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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 850E5C43441 for ; Wed, 21 Nov 2018 06:21:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56D842145D for ; Wed, 21 Nov 2018 06:21:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 56D842145D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728190AbeKUQzB (ORCPT ); Wed, 21 Nov 2018 11:55:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41006 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbeKUQzB (ORCPT ); Wed, 21 Nov 2018 11:55:01 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DA7BC89ACE; Wed, 21 Nov 2018 06:21:52 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-128.nay.redhat.com [10.66.14.128]) by smtp.corp.redhat.com (Postfix) with ESMTP id 74DD2600C3; Wed, 21 Nov 2018 06:21:44 +0000 (UTC) From: Peter Xu To: linux-kernel@vger.kernel.org Cc: Keith Busch , Jerome Glisse , peterx@redhat.com, Dan Williams , linux-mm@kvack.org, Matthew Wilcox , Al Viro , Andrea Arcangeli , Huang Ying , Mike Kravetz , Mike Rapoport , Linus Torvalds , "Michael S. Tsirkin" , "Kirill A . Shutemov" , Michal Hocko , Vlastimil Babka , Pavel Tatashin , Andrew Morton Subject: [PATCH RFC v3 4/4] mm: gup: allow VM_FAULT_RETRY for multiple times Date: Wed, 21 Nov 2018 14:21:03 +0800 Message-Id: <20181121062103.18835-5-peterx@redhat.com> In-Reply-To: <20181121062103.18835-1-peterx@redhat.com> References: <20181121062103.18835-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 21 Nov 2018 06:21:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is the gup counterpart of the change that allows the VM_FAULT_RETRY to happen for more than once. Signed-off-by: Peter Xu --- mm/gup.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index a40111c742ba..7c3b3ab6be88 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -528,7 +528,10 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma, if (*flags & FOLL_NOWAIT) fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT; if (*flags & FOLL_TRIED) { - VM_WARN_ON_ONCE(fault_flags & FAULT_FLAG_ALLOW_RETRY); + /* + * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED + * can co-exist + */ fault_flags |= FAULT_FLAG_TRIED; } @@ -944,17 +947,23 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, /* VM_FAULT_RETRY triggered, so seek to the faulting offset */ pages += ret; start += ret << PAGE_SHIFT; + lock_dropped = true; +retry: /* * Repeat on the address that fired VM_FAULT_RETRY - * without FAULT_FLAG_ALLOW_RETRY but with + * with both FAULT_FLAG_ALLOW_RETRY and * FAULT_FLAG_TRIED. */ *locked = 1; - lock_dropped = true; down_read(&mm->mmap_sem); ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED, - pages, NULL, NULL); + pages, NULL, locked); + if (!*locked) { + /* Continue to retry until we succeeded */ + BUG_ON(ret != 0); + goto retry; + } if (ret != 1) { BUG_ON(ret > 1); if (!pages_done) -- 2.17.1