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Mon, 9 Jan 2023 06:47:56 -0800 From: Yishai Hadas To: , , , , , CC: , , , , Subject: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly Date: Mon, 9 Jan 2023 16:47:01 +0200 Message-ID: <20230109144701.83021-1-yishaih@nvidia.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN8NAM11FT093:EE_|MN2PR12MB4096:EE_ X-MS-Office365-Filtering-Correlation-Id: 4c011757-627f-4d61-a566-08daf25085aa X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.233;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge2.nvidia.com;CAT:NONE;SFS:(13230022)(4636009)(136003)(396003)(376002)(346002)(39860400002)(451199015)(36840700001)(40470700004)(46966006)(1076003)(316002)(5660300002)(40480700001)(26005)(7696005)(186003)(478600001)(2616005)(40460700003)(426003)(47076005)(41300700001)(110136005)(70206006)(336012)(54906003)(4326008)(8676002)(70586007)(82310400005)(8936002)(83380400001)(86362001)(36756003)(6666004)(107886003)(36860700001)(82740400003)(356005)(2906002)(7636003)(2101003);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Jan 2023 14:48:07.8174 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4c011757-627f-4d61-a566-08daf25085aa X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT093.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4096 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The last_pg is wrong, it is actually the first page of the last scatterlist element. To get the last page of the last scatterlist element we have to add prv->length. So it is checking mergability against the wrong page, Further, a SG element is not guaranteed to end on a page boundary, so we have to check the sub page location also for merge eligibility. Fix the above by checking physical contiguity, compute the actual last page and then call pages_are_mergable(). Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device p= ages") Reported-by: Jason Gunthorpe Signed-off-by: Yishai Hadas Reviewed-by: Jens Axboe Reviewed-by: Logan Gunthorpe --- lib/scatterlist.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/lib/scatterlist.c b/lib/scatterlist.c index f72aa50c6654..2377917893e7 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -470,22 +470,29 @@ int sg_alloc_append_table_from_pages(struct sg_append= _table *sgt_append, return -EOPNOTSUPP; =20 if (sgt_append->prv) { + unsigned long paddr =3D + (page_to_pfn(sg_page(sgt_append->prv)) * PAGE_SIZE + + sgt_append->prv->offset + sgt_append->prv->length) / + PAGE_SIZE; + if (WARN_ON(offset)) return -EINVAL; =20 /* Merge contiguous pages into the last SG */ prv_len =3D sgt_append->prv->length; - last_pg =3D sg_page(sgt_append->prv); - while (n_pages && pages_are_mergeable(pages[0], last_pg)) { - if (sgt_append->prv->length + PAGE_SIZE > max_segment) - break; - sgt_append->prv->length +=3D PAGE_SIZE; - last_pg =3D pages[0]; - pages++; - n_pages--; + if (page_to_pfn(pages[0]) =3D=3D paddr) { + last_pg =3D pfn_to_page(paddr - PAGE_SIZE); + while (n_pages && pages_are_mergeable(pages[0], last_pg)) { + if (sgt_append->prv->length + PAGE_SIZE > max_segment) + break; + sgt_append->prv->length +=3D PAGE_SIZE; + last_pg =3D pages[0]; + pages++; + n_pages--; + } + if (!n_pages) + goto out; } - if (!n_pages) - goto out; } =20 /* compute number of contiguous chunks */ --=20 2.18.1