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=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 0553DC433E6 for ; Tue, 14 Jul 2020 07:33:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D95FA20849 for ; Tue, 14 Jul 2020 07:33:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="Z/wYVQyt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726546AbgGNHdF (ORCPT ); Tue, 14 Jul 2020 03:33:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726472AbgGNHdE (ORCPT ); Tue, 14 Jul 2020 03:33:04 -0400 Received: from mail-lj1-x244.google.com (mail-lj1-x244.google.com [IPv6:2a00:1450:4864:20::244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C213C061794 for ; Tue, 14 Jul 2020 00:33:04 -0700 (PDT) Received: by mail-lj1-x244.google.com with SMTP id q7so21315827ljm.1 for ; Tue, 14 Jul 2020 00:33:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=R8orn93ADt/4gOBW8WREoRLbcPdxazQvh/HwHNIuhAY=; b=Z/wYVQytSqKk3IH73/ux75nV4a9eng7MqAusYNZKDbWAhyRl1DiFjkwYNX42KabOKB j3LZ4sjY4SUzGCaSEKgB9NdJezNz+UehQo+59s/d9nVbH69yfKSQMYKMxi0afnuMg3Vt +jfoqZNsgQaj41KfbjsIM5sF4xL4ubkEvxVTjZGSYtl7M+lcUpBp6Y1ct+JOgW5Ka86O qZqqQD4TEVIWLz+mf6tYW3p/YYliDIrc3FBTgWd4soRSc3/7NRpUNqfaItmM6k8k5quc YETGoX9lodspJ+HWv7iDPcBoK/47UNGi1TP0GGW0VKMxku7BiRKhOsim8gkYmquvtTFS NIlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=R8orn93ADt/4gOBW8WREoRLbcPdxazQvh/HwHNIuhAY=; b=IXH3KE8YfSXjGXxxHkkQjG9L4EI2t2+PsMwEiImHJCgsTekqejeBKW+/rqDSzCuqPW t3sXF6r0dWL0l6lbHNfrFSUHzOU2ZBum3iANHGooRdVYjxLhre3ds2N1hNY1R6deiWzL HRIotRl1GN3aG6BzQlFrTYORK9+UX6rw9AFZlhn1Fz+YWYEa6oRQA5nJWYW75s9eiRv/ BOrPpSG2OYqDOvgb6Y2sHPjbmLHRzMOd93aY6fqPowdTbaBrhae8sYuxc9d+TBRsZuFk Ms6Q6Ehi32YTUFy/5ecwikTlljmmVS2hN/HbEW69JDfMWW4wxKIAdVSFq3sDJEEqE3z7 P6uQ== X-Gm-Message-State: AOAM530YnujjOYyr7KaOEVFJxpuf/8x2OxiePC0VNq8YfR7CHH1iiDcq Lx0iiQDkkNb5G+aFuZgDppUmkA== X-Google-Smtp-Source: ABdhPJx7Tu4+/eXTMAvrPy+NFt0qJma4hLbxqpf8m1or7AVtlxWHP6cAteAQCMqlnwkRL1E8WUItLw== X-Received: by 2002:a05:651c:3c2:: with SMTP id f2mr1714736ljp.37.1594711982733; Tue, 14 Jul 2020 00:33:02 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id i15sm5093781lfl.57.2020.07.14.00.33.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jul 2020 00:33:02 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 0F10E101459; Tue, 14 Jul 2020 10:33:06 +0300 (+03) Date: Tue, 14 Jul 2020 10:33:06 +0300 From: "Kirill A. Shutemov" To: Linus Torvalds Cc: Joel Fernandes , Naresh Kamboju , linux- stable , open list , linux-mm , Arnd Bergmann , Andrew Morton , Roman Gushchin , Michal Hocko , lkft-triage@lists.linaro.org, Chris Down , Michel Lespinasse , Fan Yang , Brian Geffon , Anshuman Khandual , Will Deacon , Catalin Marinas , pugaowei@gmail.com, Jerome Glisse , Greg Kroah-Hartman , Mel Gorman , Hugh Dickins , Al Viro , Tejun Heo , Sasha Levin Subject: Re: WARNING: at mm/mremap.c:211 move_page_tables in i386 Message-ID: <20200714073306.kq4zikkphqje2yzb@box> References: <20200712215041.GA3644504@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 12, 2020 at 03:58:06PM -0700, Linus Torvalds wrote: > Anybody else have any opinions? Maybe we just shouldn't allow move_normal_pmd() if ranges overlap? Other option: pass 'overlaps' down to move_normal_pmd() and only WARN() if see establised PMD without overlaps being true. Untested patch: diff --git a/mm/mremap.c b/mm/mremap.c index 5dd572d57ca9..e33fcee541fe 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -245,6 +245,18 @@ unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long extent, next, old_end; struct mmu_notifier_range range; pmd_t *old_pmd, *new_pmd; + bool overlaps; + + /* + * shift_arg_pages() can call move_page_tables() on overlapping ranges. + * In this case we cannot use move_normal_pmd() because destination pmd + * might be established page table: move_ptes() doesn't free page + * table. + */ + if (old_addr > new_addr) + overlaps = old_addr - new_addr < len; + else + overlaps = new_addr - old_addr < len; old_end = old_addr + len; flush_cache_range(vma, old_addr, old_end); @@ -282,7 +294,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, split_huge_pmd(vma, old_pmd, old_addr); if (pmd_trans_unstable(old_pmd)) continue; - } else if (extent == PMD_SIZE) { + } else if (!overlaps && extent == PMD_SIZE) { #ifdef CONFIG_HAVE_MOVE_PMD /* * If the extent is PMD-sized, try to speed the move by -- Kirill A. Shutemov