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Thu, 12 Mar 2020 13:45:20 +0000 (UTC) Received: from [10.36.118.178] (unknown [10.36.118.178]) by smtp.corp.redhat.com (Postfix) with ESMTP id 618199CA3; Thu, 12 Mar 2020 13:45:17 +0000 (UTC) Subject: Re: [PATCH v4 4/5] mm/sparse.c: add note about only VMEMMAP supporting sub-section hotplug To: Baoquan He , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com, richard.weiyang@gmail.com, dan.j.williams@intel.com References: <20200312124414.439-1-bhe@redhat.com> <20200312124414.439-5-bhe@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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <6c405f10-be9d-ca0e-3cc0-70a7bf24cbfa@redhat.com> Date: Thu, 12 Mar 2020 14:45:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200312124414.439-5-bhe@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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 12.03.20 13:44, Baoquan He wrote: > And tell check_pfn_span() gating the porper alignment and size of > hot added memory region. > > And also move the code comments from inside section_deactivate() > to being above it. The code comments are reasonable for the whole > function, and the moving makes code cleaner. > > Signed-off-by: Baoquan He > Acked-by: Michal Hocko > --- > mm/sparse.c | 38 +++++++++++++++++++++----------------- > 1 file changed, 21 insertions(+), 17 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index 117fe4554c38..f02a524e17d1 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -771,6 +771,22 @@ static bool is_subsection_map_empty(struct mem_section *ms) > } > #endif > > +/* > + * To deactivate a memory region, there are 3 cases to handle across > + * two configurations (SPARSEMEM_VMEMMAP={y,n}): > + * > + * 1. deactivation of a partial hot-added section (only possible in > + * the SPARSEMEM_VMEMMAP=y case). > + * a) section was present at memory init. > + * b) section was hot-added post memory init. > + * 2. deactivation of a complete hot-added section. > + * 3. deactivation of a complete section from memory init. > + * > + * For 1, when subsection_map does not empty we will not be freeing the > + * usage map, but still need to free the vmemmap range. > + * > + * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified > + */ > static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > struct vmem_altmap *altmap) > { > @@ -781,23 +797,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > > if (clear_subsection_map(pfn, nr_pages)) > return; > - /* > - * There are 3 cases to handle across two configurations > - * (SPARSEMEM_VMEMMAP={y,n}): > - * > - * 1/ deactivation of a partial hot-added section (only possible > - * in the SPARSEMEM_VMEMMAP=y case). > - * a/ section was present at memory init > - * b/ section was hot-added post memory init > - * 2/ deactivation of a complete hot-added section > - * 3/ deactivation of a complete section from memory init > - * > - * For 1/, when subsection_map does not empty we will not be > - * freeing the usage map, but still need to free the vmemmap > - * range. > - * > - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified > - */ > + > empty = is_subsection_map_empty(ms); > if (empty) { > unsigned long section_nr = pfn_to_section_nr(pfn); > @@ -905,6 +905,10 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, > * > * This is only intended for hotplug. > * > + * Note that only VMEMMAP supports sub-section aligned hotplug, > + * the proper alignment and size are gated by check_pfn_span(). > + * > + * > * Return: > * * 0 - On success. > * * -EEXIST - Section has been present. > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb