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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 86141C35247 for ; Tue, 4 Feb 2020 23:37:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59D0E214AF for ; Tue, 4 Feb 2020 23:37:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="BcTXvoSg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727678AbgBDXhq (ORCPT ); Tue, 4 Feb 2020 18:37:46 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:51668 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727461AbgBDXhq (ORCPT ); Tue, 4 Feb 2020 18:37:46 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 014NXSju080207; Tue, 4 Feb 2020 23:37:34 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : subject : from : to : cc : date : in-reply-to : references : content-type : mime-version : content-transfer-encoding; s=corp-2019-08-05; bh=c89x4AYik3CY1dqU0wAVrxhhMg8pCILWGeQVUweuj80=; b=BcTXvoSgSVY0m9Zzdg/u2oQVSbOgPMijyGuj5/cPHMH6Wq2/zuOk5s0RrK1cL4vs3yYn +/090kIgsQcfCSdXLEAaJHXHlnZfYAbAZxeZqAKkO3sHqD08O2IMIgFKXBE6RayLRd7B gHdhmQCa11ujg63Mf5NH/OLsT6jCDMBY6U8w3KVoCrgsCqE94Xc7ciGudP60fbEanmnv xTRsaVl/ZVuhbMIFU6ByYia5a0dwZ8KyuPURF9PDVeGYhqHFE1hDFBBpymD0XhJeeJ59 0uiNq5Fm98VmSMb9T7VY5oi3IAU/39pY63LAt3W7l1xZaCVMvIqWmWtLYGBB5xTMlkbf Eg== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2xyhkfg614-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 04 Feb 2020 23:37:34 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 014NXQKX177891; Tue, 4 Feb 2020 23:37:34 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 2xyhmqubup-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 04 Feb 2020 23:37:34 +0000 Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 014NbWoi010973; Tue, 4 Feb 2020 23:37:32 GMT Received: from dhcp-10-154-157-166.vpn.oracle.com (/10.154.157.166) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 04 Feb 2020 15:37:32 -0800 Message-ID: <787a40adec270a7c72ab1862f4fe1ada088818f1.camel@oracle.com> Subject: Re: [PATCH] mm: always consider THP when adjusting min_free_kbytes From: Khalid Aziz To: Mike Kravetz , David Rientjes Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Song Liu , "Kirill A.Shutemov" , Mel Gorman , Vlastimil Babka , Andrew Morton Date: Tue, 04 Feb 2020 16:37:30 -0700 In-Reply-To: <8cc18928-0b52-7c2e-fbc6-5952eb9b06ab@oracle.com> References: <20200204194156.61672-1-mike.kravetz@oracle.com> <8cc18928-0b52-7c2e-fbc6-5952eb9b06ab@oracle.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9521 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=11 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-2001150001 definitions=main-2002040160 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9521 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=11 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-2001150001 definitions=main-2002040160 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2020-02-04 at 13:42 -0800, Mike Kravetz wrote: > On 2/4/20 12:33 PM, David Rientjes wrote: > > > > So it looks like this is fixing an obvious correctness issue but > > also now > > requires users to rewrite the sysctl if they want to decrease the > > min > > watermark. > > Moving the call to khugepaged_adjust_min_free_kbytes as described > above > would avoid the THP adjustment unless we were going to overwrite the > user defined value. Now, I am not sure overwriting the user defined > value > as is done today is actually the correct thing to do. > > Thoughts? > Perhaps we should never overwrite a user defined value? We might need to override user defined value if it is too low but overriding it silently is not quite right. We should print a warning at least. On the other hand, a user setting min_free_kbytes should know what they are doing and if they set it too low, they have been warned in the sysctl documentation. I would say we never override user defined value but print a warning if the value is too low and kernel would have adjusted it if it were not for the user defined value. -- Khalid