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 CABAA51B196; Thu, 17 Sep 2026 16:30:08 +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=1789662610; cv=none; b=pCf+QHZHG/ruLU0sRnQo2qG6BjSUS+O6P8WJOXF/rJgXfP2KgwGOafBODZvqIH4leOg/cmUy9p1QJdmxYFyBVzI3FXe/aWbbYi7rh9Q3SjOlHAp1i61yO4YDb5mgFTFNwxNMZQ5tkebtto0GNdc/HmSUw6RRvccOk+visF/KK6w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662610; c=relaxed/simple; bh=R3tb6SjOVu7d1sP7Jc7DgfQesg/5MmuNI7Jhk6g3s7I=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=PpeN4xkSy8avY2MjLigT3wAv7/XlMKLzlRiFdATAr7qE/R9EyOLQQuGzPgAssl+715PvIrNbACP5kgI5PoxU9DFjxkGF43sR+fFAPWQ7SyDtDmyW0iEo3xkNj2s3QbTyvlnpKm8aFzm+dR3NtbBQ5Y9JU7uwifbL7K+Xpuso+hk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HFj1ZcuE; 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="HFj1ZcuE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CB891F000FF; Thu, 17 Sep 2026 16:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789662608; bh=qgN2FFKKPpmp05DaHJUklpQtNOudy/Yy1fqR/MizKYA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=HFj1ZcuEDNTMnh2Nqg6+fJfV02zj4ziSKQ6RRu3yQsj5p9v46CsiyUooZCzc+YKP8 34+cHO9Ai3c1E0itgx/XfzOSuRfYmy8HAt254s7g3BLKzyjpUAnQOVrO0QhDVNgiq3 flPs+hy1XGA0Y7fr1T5cxhyfnmG67B5FQqIFoWXsIONz3QdBqErmu8iV1XFY4RLphO IFPC2LNRFjPKPOaYpFPD72y8tC/6OnYCr6cG2Sad5uOHcVDlZ4CJ7psZsf+Fnn5m50 NrSpWB5QWg5LSJldkts2rYONeMhUptkU9gWhvtFpmXXEctHjrUlI2vfeMdLEBsJtm/ Oqt+2k9sPTlrw== From: "Lorenzo Stoakes (ARM)" Date: Thu, 17 Sep 2026 17:22:23 +0100 Subject: [PATCH v3 14/40] bpf: arena: mark arena_map_mmap() mappings VM_MIXEDMAP Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-14-4583d8a23bca@kernel.org> References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> In-Reply-To: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> To: 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 , 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 Cc: 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, "Lorenzo Stoakes (ARM)" , Emil Tsalapatis X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2130; i=ljs@kernel.org; h=from:subject:message-id; bh=R3tb6SjOVu7d1sP7Jc7DgfQesg/5MmuNI7Jhk6g3s7I=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLLWCB9I54nnNvtaIzQtQLirIc/9iwfHss/3oxY92Nyjp NYufetcRykLgxgXg6yYIsvzL+L7g0TC5nVe8HeDmcPKBDKEgYtTACby8iIjw4Z/yqcuR2/Xfn+H S/lV3fFHj2t+hpZ0/BU4/O3EpbNTVAwZGa7W9Yjb2IRpLFvWrbWlSPbedPOzxjoW/zcszF4buGz NIRYA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 The bpf_map->ops->map_mmap callback invoked by bpf_map_mmap() can be set to one of ringbuf_map_mmap_kern(), ringbuf_map_mmap_user(), array_map_mmap() or arena_map_mmap(). It is convention in mm to mark mappings whose pages the kernel manages itself with VM_MIXEDMAP, so the core mm knows not to treat them as ordinary page cache or anonymous memory. The map_mmap callbacks ringbuf_map_mmap_kern() and ringbuf_map_mmap_user() use remap_vmalloc_range(), which ultimately invokes vm_insert_page() and so marks the ranges VM_MIXEDMAP, and array_map_mmap() sets VM_MIXEDMAP explicitly. However, the exception to this is arena_map_mmap(), which doesn't set the flag. This patch corrects this and updates the comment to reflect it. The pages are refcounted and vm_normal_page() finds them regardless of the flag, and VM_DONTEXPAND remains set (marking the memory as VM_SPECIAL and thus unmergeable). The one effect is that NUMA balancing now skips these VMAs, as it already does for the other bpf map mappings, which is the reason array_map_mmap() gives for setting the flag. The intent of this patch is to be able to establish the invariant that only PFN-mapped or mixed map ranges may clear the VM_MAYWRITE flag, as is done in bpf_map_mmap(). Reviewed-by: Emil Tsalapatis Signed-off-by: Lorenzo Stoakes (ARM) --- kernel/bpf/arena.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) 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; } -- 2.55.0