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Tue, 17 Mar 2026 02:36:24 +0000 From: Dan Williams Date: Mon, 16 Mar 2026 19:36:22 -0700 To: "Koralahalli Channabasappa, Smita" , Dan Williams , Smita Koralahalli , , , , , CC: Ard Biesheuvel , Alison Schofield , Vishal Verma , "Ira Weiny" , Jonathan Cameron , Yazen Ghannam , Dave Jiang , Davidlohr Bueso , Matthew Wilcox , Jan Kara , "Rafael J . Wysocki" , Len Brown , Pavel Machek , Li Ming , Jeff Johnson , "Ying Huang" , Yao Xingtao , Peter Zijlstra , Greg Kroah-Hartman , Nathan Fontenot , Terry Bowman , Robert Richter , Benjamin Cheatham , Zhijian Li , Borislav Petkov , Tomasz Wolski Message-ID: <69b8be262e5ca_452b100c8@dwillia2-mobl4.notmuch> In-Reply-To: <80bab312-7945-4579-a369-380d7094bbb3@amd.com> References: <20260210064501.157591-1-Smita.KoralahalliChannabasappa@amd.com> <20260210064501.157591-9-Smita.KoralahalliChannabasappa@amd.com> <69b224bf2fd12_2132100b8@dwillia2-mobl4.notmuch> <80bab312-7945-4579-a369-380d7094bbb3@amd.com> Subject: Re: [PATCH v6 8/9] dax/hmem, cxl: Defer and resolve ownership of Soft Reserved memory ranges Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SJ0PR05CA0099.namprd05.prod.outlook.com (2603:10b6:a03:334::14) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|DM3PPF1FCD3EAF0:EE_ X-MS-Office365-Filtering-Correlation-Id: a2e91e38-149b-462f-23e3-08de83cdfb32 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016|18002099003|22082099003|56012099003; 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> + > + if (cxl_region_contains_soft_reserve(res)) > + return 0; > + > + return hmem_register_device(host, target_nid, res); > +} >=20 > +static void process_defer_work(struct work_struct *work) > +{ I think this also needs: guard(device)(&hmem_pdev->dev); if (!hmem_pdev->dev.driver) return; ...because you can remove the driver while the work is pending. > + wait_for_device_probe(); > + /* Flag lives in device.c */ > + dax_hmem_initial_probe_done =3D true; > + walk_hmem_resources(&hmem_pdev->dev, hmem_register_cxl_device); Even though nothing deletes the hmem_pdev device today, I would still keep its refcount elevated while work is pending. > +} >=20 > static int dax_hmem_platform_probe(struct platform_device *pdev) > { > + if (work_pending(&dax_hmem_work)) > + return -EBUSY; >=20 > + hmem_pdev =3D pdev; This wants to be initialized when @dax_hmem_work is initialized. Otherwise this makes it look like @hmem_pdev can change dynamically. It is a singleton. [..] > A few things I want to confirm: >=20 > 1. Patch 7 (bus.c helpers) drops entirely =E2=80=94 no register/unregiste= r API,=20 > no mutex, no typedef. Everything lives in hmem.c. >=20 > 2. enum dax_cxl_mode drops =E2=80=94 replaced by the single bool=20 > dax_hmem_initial_probe_done in device.c. >=20 > 3. dax_hmem_flush_work() exported from dax_hmem.ko so cxl.c gets the=20 > module dependency for requirement 2. Looks good to me.=