Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Roman Gushchin <guro@fb.com>
To:     Vlastimil Babka <vbabka@suse.cz>
CC:     Roman Gushchin <guroan@gmail.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH 2/3] mm: separate memory allocation and actual work in
 alloc_vmap_area()
Thread-Topic: [PATCH 2/3] mm: separate memory allocation and actual work in
 alloc_vmap_area()
Thread-Index: AQHUzUkHvmEZiK9g+UuhGR24XSYfTqX236aAgAAjAQA=
Date:   Fri, 1 Mar 2019 16:48:41 +0000
Message-ID: <20190301164834.GA3154@tower.DHCP.thefacebook.com>
References: <20190225203037.1317-1-guro@fb.com>
 <20190225203037.1317-3-guro@fb.com>
 <db6b9745-7e64-6eb9-6b2b-da9d157a779b@suse.cz>
In-Reply-To: <db6b9745-7e64-6eb9-6b2b-da9d157a779b@suse.cz>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-messagesentrepresentingtype: 1
x-originating-ip: [2620:10d:c090:200::1:7a0f]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: 0aedf333-3195-4c5e-9076-08d69e65c244
x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600127)(711020)(4605104)(2017052603328)(7153060)(7193020);SRVR:BYAPR15MB2869;
x-ms-traffictypediagnostic: BYAPR15MB2869:
x-microsoft-exchange-diagnostics: 1;BYAPR15MB2869;20:pZqoy77TZneKHPbZWFPsf1hffR/n97bXgdLEGOawnn76ZG/N/QXUTam3Xai2uyhTwhOTsheYklmiY80v28hLRNJmdgPyriAEtfVQLLmEzxeiyNQUSiMB/VxMPYKFHIDxZlCfovoucCfZ7U9ny7BBog32lHQDlkac1rvpft+0G9o=
x-microsoft-antispam-prvs: <BYAPR15MB28699704F17D8024FD9EC0E6BE760@BYAPR15MB2869.namprd15.prod.outlook.com>
x-forefront-prvs: 09634B1196
x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(136003)(346002)(376002)(39860400002)(396003)(199004)(189003)(6916009)(476003)(446003)(316002)(11346002)(486006)(7736002)(1076003)(33656002)(54906003)(97736004)(46003)(81156014)(102836004)(8936002)(186003)(386003)(81166006)(53546011)(6506007)(99286004)(106356001)(8676002)(52116002)(14454004)(105586002)(6116002)(478600001)(53936002)(4326008)(25786009)(6436002)(5660300002)(305945005)(76176011)(6486002)(6512007)(9686003)(68736007)(2906002)(6246003)(14444005)(256004)(71190400001)(229853002)(86362001)(71200400001);DIR:OUT;SFP:1102;SCL:1;SRVR:BYAPR15MB2869;H:BYAPR15MB2631.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX: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: Gd016rsieWHZhRa6i464bFw38vIBLldCVt0T/TK8VaKbsJjmZQOK+H7jIdWqbVbgXdEMB9TjIkq9aJxxDPP1/uyzXlyCEX33MP4hpLDWjcU6tomdvhKw1RlWDOUg3fKGlSdre3Hnnq0m5nvvo7kbIEEgZPP8wDy++oVmTJTWNFlK1vRuKCkhe3sEFzWqeomvTx2ZNqI+TeQ6oFJL7qpMpEOGk2vhTpPIsLMjAyhLLdWfiK0h1q8faaL94iE7LjpYuJOmu8q9bjNU4+OxPxOpgy/IRTL/VjA2ZOr/uF/BFVPR8Lrvp6RNEzh2OMIanhXQfNg0w5n8wMp72HsWE7oe+q+l8+o0suRssx7D/LXt/gLjBOJTRwI7MLjH8/v10yPap0u32iCNBjDV8hYeNMuniHJu3P5phV/UqYFbDtkQod0=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <03383EF3FB7B234EA2B739C4591BB3F0@namprd15.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 0aedf333-3195-4c5e-9076-08d69e65c244
X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Mar 2019 16:48:41.1645
 (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: BYAPR15MB2869
X-OriginatorOrg: fb.com
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-01_12:,,
 signatures=0
X-Proofpoint-Spam-Reason: safe
X-FB-Internal: Safe
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Mar 01, 2019 at 03:43:19PM +0100, Vlastimil Babka wrote:
> On 2/25/19 9:30 PM, Roman Gushchin wrote:
> > alloc_vmap_area() is allocating memory for the vmap_area, and
> > performing the actual lookup of the vm area and vmap_area
> > initialization.
> >=20
> > This prevents us from using a pre-allocated memory for the map_area
> > structure, which can be used in some cases to minimize the number
> > of required memory allocations.
>=20
> Hmm, but that doesn't happen here or in the later patch, right? The only
> caller of init_vmap_area() is alloc_vmap_area(). What am I missing?

So initially the patch was a part of a bigger patchset, which
tried to minimize the number of separate allocations during vmalloc(),
e.g. by inlining vm_struct->pages into vm_struct for small areas.

I temporarily dropped the rest of the patchset for some rework,
but decided to leave this patch, because it looks like a nice refactoring
in any case, and also it has been already reviewed and acked by Matthew
and Johannes.

Thank you for looking into it!