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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 BD56EC433E1 for ; Fri, 24 Jul 2020 23:38:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94DB42070B for ; Fri, 24 Jul 2020 23:38:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595633895; bh=MfqXerlTWmruPnCjXD44JMzM+C6e1M6Dp6HE1y9ZH/c=; h=Date:From:To:Subject:Reply-To:List-ID:From; b=LVy+0UMG5vfawZMACc8jwxM9I+ucJeuAnyer19oYCk1lZ5euu2biqv3Xff/Aj9f4T US0yXVcfLyqXxjGQEoO4lLYaVSHZ6qzE6lovEq8gCsZAEZExqJznGfvc7HX2PbwR7V 6+Hi4V8o4oTPdwcdHxTs0oUdZfVCL7hkTRp1O2M8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726666AbgGXXiP (ORCPT ); Fri, 24 Jul 2020 19:38:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:43998 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726552AbgGXXiO (ORCPT ); Fri, 24 Jul 2020 19:38:14 -0400 Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A79A4206E3; Fri, 24 Jul 2020 23:38:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595633893; bh=MfqXerlTWmruPnCjXD44JMzM+C6e1M6Dp6HE1y9ZH/c=; h=Date:From:To:Subject:From; b=cMQcevUePRWtujJqVE3aQaeQM3JejDUOgOY/urhMMuUht6uvn94Lm95h0QJfihz1X MRVRGSrDzPDSYcVPCg1WlY/7tJyRFixF40tny9JO2H9IoHZxSRwQToSOf5h6K3/cLH NLtbkcJ61CfTymPebv/n7TjXytn1QKqQL9O//Tdg= Date: Fri, 24 Jul 2020 16:38:13 -0700 From: akpm@linux-foundation.org To: jannh@google.com, kirill.shutemov@linux.intel.com, mm-commits@vger.kernel.org, oleg@redhat.com, stable@vger.kernel.org, vbabka@suse.cz, willy@infradead.org, yang.shi@linux.alibaba.com Subject: [merged] mm-close-race-between-munmap-and-expand_upwards-downwards.patch removed from -mm tree Message-ID: <20200724233813.pdqrWibid%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/mmap.c: close race between munmap() and expand_upwards()/downwards() has been removed from the -mm tree. Its filename was mm-close-race-between-munmap-and-expand_upwards-downwards.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: "Kirill A. Shutemov" Subject: mm/mmap.c: close race between munmap() and expand_upwards()/downwards() VMA with VM_GROWSDOWN or VM_GROWSUP flag set can change their size under mmap_read_lock(). It can lead to race with __do_munmap(): Thread A Thread B __do_munmap() detach_vmas_to_be_unmapped() mmap_write_downgrade() expand_downwards() vma->vm_start = address; // The VMA now overlaps with // VMAs detached by the Thread A // page fault populates expanded part // of the VMA unmap_region() // Zaps pagetables partly // populated by Thread B Similar race exists for expand_upwards(). The fix is to avoid downgrading mmap_lock in __do_munmap() if detached VMAs are next to VM_GROWSDOWN or VM_GROWSUP VMA. [akpm@linux-foundation.org: s/mmap_sem/mmap_lock/ in comment] Link: http://lkml.kernel.org/r/20200709105309.42495-1-kirill.shutemov@linux.intel.com Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") Signed-off-by: Kirill A. Shutemov Reported-by: Jann Horn Acked-by: Vlastimil Babka Reviewed-by: Yang Shi Cc: Oleg Nesterov Cc: Matthew Wilcox Cc: [4.20+] Signed-off-by: Andrew Morton --- mm/mmap.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/mm/mmap.c~mm-close-race-between-munmap-and-expand_upwards-downwards +++ a/mm/mmap.c @@ -2620,7 +2620,7 @@ static void unmap_region(struct mm_struc * Create a list of vma's touched by the unmap, removing them from the mm's * vma list as we go.. */ -static void +static bool detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, unsigned long end) { @@ -2645,6 +2645,17 @@ detach_vmas_to_be_unmapped(struct mm_str /* Kill the cache */ vmacache_invalidate(mm); + + /* + * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or + * VM_GROWSUP VMA. Such VMAs can change their size under + * down_read(mmap_lock) and collide with the VMA we are about to unmap. + */ + if (vma && (vma->vm_flags & VM_GROWSDOWN)) + return false; + if (prev && (prev->vm_flags & VM_GROWSUP)) + return false; + return true; } /* @@ -2825,7 +2836,8 @@ int __do_munmap(struct mm_struct *mm, un } /* Detach vmas from rbtree */ - detach_vmas_to_be_unmapped(mm, vma, prev, end); + if (!detach_vmas_to_be_unmapped(mm, vma, prev, end)) + downgrade = false; if (downgrade) mmap_write_downgrade(mm); _ Patches currently in -mm which might be from kirill.shutemov@linux.intel.com are