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McKenney" , Matthew Wilcox , Laurent Dufour , David Rientjes , Axel Rasmussen , Suren Baghdasaryan , Vlastimil Babka , Rik van Riel , Peter Zijlstra , Michel Lespinasse Subject: Re: [PATCH 01/94] mm: Add vma_lookup() Thread-Topic: [PATCH 01/94] mm: Add vma_lookup() Thread-Index: AQHXPEQmA9/hNjlhF0O1j8k1xuPy8qrOFnOAgAPeL4A= Date: Mon, 3 May 2021 16:08:47 +0000 Message-ID: <20210503160841.2juynuimujnaajad@revolver> References: <20210428153542.2814175-1-Liam.Howlett@Oracle.com> <20210428153542.2814175-2-Liam.Howlett@Oracle.com> <20210501050441.GB5188@lespinasse.org> In-Reply-To: <20210501050441.GB5188@lespinasse.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: lespinasse.org; dkim=none (message not signed) header.d=none;lespinasse.org; dmarc=none action=none header.from=oracle.com; x-originating-ip: [23.233.25.87] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 927b1c9d-a469-4b78-b9e9-08d90e4dbbc5 x-ms-traffictypediagnostic: CO1PR10MB4481: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8882; 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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MWHPR10MB1582.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 927b1c9d-a469-4b78-b9e9-08d90e4dbbc5 X-MS-Exchange-CrossTenant-originalarrivaltime: 03 May 2021 16:08:47.3824 (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: rH6BcUNTTgzZHXwcZvOqOcCkxAYg9akR/LO9GgtzwJ87Xjds4nrwm+RlY7a7wzORypctefxM2k4JoTgSFaW5Pg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO1PR10MB4481 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9973 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2105030107 X-Proofpoint-GUID: _q0Afz_laPpgdnUgt6wikDrE3Oznmd45 X-Proofpoint-ORIG-GUID: _q0Afz_laPpgdnUgt6wikDrE3Oznmd45 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9973 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 mlxlogscore=999 suspectscore=0 priorityscore=1501 phishscore=0 malwarescore=0 impostorscore=0 clxscore=1015 bulkscore=0 spamscore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2105030107 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Michel Lespinasse [210501 01:04]: > On Wed, Apr 28, 2021 at 03:35:43PM +0000, Liam Howlett wrote: > > Many places in the kernel use find_vma() to get a vma and then check th= e > > start address of the vma to ensure the next vma was not returned. > >=20 > > Other places use the find_vma_intersection() call with add, addr + 1 as > > the range; looking for just the vma at a specific address. > >=20 > > The third use of find_vma() is by developers who do not know that the > > function starts searching at the provided address upwards for the next > > vma. This results in a bug that is often overlooked for a long time. > >=20 > > Adding the new vma_lookup() function will allow for cleaner code by > > removing the find_vma() calls which check limits, making > > find_vma_intersection() calls of a single address to be shorter, and > > potentially reduce the incorrect uses of find_vma(). > >=20 > > Signed-off-by: Liam R. Howlett >=20 > This seems like a good API to have, and I agree it's less error prone tha= n > having every caller check the vma->vm_start address. >=20 > Minor nitpick, I would prefer if the implementation used find_vma() > and then checked the vma->vm_start address - I don't like using [i, i+1) > intervals to implement stabbing queries. Okay, I will make that change. >=20 > But other than that, I think this (and the other patches adding > corresponding call sites) is safe for merging. >=20 Thanks, Liam=