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 905904D37B3; Mon, 12 Oct 2026 19:12:02 +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=1791832324; cv=none; b=SmJ4/klyXVJvnXRNACJv51OPrSHbPxyo7xhvDCPIUcO2n+CJbw/hEWpgAGm2xzkk+UtFFVcEggOh+JfjVW0kxbFFi0ANADDJi4Hvu80Wht6C6fc2wqJD8cFJr4t8pHSJn5GPxZcd0h1jopEa/h7BHOhISv0PYM+vAW34dhFkk0s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791832324; c=relaxed/simple; bh=FdkP+D43EN+xQd/ndnjr780pUFvJoTrEDYoQqVAKW9Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=l0UQiJo/+lDQDa5CJ9dKoqj/m51mCTrh3Sx6jpn1CoJKCwTk1aBgCJTTPutRND9ZIt/o43Oc4InVsPyeofAztQJZD8ih39/qeGtvXFKngLN2FM19E10q0DeZ4N/KuJegboSEoC0SZnFkvlhTGVPQ7ZqQ19zsS8yKEjO5T9yEnv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BEu0ArYB; 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="BEu0ArYB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58B361F0089B; Mon, 12 Oct 2026 19:11:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791832322; bh=t5mO4SpyqVviWjSaaEv8n4NUJ8+LaAHDu09XG7kSbFs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BEu0ArYB5XZKL/22X+idpyNhILy00Ml5Fj2jTZ7Fk/4tKlvNrtbcuHyIbatS1i6+H EgraXbynE/kQHml4oxd8zg6gA+C0hu9dN4/bgco2QE++oQB5bH8DxThhNACrQfpLo5 XjczelQ46llI8hh5qdyeZlOGyGOojXJ0MYtBFM6yqvzpX+4jdT2meUTVQWDtflbCXM 6iF5pmWBFtkh91Se1FhzLeFVS17tfaVz+ddcjoVeEnKq4qW/b4a4Az4vnWO1vg7GEy PxJnHj6TKtLcX2c2xZZNIY6SbIQi0/ch6peXKK7YGg1Kjv6Q5wlicS2sXtSXi+SohG UEkXkdb5KImtQ== Date: Mon, 12 Oct 2026 20:11:27 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (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 Subject: Re: [PATCH v5 13/38] bpf: arena: mark arena_map_mmap() mappings VM_MIXEDMAP Message-ID: 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> <4124106e-c51e-4476-bd67-63e4641bf14a@kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4124106e-c51e-4476-bd67-63e4641bf14a@kernel.org> On Mon, Oct 12, 2026 at 08:56:23PM +0200, David Hildenbrand (Arm) wrote: > 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. Well the name is confusing as a great many users never mix anything, and it's far from obvious you need to set one. Anyway, one for later. Maybe a mask like VMA_NON_MM_MANAGED_MASK or something better than that... > > > > >> 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. I think mixed map could do with a rename because it implies it _is_ mixed rather than could be. But again one for the future! > > (again, the ->fault thing returning allcoated kernel memory is nasty) Yeah added to my todo to fix that. Hateful. -- Cheers, Lorenzo