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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 57386C433E6 for ; Tue, 21 Jul 2020 11:25:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30F422064C for ; Tue, 21 Jul 2020 11:25:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595330735; bh=7A5kQtDDM/GtMDMbKqd8YEx9XpKSoyPCfQAMnX1dy4U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=IMGbaoizbxNJ0pblUy+fT41UmaxRFcyJ/0sG+Wo8POz83Qzmxu/gbjV2TF4SllN8G l4+uGwxMKeRLRFe6wXMTxxsd75ddAV7uBB7RbRebxPyb1Zd39fBAvk5d5nN7rmLH5O ombzIuJIi/R0hscguxuJSQArgWBc2UKBKi0Xgm4w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729695AbgGULZd (ORCPT ); Tue, 21 Jul 2020 07:25:33 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:46008 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728108AbgGULZd (ORCPT ); Tue, 21 Jul 2020 07:25:33 -0400 Received: by mail-wr1-f66.google.com with SMTP id s10so20773972wrw.12 for ; Tue, 21 Jul 2020 04:25:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=eDTdOZ1dDPKD1UqSkexaZR5dMf1fmObppvOA9WWtcgo=; b=oyiOxy2/AXmOtGdpulNKvZqs63SrUho3mMqn10p/Rg8TxTq2vsHPwHjOaVGGgzboxq ccmU6ET2WiVAmiD8N+fMdgmtLg21QxmtN0bCE83cSATqOVo6KhcSU4X835UBVdT4GaSe xooh8ZRzKG1CqxJx519zEU+BPg1/R3UDEqiK5Fc+G1NKz0OUzytwM/QmxhibrM38s9PF 5KexqlnBLiNCI3G8xWaGZM3XKPEK6J9GmMwnkKY+zluvmmNfBl6oz7+xTysz/T7u/s06 kfykmNcuyQJVkf5eyvoZNft86cS7LjTrEfE7BUTw0t5YYwIekZDhtlPpoGmvHWO9Tlhk dVBA== X-Gm-Message-State: AOAM5338e80JIIqfMWMtgQ/YdxqA2ik7i4X2XPoXolX2OzpOlgUGPoLe Cl3xhKquGpCmkccy24Vk3WQ= X-Google-Smtp-Source: ABdhPJzZKaTi9QRRHmX+Uo51vDunXQdue9WmRqUSRKPrkIu061TGYiIPW/mozoV1jdvTv2eoWOEt+Q== X-Received: by 2002:a5d:4b0c:: with SMTP id v12mr17163309wrq.199.1595330731618; Tue, 21 Jul 2020 04:25:31 -0700 (PDT) Received: from localhost (ip-37-188-169-187.eurotel.cz. [37.188.169.187]) by smtp.gmail.com with ESMTPSA id o21sm3068116wmh.18.2020.07.21.04.25.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Jul 2020 04:25:30 -0700 (PDT) Date: Tue, 21 Jul 2020 13:25:29 +0200 From: Michal Hocko To: Qian Cai Cc: linux-mm@kvack.org, LKML , Andrew Morton , Linus Torvalds , Tim Chen Subject: Re: [RFC PATCH] mm: silence soft lockups from unlock_page Message-ID: <20200721112529.GJ4061@dhcp22.suse.cz> References: <20200721063258.17140-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 21-07-20 07:10:14, Qian Cai wrote: > > > > On Jul 21, 2020, at 2:33 AM, Michal Hocko wrote: > > > > on a large ppc machine. The very likely cause is a suboptimal > > configuration when systed-udev spawns way too many workders to bring the > > system up. > > This is strange. The problem description is missing quite a few > important details. For example, what systems exactly are those? How > many CPUs, memory and NUMA nodes were you talking about? Are these really important? I believe I can dig that out from the bug report but I didn't really consider that important enough. > Which kernel version was it reported? It is a SLES 4.12 based kernel with the said commit backported. The page lock internals are thus in line with the upstream kernel. > How many workers from systemd-udev was “misconfigured”? I do not know that information. I believe that it used whatever systemd comes with as a default. And that can be a lot. Do you have any actual feedback to the patch? -- Michal Hocko SUSE Labs