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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] mm/compaction: stop recording free page order in page->private Date: Mon, 29 Jun 2026 11:03:38 -0400 X-Mailer: MailMate (2.0r6290) Message-ID: <4CD1FE9D-3860-4A55-ABCE-13C97DB205BC@nvidia.com> In-Reply-To: <220774cb-ba5b-4a12-a649-955c83bfc704@kernel.org> References: <20260628-keep-subpage-private-zero-at-free-v1-0-f4ce3930d10f@nvidia.com> <20260628-keep-subpage-private-zero-at-free-v1-1-f4ce3930d10f@nvidia.com> <220774cb-ba5b-4a12-a649-955c83bfc704@kernel.org> Content-Type: text/plain X-ClientProxiedBy: BL1PR13CA0208.namprd13.prod.outlook.com (2603:10b6:208:2be::33) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|DS0PR12MB999103:EE_ X-MS-Office365-Filtering-Correlation-Id: 73201922-ad59-436b-4f00-08ded5ef9a7a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|7416014|376014|366016|1800799024|22082099003|18002099003|56012099006|6133799003|11063799006|4143699003; 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And there is no code using the stored order. Stop doing >> that. > > Ah, great observation. Cool. > >> It also prepares for an upcoming change that ensures subpage->private is >> zero at page free time and the removal of set_page_private(0) from >> prep_compound_tail(). In alloc_contig_frozen_range_noprof(), >> isolate_freepages_range() is used to grab free pages from buddy allocator >> and it leaves the aforementioned page->private set until >> either split_free_frozen_pages() or prep_new_page() is called. >> That >> triggers the upcoming subpage->private nonzero check along once >> set_page_private(0) is removed from prep_compound_tail(), which is called >> via prep_new_page(). > > I'm not sure it needs to be said here (or in such detail?) Will move it to the cover letter. > >> Signed-off-by: Zi Yan > > Reviewed-by: Vlastimil Babka (SUSE) Thanks. Best Regards, Yan, Zi