Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 6 Jul 2023 15:06:12 -0700
From:   Mike Kravetz <mike.kravetz@oracle.com>
To:     Jiaqi Yan <jiaqiyan@google.com>
Cc:     naoya.horiguchi@nec.com, songmuchun@bytedance.com,
        shy828301@gmail.com, linmiaohe@huawei.com,
        akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, duenwen@google.com,
        axelrasmussen@google.com, jthoughton@google.com
Subject: Re: [PATCH v2 2/4] mm/hwpoison: check if a subpage of a hugetlb
 folio is raw HWPOISON
Message-ID: <20230706220612.GA3768@monkey>
References: <20230623164015.3431990-1-jiaqiyan@google.com>
 <20230623164015.3431990-3-jiaqiyan@google.com>
 <20230705235705.GE41006@monkey>
 <CACw3F511Hk-XM46fYnciKy6=t0bdmGpu9y1qsqrpJOA0zFKWhw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CACw3F511Hk-XM46fYnciKy6=t0bdmGpu9y1qsqrpJOA0zFKWhw@mail.gmail.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?MkJlRE5hMkR2OEtya0Z0dk9yQkFJZjdFQ3NlZjJrWkdXNUlNcWl2OFNEQ1hr?=
 =?utf-8?B?MmJZTHpFYXBUK1QwV2djcjFMaDdnWlFTSzBZSW9FYWlBOEJPYXYydy9JSmhO?=
 =?utf-8?B?Y215U1R2K1E2c0xwa0FmSk1pdGVzR2JHL3hhUkdkMk1TMjhlUXJoT2VmZjBC?=
 =?utf-8?B?T1kzdzZyaktzalVFT1JhV0xqdDlCTkhYTmZ2amw1V0p6azRkTFN4TDhDeGVu?=
 =?utf-8?B?ZmNUSXJVeXRZaGltODVnOGYzb0ZTYldGSDdFaFcxREZkeUpXSks1N0xIdTNG?=
 =?utf-8?B?UlhTK0EyYzhsUDY1Q2JzODlQSDY0dTVPY240VlBhWUxIcGJjUzY5WjNUUUFE?=
 =?utf-8?B?Sm0xcUFQL1ZnVFd5OEhoWmkydVlCRUUrcnBIbFQwS1lpY3NUeW9ZbkdJK3Ry?=
 =?utf-8?B?Y1ZkSUZhL2srRTNNd1czZEg4Tmc2eDJud0JZYlh5UnVmUnFNM25XWUZQUnRn?=
 =?utf-8?B?R2tMVzhvUUlxRFU4SGt0K0NJeGoreUJPNjFQQWxVN3NRcnliQlcxU3RpN0Js?=
 =?utf-8?B?VHg0a3BZWTlpTlA0MGpLREFjVk5ydld5Z2Z5NnVtcHdRL0VVUnhYaDd4QVA0?=
 =?utf-8?B?MDVudGJHQ29yQjdTYjAvbFpzUW54ZUpRdmJrVGxta25Ka0ZES3VxSldnUUxr?=
 =?utf-8?B?WUVETWZtOHNaeGFKUGxOcTBhNk45WVgyOTA1U3o2S0ZnV2llSytVQ1FFT2RI?=
 =?utf-8?B?YWVCY001a050UkQrRjFXUWVsdkxjeEo0NHJkdWd5V1NOT1NBcUtzOVl2R2Iv?=
 =?utf-8?B?UWNiTTJpcmY4cUdJRGRIWXZaQXQ5eUpqSDJ4dmJDSko3UjlYb1ZPMWZ1aGdM?=
 =?utf-8?B?QlBSWjN4Z01KeVhmSHh6Snh3ZnlpT2VmNzRhTTNIbWt1dkdkajJycUJtbVdX?=
 =?utf-8?B?UVBMSGlxbWlCQWxhOVhKU1VmRko3eG1MWHcxRmlUMlo5SE9pZ1hhb0ZOQXZu?=
 =?utf-8?B?clJqNFc1REQvQ2dHdWd1TlhDU0NIbzNqaHN2aVVsMHIyYkxFMzhPc1NBaTJo?=
 =?utf-8?B?ZmZBR2U1bitqcDBldEFaSkxWYllOOTF6Nmk1cmlKNng4bzJYKzdqNlZUM0dn?=
 =?utf-8?B?TWhhb1RhSXhMa1dqL1k4REpCRTJOLzJ6SzBiYmxUa1BJM1dyTE9QRXIyWjNh?=
 =?utf-8?B?cGZiWVBpaXlidFZRMWpGTWFuSnJNdzgyampsbkxhZHhPUG1la21KU0xHRWNY?=
 =?utf-8?B?Qko2TVpYYUxXZWFoNXVVM3ZzSmprTnJqVkxLYjVrcnlhMUZkNkVQOVpLaFdr?=
 =?utf-8?B?RWwyQW1OcWxqMnFLRGNOVXFtQ0JHWUdqN29naHcxdC9CaUN4YkJQZGd6OFZ3?=
 =?utf-8?B?NU9nSld4Smx4dlU4Z0dmbUNTcm9tODB0VnRvdXhhMURxNjNMclNndnUyVjI1?=
 =?utf-8?B?RStIeDlyMktWSmdieXFvc2RTL1JrUlByRU50Rit1ZWhTTkozSzBtaTM5Z1RL?=
 =?utf-8?B?anhvaXkrWUhxR1ZScUp5MnhLbC9ZeUlrZWdSMEhPZEFyMFVrVFhPU0gzTkFI?=
 =?utf-8?B?Q2o0Z3I4M3dRWUR2Y3lmdHE0aENUODdsdE5oUzA1cDBNVHg2Z3hHNkt4Yk5W?=
 =?utf-8?B?c2RJc3kvMERNZXhMQ2JyNEt2anV4UTQ2dXVoeW5mbnQ5YW1zUlBWYlFxdGY4?=
 =?utf-8?B?RHN3UUtIZWhNcjI1cHorSzlYdy8ra01CSjBBTnpsZlE1TFB3VWZJSlA2eEdw?=
 =?utf-8?B?Y2ZnWUo2ZVg3QTJ1MjZ2MVZKRzZIN2ZJcmVjWjFOYlh4SkFYMXAxNWgzaUk1?=
 =?utf-8?B?N3FFNWg5R1Judzh1eGlCMzZmR0x0YjRSNnJuWTFkWWlBZTdEdFJNU25pMjZ3?=
 =?utf-8?B?QzQyQk5paGF6eFBQVlJ4MTZlVDBJbEVETDNTQTNnY0xDd3NqVkpQQWRwUG1F?=
 =?utf-8?B?ZGsydHhnaTIxa3Y0ODI1UGh6WHNmSlYxdUd6a0JaMjBvc3BISHI5NjNjV29W?=
 =?utf-8?B?QW5kNUNIZS9CbUxNb1k3MzBLUE12aEpPUXpQYTlpbEpJdEJpK3RmZGhINStQ?=
 =?utf-8?B?S0U5RkdXNkV5c09DTFNFNStDNmI5Nm9ET1BWa2ZoRXhWYmhZK0ZvVWtiS3NC?=
 =?utf-8?B?Uno0ZjlDeTJLaFZhK1dMWjdtT0tJdGk1NHZqMmpPeVRDcVVyckZKZWRTWksv?=
 =?utf-8?Q?MOVFD0uouK4nckujuwopue9l8?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?utf-8?B?M3A1ZzV2NUx0c3FxWVRkZld6MlE1aDJPK3JSQlJuVGhuaFBQS3V2L2tBdTFI?=
 =?utf-8?B?dXR1RzJkbFYxRVZudmVWTTBSb1VNSHhOWnlLT1ZIZTN2MEFoVEF2M2hHMDl6?=
 =?utf-8?B?dzlvdCtCRnA3OXMyYjE5emMxS0NvOU1zK2tuUHJwVVZPZy9seE42K3RMdEcx?=
 =?utf-8?B?Z3Q1bC9ZMVcvYkExTlhtczFkdnU3MlJsK1ZQTDk0ak1oNi8xSzNtYWRkQmNN?=
 =?utf-8?B?WDJvak1TdTdqSmVxc0o5TlZXU0tHN1AreHNybTFaa3J0aURtSmV1bmhFa200?=
 =?utf-8?B?L1NOclo3TVJjNkNqS2hhOXZ4V1hMWHAzc1pOcXdjRjNKdDBHd1MvOXJKMjBm?=
 =?utf-8?B?aDhsRjh2UDBwSE9Oc05DMnlQVHRnWlNTblEyTjZoYW1hcnE4QzZONlhSanIw?=
 =?utf-8?B?VTUyVkYzZmsxSXpQMWVlRDA1SmZVOU9zb3ZQQjNWTXBWeW1pRi9FOVo3V3Jm?=
 =?utf-8?B?bkJxVFlVNXczTTVvQlN4NnJmYURuRStGMmRHOFZ0REtFa1FWTzJ1RDh6ZTVG?=
 =?utf-8?B?OERWRUhGVTRRZmhnQjhMY0NrVldQbk1VamZaN21wU04zOHJ0SWlHKzF4R2NU?=
 =?utf-8?B?TUNrZHNnTEJrZ3NiSmwwc0lURUxuRTE1TEtrSmVHbDNpcUx4MkowSFkwUG5U?=
 =?utf-8?B?MjE3czA1QTBoZ0NmOThWSDljWlVod015ckpCSWp1dWVmTldKVG9rSmRsVCtw?=
 =?utf-8?B?TExaTFdTUS9WbkQ3N3k2blBabTZYZ0l3Rnpod2JPWFhnWFNyZ3NhcTNQWnVq?=
 =?utf-8?B?VjBuMmR3R2VMMDljUms1NmFHRzFuWnJkV1JjTHFvZHZERXY0dmtjU0kvYnBS?=
 =?utf-8?B?bGlEYitSREpjZ1lNSVUza1VVU2hGeFpDelJSY0dQSUF1MXdzQUpxSVNTNzRu?=
 =?utf-8?B?MFBpSTJjMGtrdFQrN1pOVFp6Q1IwaWs0U0ZoNzgzQzZ6RmlObVhqV2J4d2xK?=
 =?utf-8?B?WmJ5aWkvRGtWSDI0RnJuQmVNeVZuZFBISGhwZ2VDU3YrR0hyZGQ4M3pnT1M2?=
 =?utf-8?B?SGxCVFBYZ1J4T1lrZlJvdTN0RFFSNGRZTUlIN2l3cDVlNHlOMUZ6OHZzQkpJ?=
 =?utf-8?B?OEQ1LzUvQWk2dGlta3VCMjF6Q29jUS9SektUcEUrR25ySmZYbE9MMmtYYUk0?=
 =?utf-8?B?Z2M0Mm1uelY0NUhOZ0RIQW9kQ2lCaU1mOCtIWlhFR016VXVJWGVnOTlhUDA0?=
 =?utf-8?B?dVhGaVBzYi9oMElaaDdXaGZjYVhDZzlQKzlQakNzZVdCSm52ZTNoRm8xc01D?=
 =?utf-8?B?TWVyT0prZmtBM2lidFV5WjFOeEJUTk1PRm9hVENQdzJTMUp6L1ZHeW8vbTBM?=
 =?utf-8?Q?B+ryevA0NMZHQ=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: f0925f64-ac97-4280-12f2-08db7e6d3770
X-MS-Exchange-CrossTenant-AuthSource: BY5PR10MB4196.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Jul 2023 22:06:15.2059
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: RJhU51yXH+01LvIswHMtLq9rn0+Ule67+a3vS1mvHCWx7v17w0XDT2X9O5RCUaZr5qwe2dpv+yUBPOVDYpCoow==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR10MB5718
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26
 definitions=2023-07-06_15,2023-07-06_02,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 phishscore=0 bulkscore=0
 malwarescore=0 mlxlogscore=999 adultscore=0 spamscore=0 mlxscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000
 definitions=main-2307060193
X-Proofpoint-ORIG-GUID: iZ4oSq_XNN-8WnvdufQURWs4MkrEN398
X-Proofpoint-GUID: iZ4oSq_XNN-8WnvdufQURWs4MkrEN398
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 07/06/23 11:25, Jiaqi Yan wrote:
> On Wed, Jul 5, 2023 at 4:57 PM Mike Kravetz <mike.kravetz@oracle.com> wrote:
> > On 06/23/23 16:40, Jiaqi Yan wrote:
> > >
> > > +bool is_raw_hwp_subpage(struct folio *folio, struct page *subpage)
> > > +{
> > > +     bool ret;
> > > +
> > > +     spin_lock_irq(&hugetlb_lock);
> > > +     ret = __is_raw_hwp_subpage(folio, subpage);
> > > +     spin_unlock_irq(&hugetlb_lock);
> >
> > Can you describe what races the hugetlb_lock prevents here?
> 
> I think we should sync here with __get_huge_page_for_hwpoison, who
> iterates and inserts an entry to raw_hwp_list. llist itself doesn't
> ensure insertion is synchronized with iterating from
> __is_raw_hwp_subpage.
> 

Ok, makes sense.  And, since this is only called in the file read patch
when we encounter a PageHWPoison(page), the overhead of the lock cycles
is not of concern.

You can add,

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
-- 
Mike Kravetz