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 67DC1CA5FDD for ; Fri, 2 Oct 2026 13:12:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 376C46B0088; Fri, 2 Oct 2026 09:12:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 303E86B008A; Fri, 2 Oct 2026 09:12:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1A1CE6B008C; Fri, 2 Oct 2026 09:12:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id E592B6B0088 for ; Fri, 2 Oct 2026 09:12:03 -0400 (EDT) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7E087C0755 for ; Fri, 2 Oct 2026 13:12:03 +0000 (UTC) X-FDA: 85277724126.19.E997C27 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf06.hostedemail.com (Postfix) with ESMTP id BE44D180005 for ; Fri, 2 Oct 2026 13:12:01 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=EHWU0mbT; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790946721; 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=QbhUP9iXRT9busjJARvsVsEKsH2Ps/ZqLFS4bca4bFI=; b=tXtUenJhy6a8nVXonZ8givJ0fap+ADxBTE981nz8+OEBdlEd3zbS2tMf1n9SCqtKOhQ6P4 yn7wn1Urr3F5wIZ0LdUT0gfBpFUk53nxwBpalsWHA39/mECdAbjjAHILriuSoVN0i0jevA wZDpLYPbiu9qgYNmjqTrKG9kIpZV3xU= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=EHWU0mbT; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790946721; b=TP1M4p4ULPOw8pATvnC1TyrpEqJpma4l7rXkcc56Lf133gYpsIbhi40bB0OjM1tJShN4HI ccj15K7SX8gOByZs3w1BvCqgRZ+cDX5jtAEmG+iLePpXMQdHC6h34r5a3vhg6xhN4bUisX WdIUbKQUwZ3lCPml563umUpaBu7j+9k= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id C074C60A8D; Fri, 2 Oct 2026 13:12:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDC6B1F000FF; Fri, 2 Oct 2026 13:11:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790946720; bh=QbhUP9iXRT9busjJARvsVsEKsH2Ps/ZqLFS4bca4bFI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EHWU0mbTANCXNOi3Zz8vfaluwXiHb6NrEeQE3579lOgrAlHyG4bhLJxtrP5SUxJ53 qyuyt7WwDms+J9SU6tj1doNb8ixs5S/dfzu1LKAyzLmCA11j1Lj0zCtK60fbB19ybx 3qiK3mWy3UStlhPrmaJU1AZq+hxZAKISulldff17r1WWYubrmXtDF0LmP4+X+Wm6bd BOzsfTZ78ABQCyKcm+yss2YPRtG6Dauzuh8gKGZxzEuKnmayEwg8S4NJjxmkbEjVzs TlQyReq4OVNz5qAdPorvbksNtN11kzuoPIYJM5l9/ocKXRgGPmsMbmcutbMweewTer BEcqQ9TLZwBbw== Message-ID: <3387642b-c39f-4f19-ba0c-267bbd2fe91d@kernel.org> Date: Fri, 2 Oct 2026 15:11:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 31/40] mm/vma: introduce vma[_flags]_is_persistent() To: "Lorenzo Stoakes (ARM)" Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , 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 , 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 References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-31-4583d8a23bca@kernel.org> <9bbdf4e8-6984-4477-a183-f0b236047381@kernel.org> <3557015d-23dd-41ef-9832-78b58587f3f4@kernel.org> <81e1e5ae-0aab-4584-81e6-3fc9c2634d07@kernel.org> <2e5a4e6c-8f9c-4050-8998-454b83f4823b@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: yky391uyxj5fapuojohys68pnnx3s5nc X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: BE44D180005 X-HE-Tag: 1790946721-880851 X-HE-Meta: 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 D32WjD4D 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 4Bg9KNPH 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 F/GqT2PP 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 VAHt7d9/ Zxm6iv1i6k0JrZweW5ayFqPGFy7NxuYvshvB6M62nOfa/PP2OxbC0XBBawbb7pD0/TPajRj7R6LgEwVcl/IPNvLf0pqv2u423TyQPNzBQ2pulkbjkd6vuCro8p7qq+w4C2krbds6Jwd1BZMpEaChvmDPsrrrYt8eNrGoB+BPpMMZYZiuR1LyvJ62Hu8bufLx/O3u2M4khDiuWq2TsR9Q8UBgwuwdvkYycCiCZ7k/MhDv6LIBeX+NV1h6W2jedtbXLfMz2QwLkF9uMQqBbsP3zhrcHyx9Sl8uMCvfFUjJOv2PGfmshRae2evO8qNhh4hLHCzxmLtcAelO8WjnwJAGvhzWSMYKyNxSM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/2/26 14:48, Lorenzo Stoakes (ARM) wrote: > On Fri, Oct 02, 2026 at 02:35:06PM +0200, David Hildenbrand (Arm) wrote: >> On 10/2/26 14:08, Lorenzo Stoakes (ARM) wrote: >>> >>> No, see below. >>> >>> >>> Anything that requires stuff not to be dropped behind the user's back, which is >>> at least 4 cases! >>> >>> That being open-coded all over the place is a problem I think, and I think stuff >>> like the PMD device private are a reminder that open-coding all over can cause >>> problems. >>> >>> >>> There are 4 open-coded checks that test four ad-hoc flag combinations checking >>> for the same thing - 'can the kernel or a driver change things or discard stuff >>> behind my back?' >>> >>> So abstracting that to a helper, alongside the other 'let's ask based on >>> semantics' helpers, seems sensible. >>> >>> Maybe invert the meaning to make it clearer? >>> >>> vma_kernel_may_change_contents()? >>> >> >> This is all super confusing and I don't think we should try to describe the >> semantics that way. >> >> Just imagine having udmabuf use a PFNMAP of folios obtained from shmem. For sure >> the kernel could now change the shmem pages that are mapped in some ordinary VMA. > > There's always edge cases like this. > > In each of these conditionals that this helper replaces, that's exactly what's > being checked for. > > A driver could GUP anything and access the page raw and do things like that > too... > > Without this we lose all that and are back to arbitrary flag checks again. It > seems unwise. > >> >> >> Likely we don't have to squeeze everything into a single helper that is hard to >> describe. > > I'm not trying to do that :) > > There are plenty of edge cases I left alone. > > This one explicitly is one that can end up very easily broken in the future. > > Already there's been issues as I recall with people forgetting about droppable. > >> >> Maybe we can pull parts of it into a separate helper with semantics that are >> easier to describe? > > But then you lose the whole purpose of this, which is to not miss things. I think it's perfectly fine to instead have helper like vma_is_dumpable() that maybe have a single purpose but are centralized and well documented. If we can construct them out of other helpers, great. > >> >> >> vma_is_user_memory() && !vma_is_droppable_memory() > > I find vma_is_user_memory() _very_ confusing :) I have no idea what that means. If we can find some way to describe "anon+pagecache" ... maybe something around folios (future oriented). > > And vma_is_droppable_memory() is a semi-pointless wrapper for checking the > droppable flag no? Sure, no strong opinion on that. It's a bit easier on the eye than bit checks. (and can have a nicer description maybe). > >> >> Although I am not sure user_memory is exactly precise (pagecache+anon) and what >> we want? It's all super confusing (thanks for deciphering it). > > That name isn't great, as userland memory is defined as that which can be mapped > in the userland portion of the virtual memory address map, and all VMAs describe > that :) > > And then you can go on from there as to pedantic issues, the very same shmem > stuff you mention above can be put forward as an argument, etc. etc. >> >> >>> vma_contents_may_change() is shorter but easily confused with something being >>> writable by userland etc. >>> >>> Or maybe: >>> >>> vma_is_volatile() >>> >>> ? >>> >>> Which is analogous to the meaning of the volatile keyword. >> This is all confusing because persistent and volatile are established concept >> when talking about memory. And see my example above, it's not even clear what it >> means that "the kernel can modify something". > > Yep I guess volatile vs. non-volatile. > > But a VMA describes a mapping not backing and 'volatile' in C is pretty clear - > something can be touched by something else so don't make assumptions. > > I mean if people are confused they can look at the comment. We argue about > details meanwhile the code is full of terrible naming that's duplicated 100 > times :) > > And you can come up with edge cases to a lot of things. That doesn't invalidate > the intent. > > Right now the code is duplicative and I found multiple instances of e.g. drivers > doing completely the wrong thing. > > In any case, you seem to feel very strongly about this - so maybe best I drop > this patch from the series to be revisited later? I'd be very happy if we could find a clear way to describe "this is what we call user memory: anon+pagecache", if that could come handy in such a context. In the end, it's mostly all about: this is nothing special (lol), it's just ordinary user memory (anon+pagecache), and in some cases we want to also ignore weird droppable mappings, because why e.g., dump them if the context is just irrelevant. -- Cheers, David