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b=sPTXoRAUZy7+5HMmKMBg7oSDx64qfa2bYEEcRd1o/4Rk20ewPDlkj8ugKo6nycHZv LG6LJWVSVw8nme8XzLP5CNSpb/oDtkNZvc7+JBFo2DSXs7d8gdkkhGK9+UZxOb2SW9 IwcJavRooCZYjp4ma7NgJozCm0ultg3bLazNEc5LXy9otDU9MGBCdMh1B64FUO8dqM UIh4fdAuoO9azteRUa7wIMQHR0OEYfKFFg7USkJBD3ZQpFUB5JPAsXvEO6i+WJWwCS 6jP15uCkjKqLjlpVwHJVQ6xFWw1lwN9Eiw+/QSa8p+QLmdAZJBBFfjq8NMqVK6tTyU GDPIqWXYSdYhw== Date: Tue, 27 Jan 2026 09:10:16 +0200 From: Mike Rapoport To: "Li, Tianyou" Cc: David Hildenbrand , Oscar Salvador , Wei Yang , Michal Hocko , 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 Subject: Re: [PATCH v8 3/3] mm/memory hotplug/unplug: Optimize zone->contiguous update when changes pfn range Message-ID: References: <20260120143346.1427837-1-tianyou.li@intel.com> <20260120143346.1427837-4-tianyou.li@intel.com> <0f679956-fd29-4165-a136-18f68e517fb5@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0f679956-fd29-4165-a136-18f68e517fb5@intel.com> X-Rspamd-Server: rspam12 X-Stat-Signature: 6txmyic7ckbw969cnexh6aa9ysied6e8 X-Rspamd-Queue-Id: 176B0100006 X-Rspam-User: X-HE-Tag: 1769497825-894962 X-HE-Meta: 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 FipTHGbm CEVHSnDJdypHsyyLLdiLPpexKodPi5PWTQ/yhXPeDbUStABr/08ImKi6HXyMzr5qpFDurq5vrWUhaBJirOxUqiOA24/XCqPWQjKpUSHRwhYj03wfi+scQ4VeArH2/9zGXRVeRhaLdgESon8JKScpT2nGnsIZUz6/8pSTON/zqC3ggpy9tnzhz/jL0I86F2Nh1yqypI52EO4TXjuWwApv8WEf2l9fh62gBaEe3D3OJp+VhzQUOVDcnLqvsj/b29eJG+uDHoInfLOz1jM0y7jw4hUKjippc7WqU3nUWsdNSDTFPn5guS8/Tk5VRY5SL83czP5VzBkqyDTizsakRrL5d9iZAdHxhk0gbvwS7 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: Hi, On Sat, Jan 24, 2026 at 08:43:51PM +0800, Li, Tianyou wrote: > On 1/22/2026 7:43 PM, Mike Rapoport wrote: > > > > +int online_memory_block_pages(unsigned long start_pfn, unsigned long nr_pages, > > > + unsigned long nr_vmemmap_pages, struct zone *zone, > > > + struct memory_group *group) > > > { > > > + const bool contiguous = zone->contiguous; > > > + enum zone_contig_state new_contiguous_state; > > > int ret; > > > + /* > > > + * Calculate the new zone contig state before move_pfn_range_to_zone() > > > + * sets the zone temporarily to non-contiguous. > > > + */ > > > + new_contiguous_state = zone_contig_state_after_growing(zone, start_pfn, > > > + nr_pages); > > > + > > > if (nr_vmemmap_pages) { > > > ret = mhp_init_memmap_on_memory(start_pfn, nr_vmemmap_pages, zone); > > > if (ret) > > > - return ret; > > > + goto restore_zone_contig; > > But zone_contig_state_after_growing() does not change zone->contiguous. Why > > do we need to save and restore it? > > Move_pfn_range_to_zone() will clear the zone contiguous state and it was > invoked by online_pages(). If error occurs after > move_pfn_range_to_zone() called like in online_pages(), I think we'd better > to restore the original value if previous zone contiguous state is true. But after move_pfn_range_to_zone() the added pages are still offline, so I think the zone remains contiguous and the call to clear_zone_contiguous(zone) should not be there. BTW, as we have set_zone_contiguous(ZONE_CONTIG_NO) I think we can use it instead if clear_zone_contiguous() and remove the latter. -- Sincerely yours, Mike.