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Sun, 15 Aug 2021 20:40:29 +0000 Subject: Re: [PATCH v6 02/13] mm: remove extra ZONE_DEVICE struct page refcount To: Christoph Hellwig , Alex Sierra CC: , , , , , , , , , References: <20210813063150.2938-1-alex.sierra@amd.com> <20210813063150.2938-3-alex.sierra@amd.com> <20210815153713.GA32384@lst.de> From: John Hubbard Message-ID: <387d5f85-3d15-9a9e-2382-6ce3c14bc6d5@nvidia.com> Date: Sun, 15 Aug 2021 13:40:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210815153713.GA32384@lst.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [172.20.187.6] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7afafabb-95a6-41a5-703e-08d9602cec5e X-MS-TrafficTypeDiagnostic: CH2PR12MB3701: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:3383; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Aug 2021 20:40:30.9026 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7afafabb-95a6-41a5-703e-08d9602cec5e X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT065.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB3701 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 8/15/21 8:37 AM, Christoph Hellwig wrote: >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 8ae31622deef..d48a1f0889d1 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -1218,7 +1218,7 @@ __maybe_unused struct page *try_grab_compound_head(struct page *page, int refs, >> static inline __must_check bool try_get_page(struct page *page) >> { >> page = compound_head(page); >> - if (WARN_ON_ONCE(page_ref_count(page) <= 0)) >> + if (WARN_ON_ONCE(page_ref_count(page) < (int)!is_zone_device_page(page))) > > Please avoid the overly long line. In fact I'd be tempted to just not > bother here and keep the old, more lose check. Especially given that > John has a patch ready that removes try_get_page entirely. > Yes. Andrew has accepted it into mmotm. Ralph's patch here was written well before my cleanup that removed try_grab_page() [1]. But now that we're here, if you drop this hunk then it will make merging easier, I think. [1] https://lore.kernel.org/r/20210813044133.1536842-4-jhubbard@nvidia.com thanks, -- John Hubbard NVIDIA