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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2841C43387 for ; Fri, 28 Dec 2018 02:02:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 869A32148E for ; Fri, 28 Dec 2018 02:02:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545962570; bh=UuHRVtE5TOF51cQ882HbjSfzxjsKe2O1mPugL3Z0ip0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=tg1l+Y8GJgrKeOasma2y9YS+Yn7Ra1g1gGEvsjBHNLXWak2fRpnGE/UFQZxUQYbCx WYwojncnn4/Gt7I01mUiUpCaT474mgbE3Ekf8IDRCMAQ3hXhv42o66erqET16gG0FP Epjf+G1i4Dd8vQ2ABQSjOYe87PWOzSmIILCQF4Xg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726765AbeL1CCt (ORCPT ); Thu, 27 Dec 2018 21:02:49 -0500 Received: from mail-yw1-f67.google.com ([209.85.161.67]:33259 "EHLO mail-yw1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725910AbeL1CCt (ORCPT ); Thu, 27 Dec 2018 21:02:49 -0500 Received: by mail-yw1-f67.google.com with SMTP id p65so6775912ywe.0 for ; Thu, 27 Dec 2018 18:02:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=qFOK9QSGto8EOXWIC+uhgBoTwFjpX9AyK9r/zP53OZI=; b=XgvLc9Ka4D7a48teev/Fi6Zs2+oLiMTziRxaPEpRbmX6vyTOSLd1RGdTOO24nOakSS cUPGrSr0PG9fz0o4Czv2iQmP5ZCJ1ULwWHHQI4x92EL7gYK0fmgw/pTqmomyrAO30+oc hPxkuuDszDPQQgg9Mvyh7mHDIj/w4cFXizPaSXTbXVraqkDJm9n3RUh5sWQfvOOo42MA Qqx/iCj60LD94oZGTrATGbrzOTOHdZeevpcm1MLlTt6Sa7IbKxQyNgRGB1NT7gBh7/ck ATd0fd+3AXoLO855hg2xRKyJcxzt3e5rHHWxPdVMIT81dflOK+ND0bsYMbiHRmvh6bMd fSZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=qFOK9QSGto8EOXWIC+uhgBoTwFjpX9AyK9r/zP53OZI=; b=Z/uxTknAgUB0/2q6jwHSz8S1xERtPf7mHpxVQJTbMKAb1Xwn95oBAmYg8uGmst5Ms+ CAh0zdAcVNI2HqqTQyvCNRw2bROYbvYebv2EwyR20TlJ/EX8MN6nPCsdlAER3yVS72VK +QOUNdGbi31qSDaPng7CZU4eigBDX8qpYC7x87NeORnV5Kgd7M1cL15Kp195o6IWz4gB DpJI/m0tCOPBMFQ9YuP4DXUsK0YhR3OO+v0A9XjLPcCQPjlcAuRhML+PKUSOilwAuNst bW6iAHuIJWb1hG7UqUCRbYcl2d3cZQoS7M2A4Us4aulG8ZR3y/PBuaRoa+RqVMEUW5JV e4Dw== X-Gm-Message-State: AA+aEWY+yU0f8+1QbaiSTaXukv0WR/BaCfjenTt/2NSpQm4qcEAuaZlO dmhteOUmPdhjh3ELFjWDt28= X-Google-Smtp-Source: AFSGD/VeDqxm7wZ8X+rI6UI5HtGKf0rckZ/BI15oSaoKgxsr1RzRyTSu1QdiG2quEGtiilwQHVbE6g== X-Received: by 2002:a0d:e6ca:: with SMTP id p193mr25445891ywe.217.1545962566763; Thu, 27 Dec 2018 18:02:46 -0800 (PST) Received: from localhost ([2620:10d:c091:180::1:7729]) by smtp.gmail.com with ESMTPSA id m126sm14259666ywd.39.2018.12.27.18.02.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Dec 2018 18:02:45 -0800 (PST) Date: Thu, 27 Dec 2018 18:02:43 -0800 From: Tejun Heo To: Linus Torvalds Cc: Vincent Guittot , Sargun Dhillon , Xie XiuQi , Ingo Molnar , Peter Zijlstra , xiezhipeng1@huawei.com, huawei.libin@huawei.com, linux-kernel , Dmitry Adamushko , Rik van Riel Subject: Re: [PATCH] sched: fix infinity loop in update_blocked_averages Message-ID: <20181228020243.GH2509588@devbig004.ftw2.facebook.com> References: <1545879866-27809-1-git-send-email-xiexiuqi@huawei.com> <20181227102107.GA21156@linaro.org> <20181228011524.GF2509588@devbig004.ftw2.facebook.com> <20181228015352.GG2509588@devbig004.ftw2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181228015352.GG2509588@devbig004.ftw2.facebook.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 27, 2018 at 05:53:52PM -0800, Tejun Heo wrote: > Vincent knows that part way better than me but I think the safest way > would be doing the optimization removal iff tmp_alone_branch is > already pointing to leaf_cfs_rq_list. IIUC, it's pointing to > something else only while a branch is being built and deferring > optimization removal by an avg update cycle isn't gonna make any > difference anyway. So, something like the following. Xie, can you see whether the following patch resolves the problem? diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d1907506318a..88b9118b5191 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7698,7 +7698,8 @@ static void update_blocked_averages(int cpu) * There can be a lot of idle CPU cgroups. Don't let fully * decayed cfs_rqs linger on the list. */ - if (cfs_rq_is_decayed(cfs_rq)) + if (cfs_rq_is_decayed(cfs_rq) && + rq->tmp_alone_branch == &rq->leaf_cfs_rq_list) list_del_leaf_cfs_rq(cfs_rq); /* Don't need periodic decay once load/util_avg are null */