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[2003:cb:c70e:d000:4622:73e7:6184:8f0d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a1c8a6e19sm6705451f8f.100.2024.12.21.07.30.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 21 Dec 2024 07:30:23 -0800 (PST) Message-ID: <5e958aaa-b1ac-4512-a592-0e1612032861@redhat.com> Date: Sat, 21 Dec 2024 16:30:21 +0100 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm: add build-time option for hotplug memory default online type To: Gregory Price , linux-mm@kvack.org Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, kernel-team@meta.com, corbet@lwn.net, osalvador@suse.de, akpm@linux-foundation.org, chenhuacai@kernel.org, kernel@xen0n.name, gregkh@linuxfoundation.org, rafael@kernel.org References: <20241220210709.300066-1-gourry@gourry.net> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW 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/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/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 In-Reply-To: <20241220210709.300066-1-gourry@gourry.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > > -config MEMORY_HOTPLUG_DEFAULT_ONLINE > - bool "Online the newly added memory blocks by default" > - depends on MEMORY_HOTPLUG > +choice > + prompt "Memory Hotplug Default Online Type" > + default MHP_DEFAULT_ONLINE_TYPE_OFFLINE > help > + Default memory type for driver managed hotplug memory. We should call it "hotplugged memory" consistently, which it is from a pure core-mm perspective ("add memory"). "Driver managed" reminds too much about add_memory_driver_managed(), which is only one case. Maybe just drop the "e.g., page tables" from the examples below. > + > This option sets the default policy setting for memory hotplug > onlining policy (/sys/devices/system/memory/auto_online_blocks) which > determines what happens to newly added memory regions. Policy setting > can always be changed at runtime. > + > + The default is 'offline'. > + > + Select offline to defer onlining to drivers and user policy. > + Select auto to let the kernel choose what zones to utilize. > + Select online_kernel to generally allow kernel usage of this memory. > + Select online_movable to generally disallow kernel usage of this memory. > + > + Example kernel usage would be page structs and page tables. > + > See Documentation/admin-guide/mm/memory-hotplug.rst for more information. > > - Say Y here if you want all hot-plugged memory blocks to appear in > - 'online' state by default. > - Say N here if you want the default policy to keep all hot-plugged > - memory blocks in 'offline' state. > +config MHP_DEFAULT_ONLINE_TYPE_OFFLINE > + bool "offline" > + help > + Driver managed memory will not be onlined by default. "Hotplugged memory" > + Choose this for systems with drivers and user policy that> + handle onlining of hotplug memory policy. > +> +config MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO > + bool "auto" > + help > + Select this if you want the kernel to automatically online > + memory into the zone it thinks is reasonable. This memory hotplugged memory > + may be utilized for kernel data (e.g. page tables). > + > +config MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL > + bool "kernel" > + help > + Select this if you want the kernel to automatically online > + hotplug memory into a zone capable of being used for kernel > + data (e.g. page tables). This typically means ZONE_NORMAL. > + > +config MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE > + bool "movable" > + help > + Select this if you want the kernel to automatically online > + hotplug memory into ZONE_MOVABLE. This memory will generally > + not be utilized for kernel data (e.g. page tables). > + > + This should only be used when the admin knows sufficient > + ZONE_NORMAL memory is available to describe hotplug memory, > + otherwise hotplug memory may fail to online. For example, > + sufficient kernel-capable memory (ZONE_NORMAL) must be > + available to allocate page structs to describe ZONE_MOVABLE. > + > +endchoice > > config MEMORY_HOTREMOVE > bool "Allow for memory hot remove" > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 3b6f93962481..e3655f07dd6e 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -219,11 +219,30 @@ void put_online_mems(void) > > bool movable_node_enabled = false; > > -#ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE > -int mhp_default_online_type = MMOP_OFFLINE; > -#else > -int mhp_default_online_type = MMOP_ONLINE; > -#endif > +static int mhp_default_online_type = -1; > +int mhp_get_default_online_type(void) > +{ > + if (mhp_default_online_type >= 0) > + return mhp_default_online_type; > + > + if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE)) > + mhp_default_online_type = MMOP_OFFLINE; > + else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO)) > + mhp_default_online_type = MMOP_ONLINE; > + else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL)) > + mhp_default_online_type = MMOP_ONLINE_KERNEL; > + else if (IS_ENABLED(CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE)) > + mhp_default_online_type = MMOP_ONLINE_MOVABLE; > + else > + mhp_default_online_type = MMOP_OFFLINE; What would be nice is if we could use the symbols from Kconfig, to then only do mhp_default_online_type = CONFIG_MHP_DEFAULT_ONLINE_TYPE; But as far as I know, that's not possible. Thanks! Acked-by: David Hildenbrand -- Cheers, David / dhildenb