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Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Yang Shi , Mel Gorman , Peter Xu , Peter Zijlstra , Will Deacon , Yu Zhao , Alistair Popple , Ralph Campbell , Ira Weiny , Steven Price , SeongJae Park , Lorenzo Stoakes , Huang Ying , Naoya Horiguchi , Christophe Leroy , Zack Rusin , Jason Gunthorpe , Axel Rasmussen , Anshuman Khandual , Pasha Tatashin , Miaohe Lin , Minchan Kim , Christoph Hellwig , Song Liu , Thomas Hellstrom , Ryan Roberts , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 05/32] mm/filemap: allow pte_offset_map_lock() to fail Date: Mon, 10 Jul 2023 21:34:36 -0400 X-Mailer: MailMate (1.14r5964) Message-ID: <68C1B34D-B8B7-4151-B780-5A05812F402C@nvidia.com> In-Reply-To: <54607cf4-ddb6-7ef3-043-1d2de1a9a71@google.com> References: <54607cf4-ddb6-7ef3-043-1d2de1a9a71@google.com> Content-Type: multipart/signed; boundary="=_MailMate_9D30298E-0765-4062-B4C2-C2F5A4F416BB_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-ClientProxiedBy: MN2PR04CA0002.namprd04.prod.outlook.com (2603:10b6:208:d4::15) To DS7PR12MB5744.namprd12.prod.outlook.com (2603:10b6:8:73::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB5744:EE_|BY5PR12MB4289:EE_ X-MS-Office365-Filtering-Correlation-Id: b46b91ca-e24e-43c2-7b7f-08db81aefea8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?cLDOV2mgX4YhBn04a+gLNF0PKdd20FG8GtMQ/aPQETpMEP8rXjhpbzwIn1oX?= =?us-ascii?Q?ahcEleZNAyHJC4VZ/Ya91z0KQsbQoMGaqLpclMCMKExPLButHhZHyBH4cVyD?= =?us-ascii?Q?Ghml/OigjsBRdT7ioZQoRCK/mIVyLWjxSC7yJY1rrU6WmXWSwVzaiOWLaNEm?= =?us-ascii?Q?MzI1DuJbSkVepVa3CW4kL7R4rtxs/dlW1CkBTCZyoA2DJeyGmGfr5c9ZMThV?= =?us-ascii?Q?cfinjA8oXFmPsNOknqrBUj8o+un4m1nju1W6K0a1dqg9+qRoiFSWnHI/KzmO?= =?us-ascii?Q?+Nnr0uMpOTEZqMIjpYCf0bcxCaoUaDWAvhqRZmZX8LyH7qlnZytCjswZcXx7?= =?us-ascii?Q?iy+LW+0ERF5wPJiZda6V+Rs77/+fbxhkvc2tSrgG0BwbfbLpJIim39DohMCZ?= =?us-ascii?Q?6HEk3IY0F+jSrzK7EITXff7btrBaovu/GHVwv0fjCeZLldtN93CW/aIHbiT3?= =?us-ascii?Q?lxTChWEKgkCqet8Xul2KV14vBsRaAklsP9zdPnGfE8AWg+VuzcOaiCQAwAJB?= =?us-ascii?Q?EyX0KceH6WqNqvh63mCgiCohkrMPaCTXKIsVA4yLG33jwYLGVH/lbeF73+XR?= =?us-ascii?Q?avWRbPL9y5GyGgJDjPzLj1Fb6oCB5L3fVrwvYANuy2UCeqcljBRUMlQDmokf?= =?us-ascii?Q?IAIFplTZ7nh+bvyW0EHD/kYUJdsM6acB+ra6acuDLT8gg27We651rUXhJaO5?= =?us-ascii?Q?4x4lgOy+56NU4pOCBkm8CRzt7LvxqmlJMsN/6RDw6bkOf9rlUd4Mmuz/aNMg?= =?us-ascii?Q?MuFT+zQlecKC98LrRm3fIMacA6gB/5FXh3aB6VvwICaY4Or5CnaylspsrDfY?= =?us-ascii?Q?NsDwquH6hayXjhp4uur0kN0HDxmukMN3kuk5zY+qAeNfenZMatkwj3C+wSEU?= =?us-ascii?Q?7mGTSvstXjaCiHdk7scca3I/gFMOHAr62iKXI7BhAxTjSXRPyULxtJx5gKh6?= =?us-ascii?Q?QUxYJA4jZyq6wrdynfgKYv2D4osGPvVCB2dOsJscS0vcR+8UnUhA/WPb4s7p?= =?us-ascii?Q?sEgsOsEqkCe0Wi7SKEzdDsmtRwZe7BXV78R8aiNSb9/rvB7Vv2nyIDDwae8z?= =?us-ascii?Q?Z/mmzRfFSnN4BrRSGxPwiCUBjwFyT9wVD/5YBrAF6T6Rryc5IzxQaVhm+OAy?= =?us-ascii?Q?PuBUrQTww5rhdVk1gHpm9D8QpzMgncc4zTjhH50J54ik+CQTAztTes+f2hp3?= =?us-ascii?Q?4Lf6QBxv/u78BQVEUoJoBHuDhlb7Q9+loUhRTpMhrNl2oeC+DI7xLrZvVpoV?= =?us-ascii?Q?mcmxO+mR7EFDZ2yOlAirLCkXZ+HQieCy9ePUJdWtkTCduLv5cEu0tS9xxZ/+?= =?us-ascii?Q?L51MZBHJLcqUDRnFreP44qF0l2NvaANPo7uWvPdSBr2dTPEeJ9GshdXVOITn?= =?us-ascii?Q?CSK5nIvzXwi59HRn4t7IghhrzZKe9nuAx7J/Porek1WxoP4bZt+qwYL5MkLH?= =?us-ascii?Q?MCrAfAUssHzPKsfwzNCfHAlCjUZkiMpbBmmchnE9RZ32ocv86O0WpNildm0M?= =?us-ascii?Q?B+N5ky2IFtdkB0LRJdIu3BftZD8eImFuj+sG5oIQSEk9zPhjtyk6LzbIjodb?= =?us-ascii?Q?eWOZOIHWnglScv5q3Es=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b46b91ca-e24e-43c2-7b7f-08db81aefea8 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB5744.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jul 2023 01:34:40.1693 (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: xxc8aR1ZtIcAmxnTXV9djulzmZTNHlIY10oihlO9Af7qWnbsV/8hFRGmMOLHX+wx X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4289 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=_MailMate_9D30298E-0765-4062-B4C2-C2F5A4F416BB_= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On 8 Jun 2023, at 21:11, Hugh Dickins wrote: > filemap_map_pages() allow pte_offset_map_lock() to fail; and remove the= > pmd_devmap_trans_unstable() check from filemap_map_pmd(), which can saf= ely > return to filemap_map_pages() and let pte_offset_map_lock() discover th= at. > > Signed-off-by: Hugh Dickins > --- > mm/filemap.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 28b42ee848a4..9e129ad43e0d 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -3408,13 +3408,6 @@ static bool filemap_map_pmd(struct vm_fault *vmf= , struct folio *folio, > if (pmd_none(*vmf->pmd)) > pmd_install(mm, vmf->pmd, &vmf->prealloc_pte); > > - /* See comment in handle_pte_fault() */ > - if (pmd_devmap_trans_unstable(vmf->pmd)) { > - folio_unlock(folio); > - folio_put(folio); > - return true; > - } > - There is a pmd_trans_huge() check at the beginning, should it be removed as well? Since pte_offset_map_lock() is also able to detect it. > return false; > } > > @@ -3501,6 +3494,11 @@ vm_fault_t filemap_map_pages(struct vm_fault *vm= f, > > addr =3D vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT= ); > vmf->pte =3D pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->pt= l); > + if (!vmf->pte) { > + folio_unlock(folio); > + folio_put(folio); > + goto out; > + } > do { > again: > page =3D folio_file_page(folio, xas.xa_index); > -- = > 2.35.3 These two changes affect the ret value. Before, pmd_devmap_trans_unstable= () =3D=3D true made ret =3D VM_FAULT_NPAGE, but now ret is the default 0 value. So ret s= hould be set to VM_FAULT_NPAGE before goto out in the second hunk? -- Best Regards, Yan, Zi --=_MailMate_9D30298E-0765-4062-B4C2-C2F5A4F416BB_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEE6rR4j8RuQ2XmaZol4n+egRQHKFQFAmSssa0PHHppeUBudmlk aWEuY29tAAoJEOJ/noEUByhUzu0P/RasOUfRsb1uFZRkZyAwOaCy+cBQmc6bzaR7 wGJkMjsyfYMebEXtmpqsO5VpsTzDLC0LE5CQH//hRP6XGS16aF6oexlo1FB9j+Q9 74lZibnKBxtlayO/v5xWg6Dq4pagOxCPp2EkbbYyAr+ZCOgVYO6ANBHBezJh1QkW ju0WfI7wFlhjxd/JcmFrHjeqgglfBF09jz5EPkWJ2R1JQgbAftXAIVmOfbxE9RrH vlnU8FsrR3wvTZUmmZcXPBqgx559FYxuThWo9ZbY9H8sqH8pggN9CBKrsSSeuisz 1dRG0PybbrKBBAHDOjeEze/xOQ388SlSY/m6Go5dyKYPyZAXFplx8afXmsZIpI+6 IixH/oflqLM4QMSJ9+CExFjS80xoallkktnE7ysVksRD4/LwV3gU8YhoWMK4v0/w WjakImXetyPeEDqIWkFFIFO5iuNJRV1f/n0PihjgfEvo4Ft/WO98XR4Z7Weuw4yF eDc3vz84n/gRy6B7PC4zkGPR8/Y3prvDVS1RFyXY5P40/wPV8XUSp+mg+AU+9vIc ucBmdIdrgqzl9G96zaHXvdJDmvBzPCp9PwY338FpqxIp5YWrAWI3CM8hcTFSTEiC QZzz1gixbiClP8q4+ncdYMEWqmwgI2fxdfXbwf+ef/LxAepBPkf53/YW05A2dmcT JOG8SPmr =SJHj -----END PGP SIGNATURE----- --=_MailMate_9D30298E-0765-4062-B4C2-C2F5A4F416BB_=--