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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA23FC433EF for ; Mon, 30 May 2022 09:37:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234819AbiE3JhM (ORCPT ); Mon, 30 May 2022 05:37:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233330AbiE3JhH (ORCPT ); Mon, 30 May 2022 05:37:07 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 623F37521E; Mon, 30 May 2022 02:37:05 -0700 (PDT) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24U7eIp4014435; Mon, 30 May 2022 09:35:23 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=ZYzW3+GXOL8I0AfUdLsg5MVY8XGCNIfi5dgvNuU6uaU=; b=aJRxENPLxPxtJPLPMpZbZB6ZMNv3yb0g75x/iaJw7LwXznLfzcFFd+VhsSYa4DDin1Og h3EtEuduOMNJdyWcPGf8Bp6j8HIvSzuOxy/3v6U/k2EZA3ai81b28DfbzQAvyLegWbh1 6JeeHGepvOgSmc7L30MoUcRt75rv2HhxbCLI6q4veiPA68Sc+ilz6QI6uDVuislGDiwl YeuRHaNHYRJKefnUIzx1TjXR7BhIi0QNPJjTPVc/RjJeQKBVl5otsnG/aMJgufq14x+Q SfzDBggiNkH6uIogm1bEat+ek9Ln35Wju1AiyyoOtoSpZv9Lk89aLEZ/3hCHMI9fbtzG Eg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gc21gt23u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 30 May 2022 09:35:22 +0000 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 24U8YFtI001535; Mon, 30 May 2022 09:35:21 GMT Received: from ppma01fra.de.ibm.com (46.49.7a9f.ip4.static.sl-reverse.com [159.122.73.70]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gc21gt22j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 30 May 2022 09:35:21 +0000 Received: from pps.filterd (ppma01fra.de.ibm.com [127.0.0.1]) by ppma01fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 24U9ZEW5005489; Mon, 30 May 2022 09:35:18 GMT Received: from b06avi18626390.portsmouth.uk.ibm.com (b06avi18626390.portsmouth.uk.ibm.com [9.149.26.192]) by ppma01fra.de.ibm.com with ESMTP id 3gbcakhu93-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 30 May 2022 09:35:18 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 24U9KsWE50921746 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 30 May 2022 09:20:54 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7A464A4054; Mon, 30 May 2022 09:35:14 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 55577A405B; Mon, 30 May 2022 09:35:11 +0000 (GMT) Received: from [9.171.2.176] (unknown [9.171.2.176]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 30 May 2022 09:35:11 +0000 (GMT) Message-ID: <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> Date: Mon, 30 May 2022 11:35:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared memory types Content-Language: en-US To: Heiko Carstens , Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Will Deacon , Matt Turner , linux-s390@vger.kernel.org, Andrew Morton , Brian Cain , Borislav Petkov , linux-alpha@vger.kernel.org, Alistair Popple , Jonas Bonn , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, Michael Ellerman , Stefan Kristiansson , linux-snps-arc@lists.infradead.org, Vineet Gupta , Vasily Gorbik , Vlastimil Babka , Ivan Kokshaysky , Rich Felker , sparclinux@vger.kernel.org, Russell King , David Hildenbrand , Benjamin Herrenschmidt , Nicholas Piggin , "James E . J . Bottomley" , linux-xtensa@linux-xtensa.org, linux-sh@vger.kernel.org, Paul Walmsley , linux-m68k@lists.linux-m68k.org, linuxppc-dev@lists.ozlabs.org, Richard Henderson , Guo Ren , linux-parisc@vger.kernel.org, Andrea Arcangeli , Helge Deller , Al Viro , Albert Ou , linux-um@lists.infradead.org, "H . Peter Anvin" , Janosch Frank , Sven Schnelle , Anton Ivanov , openrisc@lists.librecores.org, Thomas Bogendoerfer , linux-hexagon@vger.kernel.org, Andy Lutomirski , Stafford Horne , linux-csky@vger.kernel.org, Thomas Gleixner , linux-mips@vger.kernel.org, Paul Mackerras , Alexander Gordeev , Dinh Nguyen , Palmer Dabbelt , "David S . Miller" , Johannes Weiner , Hugh Dickins , Ingo Molnar , Peter Zijlstra , linux-riscv@lists.infradead.org, Max Filippov , Catalin Marinas , Geert Uytterhoeven , Johannes Berg , Chris Zankel , Michal Simek , x86@kernel.org, Yoshinori Sato , Dave Hansen , Richard Weinberger , Ingo Molnar References: <20220527193936.30678-1-peterx@redhat.com> From: Christian Borntraeger In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 17H2zOn_Mc5hu2MUIDRxY-AXp5vXE9mJ X-Proofpoint-ORIG-GUID: M8apowNso6iR-DwO9jx-r0DSHd-NwVxB X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-30_03,2022-05-27_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 adultscore=0 mlxscore=0 bulkscore=0 malwarescore=0 spamscore=0 clxscore=1011 mlxlogscore=980 lowpriorityscore=0 phishscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2205300050 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 29.05.22 um 22:33 schrieb Heiko Carstens: [...] > > Guess the patch below on top of your patch is what we want. > Just for clarification: if gmap is not NULL then the process is a kvm > process. So, depending on the workload, this optimization makes sense. > > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c > index 4608cc962ecf..e1d40ca341b7 100644 > --- a/arch/s390/mm/fault.c > +++ b/arch/s390/mm/fault.c > @@ -436,12 +436,11 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) > > /* The fault is fully completed (including releasing mmap lock) */ > if (fault & VM_FAULT_COMPLETED) { > - /* > - * Gmap will need the mmap lock again, so retake it. TODO: > - * only conditionally take the lock when CONFIG_PGSTE set. > - */ > - mmap_read_lock(mm); > - goto out_gmap; > + if (gmap) { > + mmap_read_lock(mm); > + goto out_gmap; > + } > + goto out; Yes, that makes sense. With that Acked-by: Christian Borntraeger