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Tue, 30 Jun 2026 12:24:57 -0700 Date: Tue, 30 Jun 2026 12:24:58 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: Pranjal Shrivastava , Mostafa Saleh , , , , , , , , , , , , Subject: Re: [PATCH rc v7 0/7] iommu/arm-smmu-v3: Fix device crash on kdump kernel Message-ID: References: <20260630190819.GG7481@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260630190819.GG7481@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PEPF0000000F:EE_|CY8PR12MB8267:EE_ X-MS-Office365-Filtering-Correlation-Id: a959c263-d134-44dd-9525-08ded6dd50a7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|7416014|82310400026|36860700016|1800799024|13003099007|18002099003|22082099003|20046099003|11063799006|56012099006|4143699003|6133799003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 3tD1AUINm11GzvrVykByft1KRUCP5J8ZBIF955aVUb+wD1JpkM6riO29GmIQCiyRa1q2OyKVP4aVNI95if8GRALIR55Xbq+ElmZf0VrfSPhtAbtjDVX7KMP3Dw0xRwfkOFEeyo9f40QBHT+KxkxEktbRgONPXQ3RfcfrwDj1ysJJRbRuH+v8UhNo1GCVFeEETgN30uy/JLBBPU3jDGhpp/5u5rbzTU2WeZ5d5lXgvp+O88BI7C6f+cISVIyiCUgi2ACbKgQTNOkcDEfhqX1mRr5KpLY4XXazlp7o/TIS0L9dHimIDXXiGTU/RKk6li0TXcKigaKF42J8bLCS4YbFw4HTve7IZRvRcqcB3hafk5Evtpef5jztPGZacuEdGfSWNcvNSlWbwXc+dG9KGQy+IVFLSGP/w67sEeDxU1gY56kx456DbaxOFPeA95uH+ShT X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jun 2026 19:25:16.0914 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a959c263-d134-44dd-9525-08ded6dd50a7 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CH3PEPF0000000F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB8267 On Tue, Jun 30, 2026 at 04:08:19PM -0300, Jason Gunthorpe wrote: > On Tue, Jun 30, 2026 at 06:30:41PM +0000, Pranjal Shrivastava wrote: > > > As I mentioned above in the previous > > > reply I am not sure I understand what situation leads into this, when > > > does a device trigger SError to the system vs when not which is observed > > > as an event in that case. > > > > Ack. I see what you mean now.. How does a DMA fault raise an SError? > > As I gave an example to Robin if the unhandled failure escalates into > RAS emergency unplugging CXL memory then the system is going to > explode when kdump touches that CXL memory as part of the dumping. It > is not quite so simple that a DMA abort is triggering SError. Here is link to that email: https://lore.kernel.org/all/20260416172005.GB761338@nvidia.com/ > I don't know exactly the sequence of events that lead up to the kdump > kernel crashing (I imagine it is hard to debug that one), but it is > something related to the new kernel not participating in the RAS and > the RAS flow escalating to something fatal. Here is the original bug report: - kernel boots into a crash kernel - crash kernel hits OOM do to insufficient reserved memory and panics - PCIe errors are observed during this failure flow Thanks Nicolin