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[209.132.183.28]) by mx.google.com with ESMTPS id c22si18042068qkm.22.2019.07.19.01.48.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 01:48:23 -0700 (PDT) Received-SPF: pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com 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 8A5823B71F; Fri, 19 Jul 2019 08:48:22 +0000 (UTC) Received: from [10.36.117.221] (ovpn-117-221.ams2.redhat.com [10.36.117.221]) by smtp.corp.redhat.com (Postfix) with ESMTP id A4C6D10190BD; Fri, 19 Jul 2019 08:48:20 +0000 (UTC) Subject: Re: [PATCH v1] drivers/base/node.c: Simplify unregister_memory_block_under_nodes() To: Michal Hocko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Stephen Rothwell , Pavel Tatashin , Oscar Salvador References: <20190718142239.7205-1-david@redhat.com> <20190719084239.GO30461@dhcp22.suse.cz> 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: <4eefc51b-4cda-0ede-72d1-0f1c33d87ce8@redhat.com> Date: Fri, 19 Jul 2019 10:48:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190719084239.GO30461@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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]); Fri, 19 Jul 2019 08:48:22 +0000 (UTC) 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 19.07.19 10:42, Michal Hocko wrote: > On Thu 18-07-19 16:22:39, David Hildenbrand wrote: >> We don't allow to offline memory block devices that belong to multiple >> numa nodes. Therefore, such devices can never get removed. It is >> sufficient to process a single node when removing the memory block. >> >> Remember for each memory block if it belongs to no, a single, or mixed >> nodes, so we can use that information to skip unregistering or print a >> warning (essentially a safety net to catch BUGs). > > I do not really like NUMA_NO_NODE - 1 thing. This is yet another invalid > node that is magic. Why should we even care? In other words why is this > patch an improvement? I mean we can of course go ahead and drop the "NUMA_NO_NODE - 1" thingy from the patch. A memory block with multiple nodes would (as of now) only indicate one of the nodes. Then there is simply no way to WARN_ON_ONCE() in case unexpected things would happen. (I mean it really shouldn't happen or we have a BUG somewhere else) Alternative: Add "bool mixed_nids;" to "struct memory block". > >> Cc: Greg Kroah-Hartman >> Cc: "Rafael J. Wysocki" >> Cc: Andrew Morton >> Cc: David Hildenbrand >> Cc: Stephen Rothwell >> Cc: Pavel Tatashin >> Cc: Michal Hocko >> Cc: Oscar Salvador >> Signed-off-by: David Hildenbrand >> --- >> drivers/base/memory.c | 1 + >> drivers/base/node.c | 40 ++++++++++++++++------------------------ >> include/linux/memory.h | 4 +++- >> 3 files changed, 20 insertions(+), 25 deletions(-) >> >> diff --git a/drivers/base/memory.c b/drivers/base/memory.c >> index 20c39d1bcef8..154d5d4a0779 100644 >> --- a/drivers/base/memory.c >> +++ b/drivers/base/memory.c >> @@ -674,6 +674,7 @@ static int init_memory_block(struct memory_block **memory, >> mem->state = state; >> start_pfn = section_nr_to_pfn(mem->start_section_nr); >> mem->phys_device = arch_get_memory_phys_device(start_pfn); >> + mem->nid = NUMA_NO_NODE; >> >> ret = register_memory(mem); >> >> diff --git a/drivers/base/node.c b/drivers/base/node.c >> index 75b7e6f6535b..29d27b8d5fda 100644 >> --- a/drivers/base/node.c >> +++ b/drivers/base/node.c >> @@ -759,8 +759,6 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk, >> int ret, nid = *(int *)arg; >> unsigned long pfn, sect_start_pfn, sect_end_pfn; >> >> - mem_blk->nid = nid; >> - >> sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); >> sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr); >> sect_end_pfn += PAGES_PER_SECTION - 1; >> @@ -789,6 +787,13 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk, >> if (page_nid != nid) >> continue; >> } >> + >> + /* this memory block spans this node */ >> + if (mem_blk->nid == NUMA_NO_NODE) >> + mem_blk->nid = nid; >> + else >> + mem_blk->nid = NUMA_NO_NODE - 1; >> + >> ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, >> &mem_blk->dev.kobj, >> kobject_name(&mem_blk->dev.kobj)); >> @@ -804,32 +809,19 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk, >> } >> >> /* >> - * Unregister memory block device under all nodes that it spans. >> - * Has to be called with mem_sysfs_mutex held (due to unlinked_nodes). >> + * Unregister a memory block device under the node it spans. Memory blocks >> + * with multiple nodes cannot be offlined and therefore also never be removed. >> */ >> void unregister_memory_block_under_nodes(struct memory_block *mem_blk) >> { >> - unsigned long pfn, sect_start_pfn, sect_end_pfn; >> - static nodemask_t unlinked_nodes; >> - >> - nodes_clear(unlinked_nodes); >> - sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); >> - sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr); >> - for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) { >> - int nid; >> + if (mem_blk->nid == NUMA_NO_NODE || >> + WARN_ON_ONCE(mem_blk->nid == NUMA_NO_NODE - 1)) >> + return; >> >> - nid = get_nid_for_pfn(pfn); >> - if (nid < 0) >> - continue; >> - if (!node_online(nid)) >> - continue; >> - if (node_test_and_set(nid, unlinked_nodes)) >> - continue; >> - sysfs_remove_link(&node_devices[nid]->dev.kobj, >> - kobject_name(&mem_blk->dev.kobj)); >> - sysfs_remove_link(&mem_blk->dev.kobj, >> - kobject_name(&node_devices[nid]->dev.kobj)); >> - } >> + sysfs_remove_link(&node_devices[mem_blk->nid]->dev.kobj, >> + kobject_name(&mem_blk->dev.kobj)); >> + sysfs_remove_link(&mem_blk->dev.kobj, >> + kobject_name(&node_devices[mem_blk->nid]->dev.kobj)); >> } >> >> int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn) >> diff --git a/include/linux/memory.h b/include/linux/memory.h >> index 02e633f3ede0..c91af10d5fb4 100644 >> --- a/include/linux/memory.h >> +++ b/include/linux/memory.h >> @@ -33,7 +33,9 @@ struct memory_block { >> void *hw; /* optional pointer to fw/hw data */ >> int (*phys_callback)(struct memory_block *); >> struct device dev; >> - int nid; /* NID for this memory block */ >> + int nid; /* NID for this memory block. >> + - NUMA_NO_NODE: uninitialized >> + - NUMA_NO_NODE - 1: mixed nodes */ >> }; >> >> int arch_get_memory_phys_device(unsigned long start_pfn); >> -- >> 2.21.0 > -- Thanks, David / dhildenb