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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 33C3BC433DF for ; Tue, 2 Jun 2020 04:02:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F10CE20870 for ; Tue, 2 Jun 2020 04:02:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="jRp6tZ1+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726370AbgFBEC1 (ORCPT ); Tue, 2 Jun 2020 00:02:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726110AbgFBECZ (ORCPT ); Tue, 2 Jun 2020 00:02:25 -0400 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CB37C061A0E for ; Mon, 1 Jun 2020 21:02:25 -0700 (PDT) Received: by mail-qk1-x741.google.com with SMTP id v79so11275584qkb.10 for ; Mon, 01 Jun 2020 21:02:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=content-transfer-encoding:from:mime-version:date:subject:message-id :cc:to; bh=GMRYb8RFRRtwlzEMKi7MT1e7/aWKzB1rdupbFt9KNtw=; b=jRp6tZ1+10Pww1SnEP6YZSCKZrfK4Bb0tu4iuVM86ZsK77NQneS5pHXcnc8qqfJM4z CqtON3na4dFSWJARhtLOlhCx6w/72Gh8GW6rc/fdQf497drxJo7L55uuddB4lV+YZnaJ RUyuIxwhycaJ1fHxSMCSCQtsHeka6H8dpkN1S1opSmV2dLmnKVpvy4uT8hQAfHmqQtKD 3fcmTOOwczWMkM6M0jMaw/a8o33ZCPi7ZmfsLXSTLM/+xP7VcD6dnECwnV2WX1vL0G6+ NHfZYMz90q7jajQ/rTJDlhR1kLzGINO0pVCp8QGU+naPWdgagXGOM/iXMXmLZNdp6mvD yXhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version:date :subject:message-id:cc:to; bh=GMRYb8RFRRtwlzEMKi7MT1e7/aWKzB1rdupbFt9KNtw=; b=C4WyamebI8BXb1+8lwEGo0F1b30dh0lb/bnlVMBF/09p8/ax0pD9L0dIOelL3EoaBc qUXnyS8LVVw/cA1Fg/QcmAgavS5humgQLCQewE+ofhoUDQzFlLv3vWf71cBBuwEZDafE Q4JteIduNfgYqML57yz0zTZSSQY+P0J4Y6snYv9OmAybwNe10qqyBcdl7KDgl06cv6W6 Wv6qzhXqa1a+r74JMhxLF7fW8O91zLN7b055OOzYdKTyBs6fjqlmHdI/2QjLjoWuffD7 NFSJ6D+RTx+14Cr0KG6rpzVoW+5Xag3Qzqplj+2As/IHyecWRdb+7c3kNBDstlmy8IsT b8ug== X-Gm-Message-State: AOAM531HuD8M7OYv6l6e1eFCmTNxlrJ+ZrfoqhgaMYfappCdA9QMZH/G OV/c/IOxHaEKundz4S6eQGUlPQ== X-Google-Smtp-Source: ABdhPJy/MJO7Qoq7doJPnEHbUf6iHSLmfO7PH+CZYb7yDFBioDv+2RchlNaB21JisJNsSLxwHGUMUA== X-Received: by 2002:a37:8803:: with SMTP id k3mr16727466qkd.311.1591070543919; Mon, 01 Jun 2020 21:02:23 -0700 (PDT) Received: from [192.168.1.183] (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id y185sm1071027qkd.83.2020.06.01.21.02.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 01 Jun 2020 21:02:23 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Qian Cai Mime-Version: 1.0 (1.0) Date: Tue, 2 Jun 2020 00:02:22 -0400 Subject: Re: [PATCH v4 3/4] mm/util.c: remove the VM_WARN_ONCE for vm_committed_as underflow check Message-Id: Cc: Andrew Morton , Michal Hocko , Johannes Weiner , Matthew Wilcox , Mel Gorman , Kees Cook , andi.kleen@intel.com, tim.c.chen@intel.com, dave.hansen@intel.com, ying.huang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Konstantin Khlebnikov To: Feng Tang X-Mailer: iPhone Mail (17E262) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jun 1, 2020, at 11:37 PM, Feng Tang wrote: >=20 > I re-run the same benchmark with v5.7 and 5.7+remove_warning kernels, > the overall performance change is trivial (which is expected) >=20 > 1330147 +0.1% 1331032 will-it-scale.72.processes >=20 > But the perf stats of "self" shows big change for __vm_enough_memory()=20 >=20 > 0.27 -0.3 0.00 pp.self.__vm_enough_memory >=20 > I post the full compare result in the end. I don=E2=80=99t really see what that means exactly, but I suppose the warnin= g is there for so long and no one seems notice much trouble (or benefit) bec= ause of it, so I think you will probably need to come up with a proper justi= fication to explain why it is a trouble now, and how your patchset suddenly s= tart to trigger the warning as well as why it is no better way but to suffer= this debuggability regression (probably tiny but still).=