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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75F61C432C0 for ; Mon, 18 Nov 2019 13:50:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EA3E20748 for ; Mon, 18 Nov 2019 13:50:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726909AbfKRNup (ORCPT ); Mon, 18 Nov 2019 08:50:45 -0500 Received: from www62.your-server.de ([213.133.104.62]:35012 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726596AbfKRNup (ORCPT ); Mon, 18 Nov 2019 08:50:45 -0500 Received: from sslproxy05.your-server.de ([78.46.172.2]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1iWhQR-00022r-8J; Mon, 18 Nov 2019 14:50:43 +0100 Received: from [2a02:1205:507e:bf80:bef8:7f66:49c8:72e5] (helo=pc-11.home) by sslproxy05.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1iWhQQ-000Udz-VQ; Mon, 18 Nov 2019 14:50:42 +0100 Subject: Re: [PATCH v6 bpf-next 0/5] Add support for memory-mapping BPF array maps To: Andrii Nakryiko , bpf@vger.kernel.org, netdev@vger.kernel.org, ast@fb.com Cc: andrii.nakryiko@gmail.com, kernel-team@fb.com References: <20191117172806.2195367-1-andriin@fb.com> From: Daniel Borkmann Message-ID: <04403b43-3a08-e63e-729e-5f9e66ca0dc2@iogearbox.net> Date: Mon, 18 Nov 2019 14:50:42 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20191117172806.2195367-1-andriin@fb.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25637/Mon Nov 18 10:53:23 2019) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 11/17/19 6:28 PM, Andrii Nakryiko wrote: > This patch set adds ability to memory-map BPF array maps (single- and > multi-element). The primary use case is memory-mapping BPF array maps, created > to back global data variables, created by libbpf implicitly. This allows for > much better usability, along with avoiding syscalls to read or update data > completely. > > Due to memory-mapping requirements, BPF array map that is supposed to be > memory-mapped, has to be created with special BPF_F_MMAPABLE attribute, which > triggers slightly different memory allocation strategy internally. See > patch 1 for details. > > Libbpf is extended to detect kernel support for this flag, and if supported, > will specify it for all global data maps automatically. > > Patch #1 refactors bpf_map_inc() and converts bpf_map's refcnt to atomic64_t > to make refcounting never fail. Patch #2 does similar refactoring for > bpf_prog_add()/bpf_prog_inc(). > > v5->v6: > - add back uref counting (Daniel); > > v4->v5: > - change bpf_prog's refcnt to atomic64_t (Daniel); > > v3->v4: > - add mmap's open() callback to fix refcounting (Johannes); > - switch to remap_vmalloc_pages() instead of custom fault handler (Johannes); > - converted bpf_map's refcnt/usercnt into atomic64_t; > - provide default bpf_map_default_vmops handling open/close properly; > > v2->v3: > - change allocation strategy to avoid extra pointer dereference (Jakub); > > v1->v2: > - fix map lookup code generation for BPF_F_MMAPABLE case; > - prevent BPF_F_MMAPABLE flag for all but plain array map type; > - centralize ref-counting in generic bpf_map_mmap(); > - don't use uref counting (Alexei); > - use vfree() directly; > - print flags with %x (Song); > - extend tests to verify bpf_map_{lookup,update}_elem() logic as well. > > Andrii Nakryiko (5): > bpf: switch bpf_map ref counter to atomic64_t so bpf_map_inc() never > fails > bpf: convert bpf_prog refcnt to atomic64_t > bpf: add mmap() support for BPF_MAP_TYPE_ARRAY > libbpf: make global data internal arrays mmap()-able, if possible > selftests/bpf: add BPF_TYPE_MAP_ARRAY mmap() tests > Applied, thanks!