Dan Williams , Jason Gunthorpe , Kees Cook , Ard Biesheuvel , Thomas Gleixner , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Julien Grall , Baoquan He , Wei Yang References: <20200821103431.13481-1-david@redhat.com> <20200821103431.13481-3-david@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63W5Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAjwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat GmbH Message-ID: <93e5b25b-ff00-b6b7-eb1e-b051ea6dcbe5@redhat.com> Date: Tue, 8 Sep 2020 12:26:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Rspamd-Queue-Id: A3DCA1814B0C1 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 Content-Transfer-Encoding: quoted-printable 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 31.08.20 11:35, Pankaj Gupta wrote: >> Some add_memory*() users add memory in small, contiguous memory blocks= . >> Examples include virtio-mem, hyper-v balloon, and the XEN balloon. >> >> This can quickly result in a lot of memory resources, whereby the actu= al >> resource boundaries are not of interest (e.g., it might be relevant fo= r >> DIMMs, exposed via /proc/iomem to user space). We really want to merge >> added resources in this scenario where possible. >> >> Let's provide an interface to trigger merging of applicable child >> resources. It will be, for example, used by virtio-mem to trigger >> merging of system ram resources it added to its resource container, bu= t >> also by XEN and Hyper-V to trigger merging of system ram resources in >> iomem_resource. >> >> Note: We really want to merge after the whole operation succeeded, not >> directly when adding a resource to the resource tree (it would break >> add_memory_resource() and require splitting resources again when the >> operation failed - e.g., due to -ENOMEM). >> >> Cc: Andrew Morton >> Cc: Michal Hocko >> Cc: Dan Williams >> Cc: Jason Gunthorpe >> Cc: Kees Cook >> Cc: Ard Biesheuvel >> Cc: Thomas Gleixner >> Cc: "K. Y. Srinivasan" >> Cc: Haiyang Zhang >> Cc: Stephen Hemminger >> Cc: Wei Liu >> Cc: Boris Ostrovsky >> Cc: Juergen Gross >> Cc: Stefano Stabellini >> Cc: Roger Pau Monn=C3=A9 >> Cc: Julien Grall >> Cc: Pankaj Gupta >> Cc: Baoquan He >> Cc: Wei Yang >> Signed-off-by: David Hildenbrand >> --- >> include/linux/ioport.h | 3 +++ >> kernel/resource.c | 52 +++++++++++++++++++++++++++++++++++++++++= + >> 2 files changed, 55 insertions(+) >> >> diff --git a/include/linux/ioport.h b/include/linux/ioport.h >> index 52a91f5fa1a36..3bb0020cd6ddc 100644 >> --- a/include/linux/ioport.h >> +++ b/include/linux/ioport.h >> @@ -251,6 +251,9 @@ extern void __release_region(struct resource *, re= source_size_t, >> extern void release_mem_region_adjustable(struct resource *, resource= _size_t, >> resource_size_t); >> #endif >> +#ifdef CONFIG_MEMORY_HOTPLUG >> +extern void merge_system_ram_resources(struct resource *res); >> +#endif >> >> /* Wrappers for managed devices */ >> struct device; >> diff --git a/kernel/resource.c b/kernel/resource.c >> index 1dcef5d53d76e..b4e0963edadd2 100644 >> --- a/kernel/resource.c >> +++ b/kernel/resource.c >> @@ -1360,6 +1360,58 @@ void release_mem_region_adjustable(struct resou= rce *parent, >> } >> #endif /* CONFIG_MEMORY_HOTREMOVE */ >> >> +#ifdef CONFIG_MEMORY_HOTPLUG >> +static bool system_ram_resources_mergeable(struct resource *r1, >> + struct resource *r2) >> +{ >> + return r1->flags =3D=3D r2->flags && r1->end + 1 =3D=3D r2->st= art && >> + r1->name =3D=3D r2->name && r1->desc =3D=3D r2->desc && >> + !r1->child && !r2->child; >> +} >> + >> +/* >> + * merge_system_ram_resources - try to merge contiguous system ram re= sources >> + * @parent: parent resource descriptor >> + * >> + * This interface is intended for memory hotplug, whereby lots of con= tiguous >> + * system ram resources are added (e.g., via add_memory*()) by a driv= er, and >> + * the actual resource boundaries are not of interest (e.g., it might= be >> + * relevant for DIMMs). Only immediate child resources that are busy = and >> + * don't have any children are considered. All applicable child resou= rces >> + * must be immutable during the request. >> + * >> + * Note: >> + * - The caller has to make sure that no pointers to resources that m= ight >> + * get merged are held anymore. Callers should only trigger merging= of child >> + * resources when they are the only one adding system ram resources= to the >> + * parent (besides during boot). >> + * - release_mem_region_adjustable() will split on demand on memory h= otunplug >> + */ >> +void merge_system_ram_resources(struct resource *parent) >> +{ >> + const unsigned long flags =3D IORESOURCE_SYSTEM_RAM | IORESOUR= CE_BUSY; >> + struct resource *cur, *next; >> + >> + write_lock(&resource_lock); >> + >> + cur =3D parent->child; >> + while (cur && cur->sibling) { >> + next =3D cur->sibling; >> + if ((cur->flags & flags) =3D=3D flags && >=20 > Maybe this can be changed to: > !(cur->flags & ~flags) That would be different I think. (cur->flags & flags) =3D=3D flags checks that all "flags" are set (additional ones might be set). !(cur->flags & ~flags) checks that no other flags besides "flags" are set (and "flags" are not required to be set). We use the same handling in find_next_iomem_res(), e.g., called via walk_system_ram_range also with IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY. Thanks for having a look! --=20 Thanks, David / dhildenb