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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4016CC98324 for ; Fri, 25 Sep 2026 09:55:37 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4hrmKg4vY5z3017; Fri, 25 Sep 2026 19:55:35 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=172.234.252.31 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1790330135; cv=none; b=S8gsTmclcwjBB2fvo62jholPG9wap/21R138DFe+M0Z3llCZSUcSy9fot1xcBHICDZNvDOIJd+nEoyYI3TKNIjlBnz4Otfk4COdxuwv/dwuArG36xrciQR/3jQ4EzDSm5xnY10mtrJxbXv+qPesoI68WuHUiBXl7Q0l15s0veuA57oAGemNet37skH1QT6rrTFjDlcbbB+4kyGMjqOKXfZNlyM5VSnRXOeay2T2xA6suping3Q4UOwp9xM/2bYlz+OHmivMIp5mgGBn0r/NqXv0rf+v9H9eiThF3ek1EX1pWwBUh6qPj5RG/zlQXOEcY1vdrBaTn+LTrFyu5lemruw== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1790330135; c=relaxed/relaxed; bh=wHcL5jPNS47s6Ul8XnEo1uFsA8Y0TKv8vyd/Iuc4jW8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RVDoGOQzq2b4YJSyYJQWrdl/cEqRhn4hNe0G6fDzuobgnEYeTzXETWTAlvvIpuGgDKE9khk7wsFz06w2rQv5MeTcIK5GwUKUFM0HIuekO/OvXHOlQzLRLv1VaaU+c3rmvnewAx5KCGuJUM0E/oLLXcSqKtW9EoUPyHHVo8Pf+FuIXpSIiuhWPCruREw/mpaYA8AySfokLkZJbPRr/32PprxnZV1itPLiV7K9lg95iAHuAw999YAPQpfuXPJp5iuE6VcR3w2lWzCnvdJRwz7mPsbR5IUS1XqnYSmfPDR4pCayi54y1h1Z3L6EXyUEeTULOP9VLsoKNL4zNiU0W9P6Kg== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HxJQcEvn; dkim-atps=neutral; spf=pass (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=ljs@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HxJQcEvn; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=ljs@kernel.org; receiver=lists.ozlabs.org) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4hrmKf6LpLz2ygX for ; Fri, 25 Sep 2026 19:55:34 +1000 (AEST) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id AE0F340AC5; Fri, 25 Sep 2026 09:55:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C76A1F000FF; Fri, 25 Sep 2026 09:55:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790330132; bh=wHcL5jPNS47s6Ul8XnEo1uFsA8Y0TKv8vyd/Iuc4jW8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=HxJQcEvnuhUOHH3Z6mzmWye1CE1PjDtpVrPBVFbcNDGyG6yBkjOShg1wXTRxmQKyc TCJMHEkTxA8Sxw4HyLR7LdXQhRJb+9udY3QgV8ET7cug6AZBPLxgIFx/TdmYGQ8bVU ptEgwP56FVQ2pJrDbYSWaP8xyRORQKPPWrshPWAAjxwWnAwT2YIoJgfyo9wv4EO7c3 7ozDd+omlnSWJmwSq3s1563JOKXMeNxa13jAxu5Ee20miDdmPGzcEIeZWGgnBBy5y6 eWzAFHQy56s+qgvvgTG8xUGQUmf5tQzyaZcP9CgdenUpWl9R2UycwCgDON1sf75KvU KkanjhxFaUGcw== Date: Fri, 25 Sep 2026 10:55:01 +0100 From: "Lorenzo Stoakes (ARM)" To: Zi Yan Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Greg Kroah-Hartman , Dennis Dalessandro , Jason Gunthorpe , Leon Romanovsky , Paul Moore , Stephen Smalley , Jaroslav Kysela , Takashi Iwai , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Doug Gilbert , "James E.J. Bottomley" , "Martin K. Petersen" , Jaya Kumar , Simona Vetter , Helge Deller , Sebastian Reichel , John Hubbard , Peter Xu , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Rik van Riel , Harry Yoo , Juri Lelli , Vincent Guittot , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Arnd Bergmann , Muchun Song , Oscar Salvador , "Matthew Wilcox (Oracle)" , Jan Kara , Marc Zyngier , Oliver Upton , Catalin Marinas , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , "David S. Miller" , Andreas Larsson , Alexander Viro , Christian Brauner , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park , Johannes Weiner , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chengming Zhou , Michal Hocko , Miklos Szeredi , Xu Xin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-usb@vger.kernel.org, linux-rdma@vger.kernel.org, selinux@vger.kernel.org, linux-sound@vger.kernel.org, bpf@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, fuse-devel@lists.linux.dev Subject: Re: [PATCH v3 05/40] mm/vma: ensure mmap_prepare doesn't set actions on a mergeable vma Message-ID: References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-5-4583d8a23bca@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Sep 24, 2026 at 03:28:10PM -0400, Zi Yan wrote: > On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote: > > When a user requests an mmap_action be performed in mmap_prepare, this > > involves populating the VMA range with data. > > > > However, if the VMA is mergeable, it might then mistakenly be merged with > > another VMA without having populated the range. > > > > Every mmap action currently available sets VMA flags such that the VMA > > cannot be merged. > > > > However, to ensure that no future mmap action falls foul of this, assert > > that this is the case upon mmap_prepare validation. > > > > Signed-off-by: Lorenzo Stoakes (ARM) > > --- > > mm/vma.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/mm/vma.c b/mm/vma.c > > index d6ed10cefc8f..62f2ce1ad5a1 100644 > > --- a/mm/vma.c > > +++ b/mm/vma.c > > @@ -2809,6 +2809,15 @@ static int mmap_validate(unsigned long prev_start, unsigned long prev_end, > > int mmap_prepare_validate(const struct vm_area_desc *prev_desc, > > const struct vm_area_desc *desc) > > { > > + /* > > + * It is not valid to execute mmap actions for VMAs which can be merged, > > Is it better to say "for VMAs ... after mmap_action_prepare()"? When I > first read this, I wonder why the check is done after > mmap_action_prepare(), which does some work based on action.type. Then, > I realize mmap_action_prepare() changes desc->vma_flags and affect its > mergeablitiy. Ack, good point will update! > > > + * as any such merge would leave portions of the mapping incorrectly > > + * unmapped. > > + */ > > + if (vma_flags_can_merge(&desc->vma_flags) && > > + WARN_ON_ONCE(desc->action.type != MMAP_NOTHING)) > > + return -EINVAL; > > + > > return mmap_validate(prev_desc->start, prev_desc->end, > > desc->start, desc->end, > > &prev_desc->vma_flags, &desc->vma_flags); > > > Otherwise, LGTM. > > Reviewed-by: Zi Yan Thanks! > > > -- > Best Regards, > Yan, Zi > -- Cheers, Lorenzo