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Harding" , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 0/4] mm: Use slab_list list_head instead of lru Thread-Topic: [PATCH 0/4] mm: Use slab_list list_head instead of lru Thread-Index: AQHU16bt6o0Uju0YQ0mKx1ZofK0W1KYGcySAgACefICAABJggA== Date: Tue, 12 Mar 2019 00:22:23 +0000 Message-ID: <20190312002217.GA31718@tower.DHCP.thefacebook.com> References: <20190311010744.5862-1-tobin@kernel.org> <20190311204919.GA20002@tower.DHCP.thefacebook.com> <20190311231633.GF19508@bombadil.infradead.org> In-Reply-To: <20190311231633.GF19508@bombadil.infradead.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: MWHPR12CA0051.namprd12.prod.outlook.com (2603:10b6:300:103::13) To BYAPR15MB2631.namprd15.prod.outlook.com (2603:10b6:a03:152::24) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [2620:10d:c090:200::1:b487] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 99105728-2c96-4369-0985-08d6a680cc2b x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600127)(711020)(4605104)(2017052603328)(7153060)(7193020);SRVR:BYAPR15MB2277; x-ms-traffictypediagnostic: BYAPR15MB2277: x-microsoft-exchange-diagnostics: 1;BYAPR15MB2277;20:j2HEAzGPQrT12A5YakqCjunL279UwwJ2XjS9VQcb0yDsReL20QOPljntn9jVIBhFN3QhA1W5x7BsI5q6nv9lNb8yuV6cL/yfMBZcNzHvBupLRAanCywaYW9+TeUmYNdjWC7IRw7kXRM3Pvf11VgLpz20edHOd3DtWSxIFKLGswI= x-microsoft-antispam-prvs: x-forefront-prvs: 09749A275C x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(396003)(376002)(366004)(136003)(346002)(189003)(199004)(6506007)(105586002)(76176011)(386003)(8936002)(316002)(6246003)(99286004)(4326008)(8676002)(14454004)(25786009)(54906003)(478600001)(52116002)(33656002)(106356001)(86362001)(6486002)(229853002)(256004)(81156014)(6916009)(81166006)(2906002)(53936002)(5660300002)(6436002)(9686003)(486006)(446003)(476003)(71200400001)(71190400001)(6512007)(46003)(102836004)(7736002)(97736004)(6116002)(305945005)(68736007)(1076003)(186003)(11346002);DIR:OUT;SFP:1102;SCL:1;SRVR:BYAPR15MB2277;H:BYAPR15MB2631.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: FDh92YlZhSWl4jGk6TDt7nuSmVStS1n3fSuB75VwysyYmEiCP/CndcMBMn37ptykSxzFFa7Do4fa3m9XjUrV3542EKEbUppSaei8CkOmYJEN8hGVId8QqBOCM+7UD5qMem9xuw2bRu6MLdnjGNmGkP9E+m4eg35ux3YRC4ZNIDY45/kNnG0V+2jJr6eZgyklIseI5DZDEGNKEb2w+AJnSujmZeJHOLvBzYzTt2vDfOFfLV1EYvlIR+y4etXrjszX/L541m4PigyHMbfVMP11aMlsHqi0RWwiHcY+4ep5SzFDfM+F2j4YJDxhSLzdvZlIU/zxhIft9J6MHMdj8vvDftN/3RbWKOUNsSkUR6BWG6rv4JzxgsQGi2qGuErlNrdBQjc53C0MxSqBX4y5wpkOYzE1in7ExI1ECLZn09G0x8I= Content-Type: text/plain; charset="us-ascii" Content-ID: <1C0F0C1D7F614A47853BB28A21E359F7@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 99105728-2c96-4369-0985-08d6a680cc2b X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Mar 2019 00:22:23.3192 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2277 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-11_17:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe 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: On Mon, Mar 11, 2019 at 04:16:33PM -0700, Matthew Wilcox wrote: > On Mon, Mar 11, 2019 at 08:49:23PM +0000, Roman Gushchin wrote: > > The patchset looks good to me, however I'd add some clarifications > > why switching from lru to slab_list is safe. > >=20 > > My understanding is that the slab_list fields isn't currently in use, > > but it's not that obvious that putting slab_list and next/pages/pobject= s > > fields into a union is safe (for the slub case). >=20 > It's already in a union. >=20 > struct page { > union { > struct { /* Page cache and anonymous pages */ > struct list_head lru; > ... > struct { /* slab, slob and slub */ > union { > struct list_head slab_list; /* uses l= ru */ > struct { /* Partial pages */ > struct page *next; >=20 > slab_list and lru are in the same bits. Once this patch set is in, > we can remove the enigmatic 'uses lru' comment that I added. Ah, perfect, thanks! Makes total sense then. Tobin, can you, please, add a note to the commit message? With the note: Reviewed-by: Roman Gushchin Thank you!