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b=H7hu6XAQlGaj6U8q7BwK835aeItmd4QjmvzClJs2EbZmpwE9+VOsR0G0K14C3ihpj cUFc0mmaAqkyHcaYNiYz4Ymm6Mh1MxFR/CCjlB95TtapACDHNu7OwmZecjZvt9Jkrs RY9jHQc81ffHrRsLZZgjJ0Vc4rORC4DAcmhBCkYK7RG8KmVYZRIXiTnd9pRIajwxYu Yi8oMek2rvWBsM2DNv1++FGUe6Z5Z+R7i38L5wyvGAnhfpwQMw22/ysu/CJQu+2kf6 KN2tFN4NGRC0RVaC6HpgJ1cQ4RdgquTZBOCzQGhSWsXrCBHc+gTPjiWmgRGK2xFP99 cloYBj18z91UA== Date: Wed, 19 Aug 2026 17:56:04 +0300 From: Mike Rapoport To: Yuan Liu Cc: David Hildenbrand , Oscar Salvador , Wei Yang , linux-mm@kvack.org, Nanhai Zou , Chen Zhang , Jason Zeng , Chen Yu , Pan Deng , Tianyou Li , linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 2/2] mm/memory_hotplug: optimize zone contiguous check when changing pfn range Message-ID: References: <20260818085702.3395529-1-yuan1.liu@intel.com> <20260818085702.3395529-3-yuan1.liu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260818085702.3395529-3-yuan1.liu@intel.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E22932000B X-Stat-Signature: jwmbx3hftcnckqasrmcg1qx4xhpkkgb7 X-Rspam-User: X-HE-Tag: 1787151372-230516 X-HE-Meta: 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 voklDVUb 78wAN72UB2Dp2p1gXlhRj8xwUiiG9V8vAhOis8JxMJoxzx+885qkyw95kAop7mqQlcx5HRKoOn2tjuph6XVyNzkggsHClzOGn0X2JEudtjuXGiy9j4CVKzQ8dp+/yMfd8qM/bBJXHFm7uMqGoylKOy16PI5Dv/oVjP6d9QUGb8GQ7KCv5hxrm59l1oxAFClyRKcVW9VKiSSaLI7EuxF07/Cf7DLebKJNHlUh+ctDxCG2wmHw9PfhHSIlT3zHu6zbSy172VsipayPh80UHVVYo6whq9xxaf2LAJQWMWHyNIGtrqGWH1TomizhwKdYRydJuiP+G3PouxQ733PfUfRtwdB7hrEdolkdOO9nAtrYEJ9o4IYK6Mz4nJrGKvu1GMJtOkDkC Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 18, 2026 at 04:57:02AM -0400, Yuan Liu wrote: > When move_pfn_range_to_zone() or remove_pfn_range_from_zone() updates a > zone, set_zone_contiguous() rescans the entire zone pageblock-by-pageblock > to rebuild zone->contiguous. For large zones this is a significant cost > during memory hotplug and hot-unplug. > > Add a new zone member, pages_with_online_memmap, that tracks the > number of pages within the zone span that have an online memory map, > including present pages and memory holes whose memory map has been > initialized and for which pfn_to_online_page() succeeds. > > For early boot memory, pages_with_online_memmap is calculated in > memmap_init_zone_range(). PFNs initialized by memmap_init_range() are > included in pages_with_online_memmap, and hole PFNs for which > pfn_to_online_page() succeeds are also counted in > init_unavailable_range(). In what scenario it is possible that pfn_to_online_page() would fail at that point? -- Sincerely yours, Mike.