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 766A9C169C4 for ; Tue, 12 Feb 2019 02:57:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4BFEC2084D for ; Tue, 12 Feb 2019 02:57:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727980AbfBLC5i (ORCPT ); Mon, 11 Feb 2019 21:57:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42080 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727045AbfBLC5i (ORCPT ); Mon, 11 Feb 2019 21:57:38 -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 A310B5947A; Tue, 12 Feb 2019 02:57:37 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id C350B600C6; Tue, 12 Feb 2019 02:57:31 +0000 (UTC) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , peterx@redhat.com, Martin Cracauer , Shaohua Li , Marty McFadden , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: [PATCH v2 05/26] mm: gup: allow VM_FAULT_RETRY for multiple times Date: Tue, 12 Feb 2019 10:56:11 +0800 Message-Id: <20190212025632.28946-6-peterx@redhat.com> In-Reply-To: <20190212025632.28946-1-peterx@redhat.com> References: <20190212025632.28946-1-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 [10.5.110.39]); Tue, 12 Feb 2019 02:57:37 +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 fa75a03204c1..ba387aec0d80 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; } @@ -943,17 +946,23 @@ 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