From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CY3PR05CU001.outbound.protection.outlook.com (mail-westcentralusazon11013050.outbound.protection.outlook.com [40.93.201.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 760442DFF04 for ; Wed, 22 Apr 2026 12:07:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.201.50 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776859647; cv=fail; b=JjZOKy8J6IQ4JI0CMykFLMzBk2JGuQc7xxJVFIIV6JVip2W/qhCW4Px8KT/8P1hncr2Zb1tCa7d0LfXhQa/769KbRDblTcJj72LLikatINQ8bow6VyWx1FCj4xwHX999YR3NCzKr0tjudbmoK/Kylv49soS4w8VIHGBKGET7uBk= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776859647; c=relaxed/simple; bh=Cp/mK9z86FhUv2r33OFnRuWO1q29jMp/x79oLz69R6A=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=hBxkAiAIeqIG/qRaCcPc1Joi5uRmHMiWmRWvMr2lo7qwcT5eXFsAjz2E8C245SS9rWANaB7K9NAi2e7VJpsFUtmCm7XDPQOMA8anifNQ8QSMh32Hzkdv8Ai03KbOVftrSTVDVOHietNXJTiFy539PJ6NBjtFjXJFtfcBc7g227o= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=Y6PrLxOm; arc=fail smtp.client-ip=40.93.201.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="Y6PrLxOm" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=BlSz9/zZcqKiKQo/gMIC9l8x7ufFXpo/xtDVoxOd5ef/KnZ1sqTjyagoim7VX7WmAy7m3pz4147Twb4mKVDVfvjYpLwXwKDYsNLBHhYaRadWJ15Ne81LPFTYapXSNV0ecgQlMD8IVJp6wX3Mzcfp5l/pxBht8tS4iHoJGwp7hrvopOsbI1Jf6TSLM15QKizNj+LH87aueO/5vfmZZDAjtZw4CFTV6nGUUsVSsHAHjbfoQtV/mO+fFR9EA7TI826vNFDmTa+e+JS+wwJ8HS+mvuLqDliHLZ+qU8Z5SupivYiT+a9vO5jC/ujWR28/FX6VEyTzNNZp2iov1KTVP+8EqQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=+zwUj+MxAPzbcrZMPgEwWVb1SqvQByWtgAqItxjXHWQ=; b=vlk49/MkYEegXGaKd/IijkmxzNpeuMiwuM/4IoSeEOVmo6LPl4FCJ45RKjWdxoe0RvsulEzDQ43ewjCMah2UbSmR+4LcWXNCjmjpOTxlZkT981yXalLUgZ/QSs/kN2pRkF9iPO7rsAvcfs82uid0sijWVJq7I2EteOVOogTFaOGVSbnV/zf2m3UoPUjqdWfnPvO7eeLGqnPwIpJN559jkj/zE0IpvHRWFB4PsgdfP+YimyewSuW9rceKGRwPQe0w7JVec/94tG0ts67Bfq3BH7qqnbEISZc/+5MvMfC57E3kxGOktuH2WoMcsH/U0hRXnbiWDSxzarD6+XNWP0/d9Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=infradead.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=+zwUj+MxAPzbcrZMPgEwWVb1SqvQByWtgAqItxjXHWQ=; b=Y6PrLxOmMWBLLZzYwZkO1KUPGLlEQrN9xmUkhVgzLoSNFhZX4q8HEHA8xVehrqT3S5QtiNlMjHPN6r/8FvfWBWel6CGfSb7TUZuyGsdie6hsjsbgE+3gRcbVhYr5XrNsIDWn1iOlm5AX4+wMVebRx97oOaixRD4+rHxFjwIpu0Q= Received: from PH8PR02CA0002.namprd02.prod.outlook.com (2603:10b6:510:2d0::11) by SA3PR12MB8762.namprd12.prod.outlook.com (2603:10b6:806:31f::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.8; Wed, 22 Apr 2026 12:07:23 +0000 Received: from CY4PEPF0000E9DB.namprd05.prod.outlook.com (2603:10b6:510:2d0:cafe::1) by PH8PR02CA0002.outlook.office365.com (2603:10b6:510:2d0::11) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9791.48 via Frontend Transport; Wed, 22 Apr 2026 12:07:23 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CY4PEPF0000E9DB.mail.protection.outlook.com (10.167.241.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9846.18 via Frontend Transport; Wed, 22 Apr 2026 12:07:23 +0000 Received: from SATLEXMB04.amd.com (10.181.40.145) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.17; Wed, 22 Apr 2026 07:07:22 -0500 Received: from satlexmb08.amd.com (10.181.42.217) 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; Wed, 22 Apr 2026 07:07:22 -0500 Received: from [10.136.34.119] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Wed, 22 Apr 2026 07:07:19 -0500 Message-ID: Date: Wed, 22 Apr 2026 17:37:18 +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: Regression on linux-next (next-20260324 ) To: Peter Zijlstra , John Stultz CC: "Borah, Chaitanya Kumar" , , , "intel-gfx@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" , "Kurmi, Suresh Kumar" , "Saarinen, Jani" , References: <20260330195037.GW2872@noisy.programming.kicks-ass.net> <20260420130318.GD3102924@noisy.programming.kicks-ass.net> <20260421101521.GO3102624@noisy.programming.kicks-ass.net> <95651a71-1adf-45ba-83eb-5744bc6d4a52@amd.com> <20260421143752.GD1064669@noisy.programming.kicks-ass.net> <20260421205647.GL3126523@noisy.programming.kicks-ass.net> <20260422092335.GH3102924@noisy.programming.kicks-ass.net> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20260422092335.GH3102924@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Received-SPF: None (SATLEXMB04.amd.com: kprateek.nayak@amd.com does not designate permitted sender hosts) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000E9DB:EE_|SA3PR12MB8762:EE_ X-MS-Office365-Filtering-Correlation-Id: 47ed942a-554e-4e02-b7e7-08dea067b625 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|36860700016|82310400026|1800799024|56012099003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(36860700016)(82310400026)(1800799024)(56012099003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 4TrhnnT/jU2F9olBKcE9HXvCEyhHZ87UBi5sgMNWhZ7IDRO702K/37uOPKcPGPW2BR/GVtb+u61VwfhfDMNdp4tFUh3hSES2fpi1IdTg1CAsk7ogB+xJFtkQC1PYxBHosUx3K61obtRumiQ4cBUxNDJrfr5NJVnGA5p5fvw6Bd/ZuaWbIwVoNIwYnUXA+o89anNoD+4uCnY4bfeWDMekPL510AO/2DzIqXif48zUm13CIlZ/+TQw5AhMuHtzUGNuH5/ssqyWetay09ODOl7S+G1+9JLK1ynNff9PFXj/G1Z10llZwVt5gmLaH61hu+kPrH92xuO9SUlTk+s3PUGJNkLeLDW8FIGATUIiKxIM5OtoVFXpLAUGSoAvKz9rYtNJBfzL26BkTai6GcCdSA/EIoXD/1VGCV5NRgmdW5gmQIl28vgC+tasIxeKYKZ+KQMf X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2026 12:07:23.0344 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 47ed942a-554e-4e02-b7e7-08dea067b625 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000E9DB.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB8762 Hello Peter, On 4/22/2026 2:53 PM, Peter Zijlstra wrote: > On Tue, Apr 21, 2026 at 10:56:48PM +0200, Peter Zijlstra wrote: >> Excellent, I'll write it up tomorrow. > > How's this? It 'passes' the ww_mutex selftest thing in so far as that I > get the same: > > [ 2.312369] Beginning ww (wound) mutex selftests > [ 4.853240] stress (stress_inorder_work) failed with -35 > [ 9.379572] Beginning ww (die) mutex selftests > [ 16.435831] All ww mutex selftests passed > > before the offending commit and after this patch. Yup I see pretty much the same. I think 4k ww-mutexes being fought for by #CPUs threads with a short timeout doesn't sit too well with stress_inorder_work but it does make some forward progress until that timeout hits like before ;-) > > --- > Subject: Subject: locking/mutex: Fix ww_mutex wait_list operations > From: Peter Zijlstra > Date: Wed Apr 22 10:38:41 CEST 2026 > > Chaitanya and John reported commit 25500ba7e77c ("locking/mutex: Remove the > list_head from struct mutex") wrecked ww_mutex. > > Specifically there were 2 issues: > > - __ww_waiter_prev() had the termination condition wrong; it would terminate > when the previous entry was the first, which results in a truncated > iteration: W3, W2, (no W1). > > - __mutex_add_waiter(@pos != NULL), as used by __ww_waiter_add() / > __ww_mutex_add_waiter(); this inserts @waiter before @pos (which is what > list_add_tail() does). But this should then also update lock->first_waiter. > > Much thanks to Prateek for spotting the __mutex_add_waiter() issue! > > Fixes: 25500ba7e77c ("locking/mutex: Remove the list_head from struct mutex") > Reported-by: "Borah, Chaitanya Kumar" > Closes: https://lore.kernel.org/r/af005996-05e9-4336-8450-d14ca652ba5d%40intel.com > Reported-by: John Stultz > Closes: https://lore.kernel.org/r/CANDhNCq%3Doizzud3hH3oqGzTrcjB8OwGeineJ3mwZuGdDWG8fRQ%40mail.gmail.com > Debugged-by: K Prateek Nayak > Signed-off-by: Peter Zijlstra (Intel) Still runs as expected! Feel free to include: Tested-by: K Prateek Nayak -- Thanks and Regards, Prateek