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=-3.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_AGENT_GIT 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 E641DC43218 for ; Fri, 26 Apr 2019 16:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6D3E212F5 for ; Fri, 26 Apr 2019 16:11:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="IU3RNsgH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726524AbfDZQLB (ORCPT ); Fri, 26 Apr 2019 12:11:01 -0400 Received: from mail-it1-f195.google.com ([209.85.166.195]:36056 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726039AbfDZQLA (ORCPT ); Fri, 26 Apr 2019 12:11:00 -0400 Received: by mail-it1-f195.google.com with SMTP id y10so6637886itc.1 for ; Fri, 26 Apr 2019 09:11:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digitalocean.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to; bh=vqL+eBAoqQcyj0QL9U9OxlX66XIdQVKeIzxdtdKg2E0=; b=IU3RNsgHvt3vxeftyVcqCm38QfUQxUH+AJdua4VTJ65+wEUndmp782ljsxl6Yp+lf3 WlvynlmNcHpUPutFoIf17PgenXM9Zzo8ZTaL5W9G5qMKVynoKe3eIm473YVP3QY6dheK Y+bxsm0g6lSXVk6tHhstWjllTNdneFtjnq9r8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to; bh=vqL+eBAoqQcyj0QL9U9OxlX66XIdQVKeIzxdtdKg2E0=; b=har6x7ShJeYitTBg3cv4H/oCuftLN1Z/gFCSicA2lKFHdiO/RZBn0JHEhH34wj39h1 O5k3ZkPR9qV9TbHo8SwnFGv7xKQs+EO5vxyRsT4zHNAu97p6U0QYxDpG/1Vz+nfP22Iu SzhtdtsAkAMHNnR81wav9lb8aOlU0dQWnnoMeGmNhVndwUCST/GfGPgcCzzJ01AZuDK5 IRftZqNDU0WZ3yzM1VzvR4KLU22pGY5ftblWoGpyusJd3joYkEdMA7aSlN45aYK9C+FA sEIAbRMWY5lsyqhw7gphLmiGp0433RDyjUQUTUwv8TiwZVUJ7+eLbPOXEOL+novWM4ak kb4w== X-Gm-Message-State: APjAAAUPhjmici2IaW3IHLD+ov75uHPlwSihJQT/YaX5ogvQrrTkAzZL jE6xoo/m0WdeuOQhy4RFQZqKnQ== X-Google-Smtp-Source: APXvYqwj+T/T4LXQpOygpMP25cLTdAsJ3yO2oCDuet/otob1iG6o9f535+K+R3mtQI7sbmypcOJ3FA== X-Received: by 2002:a24:5784:: with SMTP id u126mr520742ita.128.1556295060015; Fri, 26 Apr 2019 09:11:00 -0700 (PDT) Received: from swap-tester ([178.128.225.14]) by smtp.gmail.com with ESMTPSA id l188sm12121150itb.24.2019.04.26.09.10.58 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 26 Apr 2019 09:10:59 -0700 (PDT) From: Vineeth Remanan Pillai To: Peter Zijlstra Cc: Vineeth Remanan Pillai , Nishanth Aravamudan , Julien Desfossez , Aubrey Li , Tim Chen , mingo@kernel.org, tglx@linutronix.de, pjt@google.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, subhra.mazumdar@oracle.com, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Aaron Lu , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , Phil Auld Subject: Re: [RFC PATCH v2 09/17] sched: Introduce sched_class::pick_task() Date: Fri, 26 Apr 2019 16:10:56 +0000 Message-Id: <20190426161056.4624-1-vpillai@digitalocean.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190426140209.GA2623@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > I didn't get around to reading the original discussion here, but how can > that possibly be? > > I can see !se, in that case curr is still selected. > > I can also see !curr, in that case curr is put. > > But I cannot see !se && !curr, per the above check we know > cfs_rq->nr_running != 0, so there must be a cfs task to find. This means > either curr or se must exist. This fix was suggested as a quick fix for a crash seen in v1. But I agree with you that this should be a bug if it happens and should be investigated. I have tried in v2 and can no longer reproduce the crash. Will remove the check in v3. Thanks