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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, 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 AC755C10F14 for ; Tue, 16 Apr 2019 13:46:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D05F21B68 for ; Tue, 16 Apr 2019 13:46:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729490AbfDPNqw (ORCPT ); Tue, 16 Apr 2019 09:46:52 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58252 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729475AbfDPNqt (ORCPT ); Tue, 16 Apr 2019 09:46:49 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3GDkXmA178404 for ; Tue, 16 Apr 2019 09:46:48 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2rwfpusema-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 16 Apr 2019 09:46:45 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 16 Apr 2019 14:45:39 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (9.149.109.197) by e06smtp02.uk.ibm.com (192.168.101.132) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 16 Apr 2019 14:45:29 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3GDjSvi36962434 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Apr 2019 13:45:28 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5A08D4C044; Tue, 16 Apr 2019 13:45:28 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4AD3D4C058; Tue, 16 Apr 2019 13:45:26 +0000 (GMT) Received: from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.101.4.33]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 16 Apr 2019 13:45:26 +0000 (GMT) From: Laurent Dufour To: akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , aneesh.kumar@linux.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , sergey.senozhatsky.work@gmail.com, Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, Daniel Jordan , David Rientjes , Jerome Glisse , Ganesh Mahendran , Minchan Kim , Punit Agrawal , vinayak menon , Yang Shi , zhong jiang , Haiyan Song , Balbir Singh , sj38.park@gmail.com, Michel Lespinasse , Mike Rapoport Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, npiggin@gmail.com, paulmck@linux.vnet.ibm.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v12 01/31] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Date: Tue, 16 Apr 2019 15:44:52 +0200 X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190416134522.17540-1-ldufour@linux.ibm.com> References: <20190416134522.17540-1-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19041613-0008-0000-0000-000002DA6FA8 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19041613-0009-0000-0000-00002246A82F Message-Id: <20190416134522.17540-2-ldufour@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-16_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904160093 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This configuration variable will be used to build the code needed to handle speculative page fault. By default it is turned off, and activated depending on architecture support, ARCH_HAS_PTE_SPECIAL, SMP and MMU. The architecture support is needed since the speculative page fault handler is called from the architecture's page faulting code, and some code has to be added there to handle the speculative handler. The dependency on ARCH_HAS_PTE_SPECIAL is required because vm_normal_page() does processing that is not compatible with the speculative handling in the case ARCH_HAS_PTE_SPECIAL is not set. Suggested-by: Thomas Gleixner Suggested-by: David Rientjes Signed-off-by: Laurent Dufour --- mm/Kconfig | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/Kconfig b/mm/Kconfig index 0eada3f818fa..ff278ac9978a 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -761,4 +761,26 @@ config GUP_BENCHMARK config ARCH_HAS_PTE_SPECIAL bool +config ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT + def_bool n + +config SPECULATIVE_PAGE_FAULT + bool "Speculative page faults" + default y + depends on ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT + depends on ARCH_HAS_PTE_SPECIAL && MMU && SMP + help + Try to handle user space page faults without holding the mmap_sem. + + This should allow better concurrency for massively threaded processes + since the page fault handler will not wait for other thread's memory + layout change to be done, assuming that this change is done in + another part of the process's memory space. This type of page fault + is named speculative page fault. + + If the speculative page fault fails because a concurrent modification + is detected or because underlying PMD or PTE tables are not yet + allocated, the speculative page fault fails and a classic page fault + is then tried. + endmenu -- 2.21.0