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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS2PEPF00003439.mail.protection.outlook.com (10.167.18.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8511.15 via Frontend Transport; Tue, 4 Mar 2025 05:22:44 +0000 Received: from [10.136.44.144] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Mon, 3 Mar 2025 23:22:40 -0600 Message-ID: <0f4de435-a48e-4c4b-9c56-b7c4dc1b96cf@amd.com> Date: Tue, 4 Mar 2025 10:52:37 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full From: K Prateek Nayak To: Mateusz Guzik CC: "Sapkal, Swapnil" , Oleg Nesterov , Manfred Spraul , Linus Torvalds , Christian Brauner , David Howells , WangYuli , , , "Shenoy, Gautham Ranjal" , , References: <20250227211229.GD25639@redhat.com> <06ae9c0e-ba5c-4f25-a9b9-a34f3290f3fe@amd.com> <20250228143049.GA17761@redhat.com> <20250228163347.GB17761@redhat.com> <03a1f4af-47e0-459d-b2bf-9f65536fc2ab@amd.com> <741fe214-d534-4484-9cf3-122aabe6281e@amd.com> <3jnnhipk2at3f7r23qb7fvznqg6dqw4rfrhajc7h6j2nu7twi2@wc3g5sdlfewt> Content-Language: en-US In-Reply-To: Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Mar 2025 05:22:44.1796 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 20c3634e-fe31-4854-62a4-08dd5adc97cf X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF00003439.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6473 Hello Mateusz, On 3/4/2025 12:02 AM, K Prateek Nayak wrote: > Hello Mateusz, > > On 3/3/2025 11:24 PM, Mateusz Guzik wrote: >> Can you guys try out the patch below? >> >> It changes things up so that there is no need to read 2 different vars. >> >> It is not the final version and I don't claim to be able to fully >> justify the thing at the moment either, but I would like to know if it >> fixes the problem. > > Happy to help! We've queued the below patch for an overnight run, will > report back once it is done. Hackbench has been running for a few thousand iteration now without experiencing any hangs yet with your changes. > > Full disclaimer: We're testing on top of commit aaec5a95d596 > ("pipe_read: don't wake up the writer if the pipe is still full") where the > issue is more reproducible. I've replaced the VFS_BUG_ON() with a plain > BUG_ON() based on [1] since v6.14-rc1 did not include the CONFIG_DEBUG_VFS > bits. Hope that is alright. > > [1] https://lore.kernel.org/lkml/20250209185523.745956-2-mjguzik@gmail.com/ > > /off to get some shut eyes/ > -- Thanks and Regards, Prateek