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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 68074C282CE for ; Tue, 9 Apr 2019 07:33:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C0EC20883 for ; Tue, 9 Apr 2019 07:33:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726630AbfDIHdZ (ORCPT ); Tue, 9 Apr 2019 03:33:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35128 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726112AbfDIHdX (ORCPT ); Tue, 9 Apr 2019 03:33:23 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 7F09C2D80F; Tue, 9 Apr 2019 07:33:21 +0000 (UTC) Received: from [10.36.117.49] (ovpn-117-49.ams2.redhat.com [10.36.117.49]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1A4EF108BEF9; Tue, 9 Apr 2019 07:33:17 +0000 (UTC) Subject: Re: [PATCH RFC 2/3] mm/memory_hotplug: Create memory block devices after arch_add_memory() To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Greg Kroah-Hartman , "Rafael J . Wysocki" , Ingo Molnar , Andrew Banman , mike.travis@hpe.com, Jonathan Cameron , Oscar Salvador , Michal Hocko , Pavel Tatashin , Wei Yang , Qian Cai , Arun KS , Mathieu Malaterre , linux-mm@kvack.org, dan.j.williams@intel.com References: <20190408101226.20976-1-david@redhat.com> <20190408101226.20976-3-david@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: Date: Tue, 9 Apr 2019 09:33:17 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190408101226.20976-3-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 09 Apr 2019 07:33:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.04.19 12:12, David Hildenbrand wrote: > Only memory added via add_memory() and friends will need memory > block devices - only memory to be used via the buddy and to be onlined/ > offlined by user space in memory block granularity. > > Move creation of memory block devices out of arch_add_memory(). Create all > devices after arch_add_memory() succeeded. We can later drop the > want_memblock parameter, because it is now effectively stale. > > Only after memory block devices have been added, memory can be onlined > by user space. This implies, that memory is not visible to user space at > all before arch_add_memory() succeeded. > > Issue 1: __add_pages() does not remove pages in case something went > wrong. If this is the case, we would now no longer create memory block > devices for such "partially added memory". So the memory would not be > usable/onlinable. Bad? Or related to issue 2 (e.g. fix __add_pages() > to remove any parts that were added in case of an error). Functions that > fail and don't clean up are not that nice. > > Issue 2: In case we can't add memory block devices, and we don't have > HOTREMOVE, we can't remove the pages via arch_remove_pages. Maybe we should > try to get rid of CONFIG_MEMORY_HOTREMOVE, so we can handle all failures > in a nice way? Or at least allow arch_remove_pages() and friends, so a > subset of CONFIG_MEMORY_HOTREMOVE. > > Signed-off-by: David Hildenbrand > --- > drivers/base/memory.c | 67 +++++++++++++++++++++++++----------------- > include/linux/memory.h | 2 +- > mm/memory_hotplug.c | 17 +++++++---- > 3 files changed, 53 insertions(+), 33 deletions(-) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index d9ebb89816f7..847b33061e2e 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -701,44 +701,57 @@ static int add_memory_block(int base_section_nr) > return 0; > } > > -/* > - * need an interface for the VM to add new memory regions, > - * but without onlining it. > - */ > -int hotplug_memory_register(int nid, struct mem_section *section) > +static void unregister_memory(struct memory_block *memory) > { > - int ret = 0; > + BUG_ON(memory->dev.bus != &memory_subsys); > + > + /* drop the ref. we got via find_memory_block() */ > + put_device(&memory->dev); > + device_unregister(&memory->dev); > +} > + > +int hotplug_memory_register(unsigned long start, unsigned long size) > +{ > + unsigned long block_nr_pages = memory_block_size_bytes() >> PAGE_SHIFT; > + unsigned long start_pfn = PFN_DOWN(start); > + unsigned long end_pfn = start_pfn + (size >> PAGE_SHIFT); > + unsigned long pfn; > struct memory_block *mem; > + int ret = 0; > > - mutex_lock(&mem_sysfs_mutex); > + BUG_ON(!IS_ALIGNED(start, memory_block_size_bytes())); > + BUG_ON(!IS_ALIGNED(size, memory_block_size_bytes())); > > - mem = find_memory_block(section); > - if (mem) { > - mem->section_count++; > - put_device(&mem->dev); > - } else { > - ret = init_memory_block(&mem, section, MEM_OFFLINE); > + mutex_lock(&mem_sysfs_mutex); > + for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) { > + mem = find_memory_block(__pfn_to_section(pfn)); > + if (mem) { > + WARN_ON_ONCE(false); > + put_device(&mem->dev); > + continue; > + } > + ret = init_memory_block(&mem, __pfn_to_section(pfn), > + MEM_OFFLINE); > if (ret) > - goto out; > - mem->section_count++; > + break; > + mem->section_count = memory_block_size_bytes() / > + MIN_MEMORY_BLOCK_SIZE; > + } > + if (ret) { > + end_pfn = pfn; > + for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) { > + mem = find_memory_block(__pfn_to_section(pfn)); > + if (!mem) > + continue; > + mem->section_count = 0; > + unregister_memory(mem); > + } > } > - > -out: > mutex_unlock(&mem_sysfs_mutex); > return ret; > } > > #ifdef CONFIG_MEMORY_HOTREMOVE > -static void > -unregister_memory(struct memory_block *memory) > -{ > - BUG_ON(memory->dev.bus != &memory_subsys); > - > - /* drop the ref. we got in remove_memory_section() */ > - put_device(&memory->dev); > - device_unregister(&memory->dev); > -} > - > static int remove_memory_section(struct mem_section *section) > { > struct memory_block *mem; > diff --git a/include/linux/memory.h b/include/linux/memory.h > index a6ddefc60517..e275dc775834 100644 > --- a/include/linux/memory.h > +++ b/include/linux/memory.h > @@ -111,7 +111,7 @@ extern int register_memory_notifier(struct notifier_block *nb); > extern void unregister_memory_notifier(struct notifier_block *nb); > extern int register_memory_isolate_notifier(struct notifier_block *nb); > extern void unregister_memory_isolate_notifier(struct notifier_block *nb); > -int hotplug_memory_register(int nid, struct mem_section *section); > +int hotplug_memory_register(unsigned long start, unsigned long size); > #ifdef CONFIG_MEMORY_HOTREMOVE > extern int unregister_memory_section(struct mem_section *); > #endif > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 680dcc67f9d5..13ee0a26e034 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -260,11 +260,7 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn, > ret = sparse_add_one_section(nid, phys_start_pfn, altmap); > if (ret < 0) > return ret; > - > - if (!want_memblock) > - return 0; > - > - return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn)); > + return 0; > } > > /* > @@ -1125,6 +1121,17 @@ int __ref add_memory_resource(int nid, struct resource *res) > if (ret < 0) > goto error; > > + /* create memory block devices after memory was added */ > + ret = hotplug_memory_register(start, size); > +#ifdef CONFIG_MEMORY_HOTREMOVE > + if (ret) { > + arch_remove_memory(nid, start, size, NULL); > + goto error; > + } > +#else > + WARN_ON(ret); > +#endif > + > if (new_node) { > /* If sysfs file of new node can't be created, cpu on the node > * can't be hot-added. There is no rollback way now. > FWIW, I think we should first try to make sure arch_remove_memory() cannot fail / will not ignore errors if possible. There are still some things in there that need more re-factoring first. -- Thanks, David / dhildenb