From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB1DD3B8BD4; Mon, 12 Oct 2026 18:56:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791831421; cv=none; b=puTLtYRkmmisIR4SjMQ47ZMXZdasrvqLgU77EoUn31wvQyfz5zxKaurfBmJ3gD53+gST2j9AujJxaQaQB0XBr3bE0eioYgrp9oW0tHuIQx3CGoOQbxAJPCNulNotmaPnOV7TUC/qaezONdhvAdgxl82aqj+igVRL7jBBsY5cL/M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791831421; c=relaxed/simple; bh=ik4LHcW6sEjfwQU1cHLwqQGAWffS0de5zV8j0cwRfE8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jv3hepXcGXeYNr3ZltxDpkebfJmynQEnhbdXMS5k/+6o3426zZvCM6W5OYtPiHEm5S0J87Jw0gCHVtpuZsvfP6EKkB3KRHaJaPMOZzv0EhDiVM9wwvKYFtCLxIbRnuG+SavJRgGvrfWjUgb1MHFsO37DKPKjrLP9iK1Fowo04DY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bm8mYN7N; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bm8mYN7N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31EC21F0089B; Mon, 12 Oct 2026 18:56:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791831419; bh=PTP8jRLZqHJYYCJdjNKIR4gbRyey/kI+sfcrw+3IbSA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Bm8mYN7NCuVqJWvDQ6HeMDQgHW56vGjF8/wxqiemm+bd4XmiznESMJg7H6sinCrPZ GZV7rPVLL4c96uF233hGQASQqEN2lktuU7TPySarXIcDirkjehuR9NEWkWwAEoWNkE 3RkmfTFQ3M+rQGQn1ltRovDD8fexILp4RameZqID6330p5FofggyKxZKeFhdRVSn0v Cz0eHSlFKc21spb7cHAfXKwwUgbarEpbRn2T9NuuxmjpZZNP4MxauxEdyEed/b9hrO GJqMnk1VIxCocs/eQrIixEL23q/oEUQNt41MRBaq/vsTI3LF5rjyg6hCs2s3qeSIOT uC2OpBp+V/Fbw== Message-ID: <4124106e-c51e-4476-bd67-63e4641bf14a@kernel.org> Date: Mon, 12 Oct 2026 20:56:23 +0200 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 13/38] bpf: arena: mark arena_map_mmap() mappings VM_MIXEDMAP 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" , 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, Ihor Solodrai , Bert Karwatzki , Emil Tsalapatis References: <20261009-b4-mmap-prepare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org> <20261009-b4-mmap-prepare-vma-flag-sanify-v5-13-923b70125b1e@kernel.org> <5b8ef0ce-7429-4d74-b4da-a0561c59b1e2@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/12/26 17:55, Lorenzo Stoakes (ARM) wrote: > On Mon, Oct 12, 2026 at 05:08:09PM +0200, David Hildenbrand (Arm) wrote: >> On 10/9/26 20:04, Lorenzo Stoakes (ARM) wrote: > >>> diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c >>> index 7b6847200b43..b69fe5e34339 100644 >>> --- a/kernel/bpf/arena.c >>> +++ b/kernel/bpf/arena.c >>> @@ -620,8 +620,9 @@ static int arena_map_mmap(struct bpf_map *map, struct vm_area_struct *vma) >>> * clears VM_MAYEXEC. Set VM_DONTEXPAND to avoid potential change >>> * of user_vm_start. Set VM_DONTCOPY to prevent arena VMA from >>> * being copied into the child process on fork. >>> + * This is a kernel page so set VM_MIXEDMAP. >>> */ >>> - vm_flags_set(vma, VM_DONTEXPAND | VM_DONTCOPY); >>> + vm_flags_set(vma, VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTCOPY); >>> vma->vm_ops = &arena_vm_ops; >>> return 0; >>> } >>> >> >> Historically, VM_MIXEDMAP really just means: can contain refcounted and >> non-refcounted things. Everything with a struct page is refcounted. >> >> I think we are now changing the semantics to mean "maps kernel pages". I think > > Yes. > > It was sort of implicit before given insert_page() etc. but still really meaning > that it _might_ be both. Yeah, it's in the name. Mixed: pfn and/or ordinary. > >> this is fine, but we really have to update the documentation (and possibly >> rename this thing to something more expressive?) > > Yeah I completely agree. > > I will rename it, but I think that's best for 7.5 obviously! :) Yes. VM_PFNMAP / VM_MIXEDMAP - These contain kernel-mapped data which cannot be reasonably reconstructed on page fault. the description is already pretty clear. just not that kernel-mapped pages *must* use one of these. (again, the ->fault thing returning allcoated kernel memory is nasty) -- Cheers, David