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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4E36C77B7E for ; Tue, 2 May 2023 11:31:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234041AbjEBLbB (ORCPT ); Tue, 2 May 2023 07:31:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233854AbjEBLay (ORCPT ); Tue, 2 May 2023 07:30:54 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1469761BF for ; Tue, 2 May 2023 04:29:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1683026959; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=d6aVfBAvC6NPqJutohdZRgZHqJFIUz73CuJW91t7YXY=; b=aIFck+VJjz3PX2aZZvkJ907Ee+NAQ9QOQ+UPuX+2LyngSz4uXZhoN2bk0G4ncCwYZT7GrO EAp3fY2JqUNnlvpLAEfDgBKPnFubMcozyjzZw03TxEWAQcMD/IkCu3vGRnAJNczQDVTg1C ziZHnCEVj80grd/Mv0phZ429fnw90gg= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-122-kQvKpZMqMFixecXc4IKvWw-1; Tue, 02 May 2023 07:29:18 -0400 X-MC-Unique: kQvKpZMqMFixecXc4IKvWw-1 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-3063287f1c9so472777f8f.2 for ; Tue, 02 May 2023 04:29:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683026957; x=1685618957; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=d6aVfBAvC6NPqJutohdZRgZHqJFIUz73CuJW91t7YXY=; b=i1PLTP9HpPfNbPwvjDIPEVFr+WPN2UM5MrNlhGNT30/hoah9QGKxBPAhMWIKJJpG67 iBv0vJBWrfz9+ec8kgCcCPQiz4TlntTBWCIOxdWmbZzWdDx5b8+nAtbMC2Jv6rDeGCjK 9OebbT2vW2WWrCcXGF6mySkhOeBstTHQFoEDiifF4390q/3+4SJfHGtF5GVH53Gc4nE5 WgvRuIfTvGqFQdzJ+fkNKaBE6a2NTILZxjQoSE3XPW1td9hnd/hbBOlQEfh3JOEWjGkM uCwFi/q9y9TRvRHFSOVoC5zcN87DWg/mikpk6kb/YzodXySI9+mbJAZRpKhpXti89FAr A6bg== X-Gm-Message-State: AC+VfDxHPwO0UEQlqJ9Hkb5g/VE4UVyXP+geVf+A5xGj7JceiY2OE5I6 95RzukJBz3bydCOPRdQkdAGm5OXlH9/R2xDFn0DfDJr3BUuf2VY2hVW1HYbcLy+My+l9jfQ++Gq P4TcxIxyKwkRlQLlM5qdIzMuZ X-Received: by 2002:adf:fc06:0:b0:2f6:c5bd:ba13 with SMTP id i6-20020adffc06000000b002f6c5bdba13mr11674101wrr.42.1683026956946; Tue, 02 May 2023 04:29:16 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6bEO/bFsCBL4jjeOERe16Ibe/XR3jODjkuD+y3N9E8JZP4WIpgsT8/4D+NHBTnn88co0L8Bg== X-Received: by 2002:adf:fc06:0:b0:2f6:c5bd:ba13 with SMTP id i6-20020adffc06000000b002f6c5bdba13mr11674084wrr.42.1683026956636; Tue, 02 May 2023 04:29:16 -0700 (PDT) Received: from ?IPV6:2003:cb:c700:2400:6b79:2aa:9602:7016? (p200300cbc70024006b7902aa96027016.dip0.t-ipconnect.de. [2003:cb:c700:2400:6b79:2aa:9602:7016]) by smtp.gmail.com with ESMTPSA id c10-20020adffb0a000000b00306344eaebfsm2359522wrr.28.2023.05.02.04.29.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 May 2023 04:29:16 -0700 (PDT) Message-ID: <06301913-9289-6654-5851-16cf8066c6b4@redhat.com> Date: Tue, 2 May 2023 13:29:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH] mm/mmap/vma_merge: always check invariants Content-Language: en-US To: Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: "Liam R . Howlett" , Vlastimil Babka References: From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30.04.23 22:19, Lorenzo Stoakes wrote: > We may still have inconsistent input parameters even if we choose not to > merge and the vma_merge() invariant checks are useful for checking this > with no production runtime cost (these are only relevant when > CONFIG_DEBUG_VM is specified). > > Therefore, perform these checks regardless of whether we merge. > > This is relevant, as a recent issue (addressed in commit "mm/mempolicy: > Correctly update prev when policy is equal on mbind") in the mbind logic > was only picked up in the 6.2.y stable branch where these assertions are > performed prior to determining mergeability. > > Had this remained the same in mainline this issue may have been picked up > faster, so moving forward let's always check them. > > Signed-off-by: Lorenzo Stoakes > --- > mm/mmap.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 5522130ae606..13678edaa22c 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -960,17 +960,17 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > merge_next = true; > } > > + /* Verify some invariant that must be enforced by the caller. */ > + VM_WARN_ON(prev && addr <= prev->vm_start); > + VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); > + VM_WARN_ON(addr >= end); > + > if (!merge_prev && !merge_next) > return NULL; /* Not mergeable. */ > > res = vma = prev; > remove = remove2 = adjust = NULL; > > - /* Verify some invariant that must be enforced by the caller. */ > - VM_WARN_ON(prev && addr <= prev->vm_start); > - VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end)); > - VM_WARN_ON(addr >= end); > - > /* Can we merge both the predecessor and the successor? */ > if (merge_prev && merge_next && > is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb