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Wed, 8 Sep 2021 22:42:28 +0000 Received: from BY5PR12MB4130.namprd12.prod.outlook.com ([fe80::6811:59ee:b39f:97b9]) by BY5PR12MB4130.namprd12.prod.outlook.com ([fe80::6811:59ee:b39f:97b9%7]) with mapi id 15.20.4500.016; Wed, 8 Sep 2021 22:42:28 +0000 Subject: Re: [PATCH] mm/page_isolation: don't putback unisolated page To: David Hildenbrand , Vlastimil Babka , Miaohe Lin , akpm@linux-foundation.org Cc: iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210904091839.20270-1-linmiaohe@huawei.com> <3b36529f-ab97-ddfe-0407-66f0cd1fd38d@redhat.com> <2d06db75-5c26-8fe2-6883-ac99056a9894@redhat.com> <80cfffdc-227e-c045-be74-1c08fb62c1e3@redhat.com> From: John Hubbard Message-ID: Date: Wed, 8 Sep 2021 15:42:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 In-Reply-To: <80cfffdc-227e-c045-be74-1c08fb62c1e3@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR02CA0031.namprd02.prod.outlook.com (2603:10b6:a02:ee::44) To BY5PR12MB4130.namprd12.prod.outlook.com (2603:10b6:a03:20b::16) MIME-Version: 1.0 Received: from [10.2.63.205] (216.228.112.22) by BYAPR02CA0031.namprd02.prod.outlook.com (2603:10b6:a02:ee::44) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4500.14 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZFkvbGJLZ2RXVmdZQ2Q5VWlVNEdiK2sxYjlRczBHbVJNcVdjVlF5MnFXa1RS?= =?utf-8?B?Z0x4R1VxVFFOQ1VENEExWnNSYTNtUitoY05LOUY3ajBVR3c4Z3h0ZEtQdTRo?= =?utf-8?B?SXdPZUxSMktnNmozMjVQUHEzN0lCbzlqdzBOSVI3UHZ1VHJNNWE2eVY3RHdj?= =?utf-8?B?bmoyWWxHOW84WTg3TFBJUWNZdDE2aXV0aVlTYjBGdXRGWXAwZW5tRXA2NDRt?= =?utf-8?B?VytjSDlROGI2clBOU0VnbUtIM0JkbFdnVXE4YVpaMmllZ0U4R1JMaGYwMkVs?= =?utf-8?B?b3MwM1F5TVlKV3dycGZuOEl6c0hGQlU3V2l0UWx4N2ljVDc4ckpmODhobTlh?= =?utf-8?B?ZEptRUZnSEtaMjhKSzhCWlRsdEJXUnkzV0dXNG1tTzJrK2g4UnNGR3NYSlhZ?= =?utf-8?B?R2hxR1ZJMS9aMlVLak9Uci9HckIvZXFYK1E2YWhRU045V0VzdURNRmRrcWl0?= =?utf-8?B?d09zUWVDWGFLL3haVlhtQzZxZksvTUZrYVRnVTlwL3p0bnBURlljMUEzYXFi?= =?utf-8?B?dGMwZ05LQ3I3M0RiUDVBVWIxVW8wQ09TUG1lVk1OK2xzT2pZL2RheUpMMmdT?= =?utf-8?B?cWQ4ZGdaM3k3OERXUXFsaEpHUVdtbjhOZ0VZMnR0bnJHRmg5UGJkemM0YkFt?= =?utf-8?B?ejJmQmZMY1A1RkFpYllWR09kTWZDNG5oS0RJeloybFdBY0ZYd0NEcFFQd3JO?= =?utf-8?B?WFZBM1FDVCttTTlHa3pYTkptdUVmZ2lFakMrK1o4M1dVY1V5djdGUjJDb1Nq?= =?utf-8?B?K0JRWTBZUE5sVE1MaVIvR2Q2ZFJXbThLVkY1QTZSSUNwVHVxSEl5cFJMeCtQ?= =?utf-8?B?UVFKUzNlZ25oRDRacnNHTUlLYmo3MnFQdXppcDBKQVdIeXhzNTBTbldYUTcz?= =?utf-8?B?ZXBicCtEUFZVWFJTMTdtekRNS0pyOEx0Y0EraE1GcjBRSkJjU3NGV1dJeHBR?= =?utf-8?B?V1VnQWo5RXN2SmM5KzBVWmY3aURCd0ZobHBmVVBDdUNGakNnRGNmRzZBWU5E?= =?utf-8?B?UUZ6S0IrMXB6ekFuV2xveUxlZ0JYYVdRd2RhemhKcDkwOFhLL1pDVGNmSkNk?= =?utf-8?B?eHNYT1ZtTTR0VjVCMXJ2QXVSaDlPMDh5elNwTHc3dUs4bUNHMHJyUGc3MnEw?= =?utf-8?B?NWJkTlZCOEQxUmdCdHJsSXFQM3FzNlNXNXdES3JjN2FMc2tYNmltUjY4RUtM?= =?utf-8?B?M0hjaDl3WE1Oam13ZnpuMXBqcGIrTm5OYVJSY0RPMGlGSGlNYmwwc29NeXkw?= =?utf-8?B?RG1oSW05QjlXQnoyeUNHMWJKcm1tdG1WTUNiOVZvbTdnbDZsaXpMb01BeVNI?= =?utf-8?B?bGxHSnZ5eVVnWm9DN2lwWUJkcy92QnBRNUJEQXppNUxiK2xNZFM5eDU5VjN5?= =?utf-8?B?a2IrNkFwM3JIVVBHRkc0WHVvQWxpcm1lc3VUNHRPeHRyUlE0SmdXbGtWVHVq?= =?utf-8?B?ZDJQelJ2QzliRDlBMTVOL0VPWWp3SkVmKzFJWlRCVkJERHh1Nyt6SHp0ZWFh?= =?utf-8?B?NDB0OFNlTVlhUmJWVkxVTmkxS1RuZXZyZ1d6MzZ2WEdiU25YeHgrL2hlU1pU?= =?utf-8?B?U1JXeS9KSktpSnFkUFU0dEVzODZGZS9RSTVzRlBEM1gxVnNFWEV0NGloN013?= =?utf-8?B?U3pDUlN1MkdRWVVkb29RaVdjd2w5NXFmbExiL2JWMTQvNndXRHBuU1V6QTFD?= =?utf-8?B?UUhJRjNXWXM0VWN6Zi84THpZM1hQRFZhayt5enVHN000WXltamtIdG11Ry90?= =?utf-8?Q?xJF33NzWBZRwGADoW0lDcF4fRfEVuj5UuRGg6SF?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8c54ebc7-36ef-4e27-e088-08d97319efc9 X-MS-Exchange-CrossTenant-AuthSource: BY5PR12MB4130.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Sep 2021 22:42:28.7213 (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: pDaUNOVL8ANp2atITFkJ+3fE/PCWqhChzk4iTk5lG8GtH4l+Adb77bK6+EKztQ+C7VoLyOMU/0gu2wFwxrKtXA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB3064 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/7/21 2:56 AM, David Hildenbrand wrote: ... >> If this can be handled gracefully, then I'd rather go with VM_WARN_ON. >> Maybe even WARN_ON_ONCE? >> > > I think either VM_BUG_ON() or VM_WARN_ON() -- compiling the runtime checks out -- should be good > enough. > > I'd just go with VM_BUG_ON(), because anybody messing with __isolate_free_page() should clearly spot > that we expect the current handling. But no strong opinion. > If in doubt, WARN*() should be preferred over BUG*(). There's a pretty long history of "don't kill the machine unless you have to" emails about this, let me dig up one...OK, maybe not the best example, but the tip of the iceberg: http://lkml.iu.edu/hypermail/linux/kernel/1610.0/00878.html thanks, -- John Hubbard NVIDIA