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Mon, 24 Aug 2026 20:20:22 +0000 Date: Mon, 24 Aug 2026 13:20:20 -0700 From: "Luck, Tony" To: Breno Leitao CC: Borislav Petkov , Thomas Gleixner , "Ingo Molnar" , Dave Hansen , , "H. Peter Anvin" , Jonathan Corbet , Shuah Khan , Randy Dunlap , , , , Subject: Re: [PATCH 2/2] x86/mce: Add mce=panic_on_ce_count to panic on a corrected error flood Message-ID: References: <20260821-mce-panic-on-storm-v1-0-7a465c708d82@debian.org> <20260821-mce-panic-on-storm-v1-2-7a465c708d82@debian.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SJ0PR05CA0156.namprd05.prod.outlook.com (2603:10b6:a03:339::11) To SJ1PR11MB6083.namprd11.prod.outlook.com (2603:10b6:a03:48a::9) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PR11MB6083:EE_|IA1PR11MB6491:EE_ X-MS-Office365-Filtering-Correlation-Id: fa8ad605-c3f5-413a-8f8e-08df021d1fde X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|23010399003|376014|7416014|1800799024|10067099003|3023799007|18002099003|22082099003|4143699003|11063799006|56012099006; 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I don't think this needs to be fixed, but you should be aware and > > > perhaps document the shared bank details. > > > > > > This won't count accurately for banks that are shared by multiple logical > > > CPUs (you've inherited this from the storm detection code that introduces > > > this problem). > > > > > > E.g. a machine check bank reporting L2 errors is shared by both logical CPUs > > > on a core on P-core systems, and by all cores on a module on E-core systems. > > > > Good point, thanks. I had not thought about the shared bank case. > > > > I will document it in v2, roughly like this under panic_on_ce_count= > > in kernel-parameters.txt: > > > > The count is kept per CPU and per bank. A bank shared by > > several logical CPUs -- an L2 bank is shared by the SMT > > siblings, for instance -- has its errors split across those > > CPUs. > > > > plus a line in the changelog noting that the count inherits the > > granularity of the storm tracking. Thus, there may be > > more errors logged than you expect before your panic fires. Would it be better? > > Yes. Documentation like this in the commit, and under Documentation/* > gives fair notice to users. > > > One question while I am here: is the approach itself something you are > > willing to take, or, just a just send patch [1/2]? > > Boris is the maintainer here. So he has the final decision. My > opinion is that this is a bit niche for the kernel. Maybe this > could be handled by some user agent (mcelog? rasdaemon?) to > raise awareness to system operators about high rates of corrected > errors. I chatted with someone internally. They'd be very interested in being able to see these running counts via some /sys files. Perhaps your use case would be better for that too? Rather than: "Everything is fine" ... "Everything is fine" ... "Everything is fine" ... "Everything is fine" ... "Count exceeded, PANIC!" > > Thanks for the review, > > --breno > > -Tony -Tony >