From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31B67C433F5 for ; Mon, 16 May 2022 18:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344725AbiEPSWY (ORCPT ); Mon, 16 May 2022 14:22:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244371AbiEPSWM (ORCPT ); Mon, 16 May 2022 14:22:12 -0400 Received: from mail-il1-x134.google.com (mail-il1-x134.google.com [IPv6:2607:f8b0:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C06872BB02 for ; Mon, 16 May 2022 11:22:10 -0700 (PDT) Received: by mail-il1-x134.google.com with SMTP id d3so11061717ilr.10 for ; Mon, 16 May 2022 11:22:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=fi2MKK4RDnx6306yvIj3WqOA9+3aIysOXF+Rc+RJb4Y=; b=ZoeYipp1srp2zffS6xSdw3auO/PUsqr9RF6aFDmflEnta+cN9h3QQekvih8nXjtLzx denBn/B1SfVOfEOGy2MF80u8pStM64jj/Q2zsXN+0DFTuPMdMb/kksBYYo5pDGgM6Yt+ fQrwdiKbkUsAUy4DQF5f5RGSkh1OWCthVya+Z8j8X4Bt7hdKTcT7PU0zWixT1OJgcek/ srWG6vzSTBHbi3Je60NibFukSh1mtN5de+TrSHi34uZCkJcKJYnVvJECuvwSJucjknSV D6xDfmCN71FptFkL1m+92AWgmDlknvKgLHAtCLgI4FND7h1wZvCv4Q/JcGlY1n3RjpjN 00JA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=fi2MKK4RDnx6306yvIj3WqOA9+3aIysOXF+Rc+RJb4Y=; b=TcBUAb8Z6x5C3QK0jFV84K+ydaAQjUpfMeFIv37IYpb5e5NA2UVpasRTHIYlDvnVY0 +LXvtzArnNvLzGBNYNzGCIt/gKTyDSlReICgMOh8o/Q/zhecAF6Xwl2VHrbMgoPMxD7y FWJMGUTXT0MHGxInEJsd3WDfcpz3GHeVibW+/B1FPtILx5bo7DSSDvXryVWSdNZzubKK TQwodK8yDwl8VCda2pLyFHAwZBm7UZAyhmpOnReAiIrIQshAw0oEF2j/ELGjd+wneWA7 TQvtRsH3Shk50DnOGG6fcpC7xSm5HXbdkIvJjkrMum6iz5O3xM68yVVQrbenKgUOVfM/ grdQ== X-Gm-Message-State: AOAM532s9XFoPJjdbvbFn8wofRPdBRP5wx1YnbG8u1kHVtFyA819j5Ms c4ZneXCRbfKq5KrPpaVUiloDFY55Qz3OjA== X-Google-Smtp-Source: ABdhPJwu+uko3W1bDT97qFkqQc86IbLg5bTX+TVEm+Bg5/uK411UrX/M11NqCONlxy6V9sq7qROTPA== X-Received: by 2002:a05:6e02:1c27:b0:2cf:6de9:5342 with SMTP id m7-20020a056e021c2700b002cf6de95342mr9584457ilh.176.1652725329933; Mon, 16 May 2022 11:22:09 -0700 (PDT) Received: from [192.168.1.172] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id l44-20020a026a2c000000b0032b3a7817d3sm2964148jac.151.2022.05.16.11.22.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 May 2022 11:22:08 -0700 (PDT) Message-ID: Date: Mon, 16 May 2022 12:22:07 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [REGRESSION] lxc-stop hang on 5.17.x kernels Content-Language: en-US To: Thorsten Leemhuis , Daniel Harding , Pavel Begunkov Cc: regressions@lists.linux.dev, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Christian Brauner References: <7925e262-e0d4-6791-e43b-d37e9d693414@living180.net> <6ad38ecc-b2a9-f0e9-f7c7-f312a2763f97@kernel.dk> <371c01dd-258c-e428-7428-ff390b664752@kernel.dk> <2436d42c-85ca-d060-6508-350c769804f1@gmail.com> <12a57dd9-4423-a13d-559b-2b1dd2fb0ef3@living180.net> <897dc597-fc0a-34ec-84b8-7e1c4901e0fc@leemhuis.info> <41c86189-0d1f-60f0-ca8e-f80b3ccf5130@gmail.com> <3fc08243-f9e0-9cec-4207-883c55ccff78@living180.net> <13028ff4-3565-f09e-818c-19e5f95fa60f@living180.net> <469e5a9b-c7e0-6365-c353-d831ff1c5071@leemhuis.info> From: Jens Axboe In-Reply-To: <469e5a9b-c7e0-6365-c353-d831ff1c5071@leemhuis.info> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/16/22 12:17 PM, Thorsten Leemhuis wrote: >>> Pavel, I had actually just started a draft email with the same theory >>> (although you stated it much more clearly than I could have). I'm >>> working on debugging the LXC side, but I'm pretty sure the issue is >>> due to LXC using blocking reads and getting stuck exactly as you >>> describe. If I can confirm this, I'll go ahead and mark this >>> regression as invalid and file an issue with LXC. Thanks for your help >>> and patience. >> >> Yes, it does appear that was the problem. The attach POC patch against >> LXC fixes the hang. The kernel is working as intended. >> >> #regzbot invalid: userspace programming error > > Hmmm, not sure if I like this. So yes, this might be a bug in LXC, but > afaics it's a bug that was exposed by kernel change in 5.17 (correct me > if I'm wrong!). The problem thus still qualifies as a kernel regression > that normally needs to be fixed, as can be seen my some of the quotes > from Linus in this file: > https://www.kernel.org/doc/html/latest/process/handling-regressions.html Sorry, but that's really BS in this particularly case. This could always have triggered, it's the way multishot works. Will we count eg timing changes as potential regressions, because an application relied on something there? That does not make it ABI. In general I agree with Linus on this, a change in behavior breaking something should be investigated and figured out (and reverted, if need be). This is not that. -- Jens Axboe I