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b=kXIiy4cQtJZzc4lD9BdXL/n0a1g+am0DgjtGgvNg1lD6RST5L3W25MAPBSLwM9RNv POPNgzX+gPz3QofT8xly854/Yq/CkSODtg1s5b+GhDuvvXHc4p66fWvgwbzvlz7wME StKb3zZDbPhsHKYfMt/SEp+CKj7F3Zd5rQa5Thhc= Date: Thu, 19 Mar 2026 20:13:07 -0700 From: Andrew Morton To: Yuan Liu Cc: David Hildenbrand , Oscar Salvador , Mike Rapoport , Wei Yang , linux-mm@kvack.org, Yong Hu , Nanhai Zou , Tim Chen , Qiuxu Zhuo , Yu C Chen , Pan Deng , Tianyou Li , Chen Zhang , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/memory hotplug/unplug: Optimize zone contiguous check when changing pfn range Message-Id: <20260319201307.da2257e27949adace34460cf@linux-foundation.org> In-Reply-To: <20260319095622.1130380-1-yuan1.liu@intel.com> References: <20260319095622.1130380-1-yuan1.liu@intel.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: keinzy9t5pophwgguqc5wjf3n48y189s X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 282DA1A0002 X-HE-Tag: 1773976389-374693 X-HE-Meta: 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 bLCuQTXK Rciq6d9q4gQuPAOJIR/yZ+DTrLKIgYPUKY1NjTcdV3vWPOw9l2WHFrLNxEQDbGlxI1Hbhd0513NShY3GuKvhvC3tTG4rZ2ZwYuVY2QO4VnrC9VljGGu6mEeAzdlWd1cR6dxg+7WMK+2euyyZv7/DAH8atS3gs1lkKThfv9p9RzZVri/70mqa2iiqs2jQk0S0hwxSiWy+Blkv2AZnuy78lN6I2pZBDGhQcoQYBMNCM88CM/YW1bv0FxqOWaj+nEEAO30grOnZDengAc8OHFrDH4fYPZvPBS4u/8G3NoRVd+3fcdzYaV9droY6UhKTT8F50/YVCY/KrZOE4EzAJhscvePIEh/G3PhinyfY0wd9C0tIkonm4u+q5Xil5ubC8javsz7k6Qd0hbg4s6AjTl+lKUe1RazJVAj24O3DzvY0GtRAgtFM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 19 Mar 2026 05:56:22 -0400 Yuan Liu wrote: > When invoke move_pfn_range_to_zone or remove_pfn_range_from_zone, it will > update the zone->contiguous by checking the new zone's pfn range from the > beginning to the end, regardless the previous state of the old zone. When > the zone's pfn range is large, the cost of traversing the pfn range to > update the zone->contiguous could be significant. > > Add a new zone's pages_with_memmap member, it is pages within the zone that > have an online memmap. It includes present pages and memory holes that have > a memmap. When spanned_pages == pages_with_online_memmap, pfn_to_page() can > be performed without further checks on any pfn within the zone span. AI review asks questions: https://sashiko.dev/#/patchset/20260319095622.1130380-1-yuan1.liu%40intel.com