Date:   Mon, 30 Jan 2023 09:21:36 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Alistair Popple <apopple@nvidia.com>
Cc:     linux-mm@kvack.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, jhubbard@nvidia.com,
        tjmercier@google.com, hannes@cmpxchg.org, surenb@google.com,
        mkoutny@suse.com, daniel@ffwll.ch, Jens Axboe <axboe@kernel.dk>,
        Pavel Begunkov <asml.silence@gmail.com>,
        io-uring@vger.kernel.org
Subject: Re: [RFC PATCH 09/19] io_uring: convert to use vm_account
Message-ID: <Y9fEYNQOV0+iDvWJ@nvidia.com>
References: <cover.f52b9eb2792bccb8a9ecd6bc95055705cfe2ae03.1674538665.git-series.apopple@nvidia.com>
 <9f63cf4ab74d6e56e434c1c3d7c98352bb282895.1674538665.git-series.apopple@nvidia.com>
 <Y8/uyBKHf5XoXvTW@nvidia.com>
 <87tu08z2zv.fsf@nvidia.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87tu08z2zv.fsf@nvidia.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?H6dka3DOLzWRGXONRuFOc3k/GdVdkidsrpQdpgJUYZAxU23A4Khu2eW+c6eT?=
 =?us-ascii?Q?pswXVLkZBxVMv8ks9Gaok0papY7eoIY6v75eck/YT20hiwwsASRZYnt66WtP?=
 =?us-ascii?Q?wbGfmFNw1mq9y3NLC5vE4+ag+/uli3bE4fEEyvmpd3c8CUmeG7GBTgrGCMlx?=
 =?us-ascii?Q?izv2ETITbx9PbUy6AjQr93Ny/Iva8f1U3bnvhG6OkwiJLgpxgpPS/JlXkfc7?=
 =?us-ascii?Q?E0gvE4d00xmds2GAAAyUqG5Km0MHGnKYuHd/MkVhr/7ht2WT6/avZ98BKwH0?=
 =?us-ascii?Q?MhdC5dUke2H9JxVs34mOLXddYX6esNsiIl0LGEU780u5NzpuvIItGh6nX5J1?=
 =?us-ascii?Q?jFAB6RXUgmxvKFZNWnbDT7y4LHa+72l3dGATR5HMAndt+I5104dw29/Y1zso?=
 =?us-ascii?Q?hZIIywgmTH7mVtpwGOKsiVaRzMdE+RSby2ZkG+5juG6ucdvmZvhV3u8oxrkr?=
 =?us-ascii?Q?ngElQ8rh/M8g3wqm/sagvETG6/mq7AfU4hKJuM6iGWoh/AYdobVsMG5KaqMw?=
 =?us-ascii?Q?1/0PHrdmSCfju4IbHWPuECYZToN5E13pP8PlGmknx/yHqbw31E/Zf+FajHW1?=
 =?us-ascii?Q?dEjBucM+AsGpElv3z9MxoGakRDdSN8vGsOd6trojK10n9k0w3MKUzsw+lnpZ?=
 =?us-ascii?Q?/7cgITO5eQC6p7PWUGqTM3sQpnNzwzzsqkGIyt3MnkgR0L99b2IvNSH7H1Yv?=
 =?us-ascii?Q?MfKBzqla8a8g0JnW+6xY3KmvHys8o3FnMqW5iijeCPUBvJC+lezlUAV9M8Rv?=
 =?us-ascii?Q?BIi3R57Pc6hRpFo/Ulde3L3E/omahz7UYvr5yEJ0VA2ZTXHVRjLdfCJ/OFS4?=
 =?us-ascii?Q?iE3fEPpylO8CIoupjLUxifuKcT1lBHzhMfMwARaoPhohEblPKGZr4yS96Mlx?=
 =?us-ascii?Q?VhXNIXUCP1rUyqfbwiKTZOBTe5U8HlCEbYJk4EMxHqJMhveBKx9DCtbT9Elc?=
 =?us-ascii?Q?5Oa7OMkdYinQhHgXhYTj0IuW8/0YgtXBhkHKPACQ7q21dWnNZoKHlhFxTBsu?=
 =?us-ascii?Q?mfuVhdaeHdb7vLSXgBCw/BSGQiy+O64jHmwUtynkLk9IoCO74vBrLiXAeBX5?=
 =?us-ascii?Q?YXtk/3Dgyy+MwvVU9dUz6okqC2NQB3SW53oVX0MPo4Myt99fwmWHnTdkyIhv?=
 =?us-ascii?Q?dCDiZBhaRNLyjLomWfMSSdmIaV97OY2jYgvQ+q1nnmaWLKRsp/B2oYDU+B9b?=
 =?us-ascii?Q?pD8O1UEAvNebvLWj01jWg6UA8Rrv1MR+rBgPEW/oH82HNqWeMs9QbxUAKhOd?=
 =?us-ascii?Q?gOfKrwR2ESGs/Jedsx9AxfkU09nseBhCjDIKpiuufFVJeTkBpVwAnsSy5NBe?=
 =?us-ascii?Q?/AIVetr/xKl8G3CGLGPNrfB4QS8ch/sjZ0ksewHoQom4gDWV1F/AFxh11sOX?=
 =?us-ascii?Q?0tTLCXxGYSzVgZgjMWQKiKyYlPKt+YKvlv+GZvLv8KZLCmqp/+v/FXtLXZGE?=
 =?us-ascii?Q?rhdnlUcpD8n6SbTR7D7pHbDdFYoIJV9nLaquxh6KPjtDr3PkD5c2PFZPq4UV?=
 =?us-ascii?Q?UtXirwsDNPIGshj5dMQpCcdrlDTj/RbOVsyPh5F+iJG7zFHLGvoNfuAb/moO?=
 =?us-ascii?Q?CsoiyFfz7C7xvT2PmKODnbk7p6goXqGNh6ip7D1N?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: af293ff9-296c-4220-4b0c-08db02c4ea70
X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jan 2023 13:21:37.4380
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 8TIE2q8pBpV3Ggh7EBoCbEhn2gdoSwRoL/PT9uhHSiC2kudUyw5RuI9wnvGd35Rz
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB4963
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Jan 30, 2023 at 10:12:43PM +1100, Alistair Popple wrote:
> 
> Jason Gunthorpe <jgg@nvidia.com> writes:
> 
> > On Tue, Jan 24, 2023 at 04:42:38PM +1100, Alistair Popple wrote:
> >> Convert io_uring to use vm_account instead of directly charging pages
> >> against the user/mm. Rather than charge pages to both user->locked_vm
> >> and mm->pinned_vm this will only charge pages to user->locked_vm.
> >
> > I think this is a mistake in the first patch, the pinned_vm should
> > still increment (but not checked against the rlimit), though its main
> > purpose in this mode is for debugging in proc.
> 
> Sorry, didn't quite follow - are you saying we should always increment
> mm->pinned_vm and only use VM_ACCOUNT_USER vs. TASK to select which one
> the rlimit is enforced against?

yes pinned_vm was created primarily a debugging counter in proc

Jason