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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8EAA0C98304 for ; Wed, 23 Sep 2026 15:54:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 955AF6B0088; Wed, 23 Sep 2026 11:54:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 92E246B008A; Wed, 23 Sep 2026 11:54:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 844116B008C; Wed, 23 Sep 2026 11:54:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 677916B0088 for ; Wed, 23 Sep 2026 11:54:09 -0400 (EDT) Received: from smtpin18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 511C9140520 for ; Wed, 23 Sep 2026 15:54:08 +0000 (UTC) X-FDA: 85245473376.18.D5C074B Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf31.hostedemail.com (Postfix) with ESMTP id A9FD820008 for ; Wed, 23 Sep 2026 15:54:06 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=kO69tl0G; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf31.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790178846; h=from:from:sender: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:dkim-signature; bh=wAV8stNGXVD0suD8B1a8qtsl7mm0RfyqHixhi/NZx3k=; b=tXVu6pCG/ZIU4YmDY+YHMLyT9wOjBrLQhdbB0WeB66NWn1hub4kpZPDgwMyoDltFcNIsuA cuP82dX2T1kb5pFVZD8yqD8NlRUaiDGpyUFWS6dyzSPrjw0cbgnjaXUIkyWMg18qKt7qf2 cuen4/6se67Cw0IeXKqbqHCdPey4Zl4= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=kO69tl0G; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf31.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790178846; b=Wxcp2HTiCMTs5SQ8bdmRly/YOFPAGZGojB7TgTP2HKxfz9u98bKbqjBsKbed6tKbGqVctn L7cRGYaCSx14krUrHIQB1TC/zItJgpYSizkW2dafrW88GYP2joyAUflRb2qHdnrHVcZ0hf oX1b70+o22LsvIdEz52E4+zH08GyqGM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 857E960D79; Wed, 23 Sep 2026 15:54:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EF3C1F000FF; Wed, 23 Sep 2026 15:53:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790178845; bh=wAV8stNGXVD0suD8B1a8qtsl7mm0RfyqHixhi/NZx3k=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=kO69tl0GVqEJBDtzXtj722GeS02r981KicvQg4cQHtdo8zYbHSuzX4xKugLSuxZ80 hNKF+inpI1rG93f1F5QhrTtVFxLcKRCTL+snyRWCp/N/q3HEczsFeIqExmwrr7tt/Y BvYVVTOYIPgApkyrBXMn24Qh05xMwuFcGHVzqgJTNe/gle65zMUCXYN6+65S4HSHY7 tGBuhIwWJ1Pazb14YseddKo0V64lXM6Wy4pe1LmUGi7p3l+GZYljbhlHPVyxqBuygF nqC8DLo3R+mPNhwr+2JNkPsIA6gODez9Nt0VUzmMq2DMdlQhA1/ymS6rMHMT1y9mfa Lr1sgEWelyeVQ== Date: Wed, 23 Sep 2026 16:53:33 +0100 From: "Lorenzo Stoakes (ARM)" To: Suren Baghdasaryan Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Mike Rapoport , 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 , Zi Yan , 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 02/40] mm/vma: predicate setting mmap_prepare VMA fields on new vma alloc Message-ID: References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-2-4583d8a23bca@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: 3kttfq9mpk6cfoyj58s6jsp3drkrsij5 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A9FD820008 X-HE-Tag: 1790178846-975713 X-HE-Meta: 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 OqyEgYQz rnG07l7+EnuOSkNT8TH/n4m0kd/9iYExtUMkXs5WBHwL6XNS0b+E5CWP2NrF7y5fYfqQUfuK52LFOnKpzIMtLzc2q0FiDb5yDhVBNQT04Jo9bsnbj4ebDAoetjDnGOdDDszgK+rpiq2lSrdrpGfSu5eMQQ+4pxhbbHP1+6hOf+A1sAq5Mdlb2w+60/dHQx0lU7EFGK0hP9o6EgVGBFocdYh82O8B8VIxP8vwz0SGgXpokRj2beB3i54vEICdFVDi7S/Ixlv2Wsz14DbjU0q680uOsYiI0hlmJm8l9C9pW3efIY8rP58EOv39NqKqUyA78nCWjpesx9tTJXqsZXcupv/WIu2vlxXxhqpEaoZl+f+HdoCcsRliLyAOvLByudPXDpKW7eIDubED1wpMkESIOYbMWNAxXD/DQCGqRgzqXOFthjDqAB+tfTfTi4i3vRIT2vFiIrMWnJh7Q19qJz4UbPYUaxR18u4xsD3b8BFZK3HzZ6y8WPenncqEFYnC9020IVZd4ZXPFJMhvpv5Hz/jFKq8kilF0heUr30xaX0gcoEN46knkyyfKCzTzrNTrT2EleFU26GqMrIYrH/1lryqxXygtvEyAy0xdfHkuDmHsP3MR0xzEO1QyeLk2Pz54u9WVp1BhyqxtvelvwNeVuBDwPkw2TQIi4zUNLr5JKb3vFvO3AdAL9ujE4m/RVz8XwrfX73ukYXneA7hP9PRnn0TFUuSUU9aCrKWHfNEw4K3tq5bXR7bNw8OmyYE+Kiw3z4K92psbJjVZSIxk1hGqzeLcGW3kCn+qHyqCdICQG3k8DDpGdVmgvX27KcB4ExjFiTNpblI2xf60VnwbBXh9VRz4XTQOx0UyaSHIz6AQcgtCTi1HuGzrwyvkYsCgm7d3Hjt0dM89M+R9MhcpJNo32TjSFHFcjT/zYklT9PdcwURCUUyJ37VUbkjYmIi0mzvmPkjkNZV1kKy78U8T61Th7Peb3ueNIsys xt8zGdLU 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 N1tQgDFn 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 LzMJkIvw 2urVSPZopygCUCl37v8NP10s7B+EZgQJcyKnpZrQQRvre7GPMSsRbkCP96uc6VsGD0tOVovwD4Hk+TvzbY7dTRH06lxmE/VxXzgCm8w0s0vBLQ5ogQ5NokGiPYmhO35JjpeDq4a0bBsEtfI/y7fX7oM2cEFj0CbaHJqND/0AzoTPtCYY4JQVk3bAmwkf2dXXOE4hPr1Qqmau74soJbcMYwfBpvnkjWAFRht5mvY7o27SEEqoEK9tRkotbTfhq56oE7V8rLVlP+4686XCcujPDHUAQF3afO/sxe6jjkclEInSPLsmTt49E8GUuqKw2L1MIxJ7h05E/uhlHofCyrG1AYhos1Qu4BSiUueha6JI0YheK+PGfdEA8MAYyQpU7VtUl7PefUPJirGLJ8YlKwaW8/dfGMmKM5txY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 23, 2026 at 08:32:43AM -0700, Suren Baghdasaryan wrote: > On Thu, Sep 17, 2026 at 9:24 AM Lorenzo Stoakes (ARM) wrote: > > > > It only makes sense to manipulate VMA fields if we allocated a new VMA, > > rather than merged it. > > > > VMA merging does not compare vm_ops or vm_private_data, so a merged VMA > > keeps its own, which is also what the legacy f_op->mmap path does since it > > never touches an existing VMA. Previously set_vma_user_defined_fields() > > overwrote the merged VMA's fields with those set for the new mapping. In > > practice these are the same values, with rare exceptions such as shmem > > selecting vm_ops based on whether the file has been unlinked, so no > > user-visible change is expected. > > > > Make this dependency explicit, and additionally constify have_mmap_prepare > > while we're here. > > The fact that we might be overriding attributes of an existing VMA > that we merged with is technically a bug even if we never hit it, > right? If so, should we have: > > Fixes: c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback") It's not a bug, it is an in-built assumption that the state used to assess mergeability implies the same properties. And if it was, it'd need fixing a different way (check the field for instance) and would apply to the legacy mmap hook also. This change is needed for the series though. > > > > > Signed-off-by: Lorenzo Stoakes (ARM) > > Reviewed-by: Suren Baghdasaryan Thanks! > > > --- > > mm/vma.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/vma.c b/mm/vma.c > > index fa784f069da4..4b74b48c29b7 100644 > > --- a/mm/vma.c > > +++ b/mm/vma.c > > @@ -2894,7 +2894,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, > > { > > struct mm_struct *mm = current->mm; > > struct vm_area_struct *vma = NULL; > > - bool have_mmap_prepare = file && file->f_op->mmap_prepare; > > + const bool have_mmap_prepare = file && file->f_op->mmap_prepare; > > VMA_ITERATOR(vmi, mm, addr); > > const pgoff_t anon_pgoff = addr >> PAGE_SHIFT; > > MMAP_STATE(map, mm, &vmi, addr, len, pgoff, anon_pgoff, vma_flags, file); > > @@ -2937,7 +2937,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, > > allocated_new = true; > > } > > > > - if (have_mmap_prepare && !map_is_anon(&map)) > > + if (have_mmap_prepare && allocated_new && !map_is_anon(&map)) > > set_vma_user_defined_fields(vma, &map); > > > > __mmap_complete(&map, vma); > > > > -- > > 2.55.0 > > -- Cheers, Lorenzo