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b=bv7EzWDiendze/cP586ru5zBpHpfCly8MOX3VxeiW381Thyq5+xgeBLPmDNR9+jdi JAOrL8xYk19kWk4srpq3Qin0GmbD6FLxg0sC+mQRf0F7UQFseVZPC0Kn0XMrkua7p+ jyuqkpfOWUKjHFO3qv4JfoGJvnaWs4NCNGAKZ0hiUqCB3t1DRiRIqviwua3mzILUne 6zqF76LQM8geG+0JjCw2KugvN9IszV9WTp3MHfeCZ0BlNIo4dsPQ4jBlrtL77nPg1f IsjOZGxkgXZ9b56jYnxu1sdNaARVf03RaHZ0K7DeEaM07nKsgcRfI00Yes63M9BMnj y2Q0UeF/w8xCQ== Message-ID: <00d07c59-e573-40b6-a096-266ef14545b9@kernel.org> Date: Fri, 6 Feb 2026 14:03:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/memory hotplug: Fix zone->contiguous always false when hotplug To: Tianyou Li , Oscar Salvador , Mike Rapoport , Wei Yang , Michal Hocko Cc: linux-mm@kvack.org, Yong Hu , Nanhai Zou , Yuan Liu , Tim Chen , Qiuxu Zhuo , Yu C Chen , Pan Deng , Chen Zhang , linux-kernel@vger.kernel.org References: <20260130160938.2671462-1-tianyou.li@intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260130160938.2671462-1-tianyou.li@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Stat-Signature: c68jfnxj8bknt79mim74fmbz5m6eaw3h X-Rspamd-Queue-Id: B65501C0005 X-Rspam-User: X-HE-Tag: 1770383025-492879 X-HE-Meta: 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 zOFgRcvQ VlMYmjeTHIJlKWKAFsMGcxxjYXkmpEcyHYEA4Liei9PGfO9z669igzAX+7BPeOlN1xD5GZYow0y1XfQ6rVCokNeuLXBaNu/sbcKviP4x4s4FDK73NpWWMFHQJ860qkr0yZ32rMBriobB6mLZv0Iur6FPt/O6k/Boaq5pUrxPq2KgL1xOGlJjAmba5eoHsYOrFYBOFPul0ez0nt8MYR8NxVn0oPHunX0eX3mFqT1Y+xVWTTc9dCQcZJjtqxeKKyMWz8/VxsdCjNrZnvkRmIl/zAZjitMlFRZisq8xb4ZvgiRHtiod26R5bhnt3FiDOfoifu+WYEbQPQXvTsdCz60duIZSyY/4fLoAELtq5LSY/6cFswbRDr+kwmWXgFevKHnSZL9AcZSqC9Dpp61CE4W7i907Xc1qScAR3hof6DmPBCZUKzwqxwlE6mhrxyg== 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: List-Subscribe: List-Unsubscribe: On 1/30/26 17:09, Tianyou Li wrote: > From: Yuan Liu Nit: subject should start with "mm/memory_hotplug:" > > set_zone_contiguous() uses __pageblock_pfn_to_page() to detect > pageblocks that either do not exist (hole) or that do not belong > to the same zone. > > __pageblock_pfn_to_page(), however, relies on pfn_to_online_page(), > effectively always returning NULL for memory ranges that were not > onlined yet. So when called on a range-to-be-onlined, it indicates > a memory hole to set_zone_contiguous(). > > Consequently, the set_zone_contiguous() call in move_pfn_range_to_zone(), > which happens early during memory onlining, will never detect a > zone as being contiguous. Bad: the fast path relies on the zone > contiguous state may skipped. > > To fix the issue, move the set_zone_contiguous() call to a later > stage in memory onlining, where pfn_to_online_page() will succeed: > after we mark the memory sections to be online. > > Fixes: 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes") > Cc: Michal Hocko > Cc: stable@vger.kernel.org > Reviewed-by: Nanhai Zou > Signed-off-by: Yuan Liu > Signed-off-by: Tianyou Li How was Yuan Liu involved? If he is a co-author there is a Co-developed-by: Yuan Liu missing. Likely there is no resend required if you tell Andrew what to do, so he can just fixup when applying. Acked-by: David Hildenbrand (Arm) -- Cheers, David