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 02846D2D8DA for ; Tue, 27 Jan 2026 09:48:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 694256B00A1; Tue, 27 Jan 2026 04:48:14 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 654F26B00A2; Tue, 27 Jan 2026 04:48:14 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 56E786B00A3; Tue, 27 Jan 2026 04:48:14 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 4959F6B00A1 for ; Tue, 27 Jan 2026 04:48:14 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id F344FBD30E for ; Tue, 27 Jan 2026 09:48:13 +0000 (UTC) X-FDA: 84377268066.14.F195CA7 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) by imf13.hostedemail.com (Postfix) with ESMTP id 6CCCE20003 for ; Tue, 27 Jan 2026 09:48:12 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=KimfuEVO; spf=pass (imf13.hostedemail.com: domain of hui.zhu@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=hui.zhu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769507292; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ZDAnxBm956aOF5ZEWN5PM3SfgIASeIOgGwSIT/GymGw=; b=3EdfCh/uANao+MX/JxQGZ2L5/JIqPk7aZBi+GRzZECB8jYCDQ1oxKCONz8rxIbjF2CJ0Q6 JPPEJ82Ic7SkvDVsCni+sflRnW0uwNXYLhvO1y7kZgFroB7T1pdNkNL9sG8wDXspIOUhEa NIJA4AxMZjYc0Q/YXP9tGqTw5ugw3Uc= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=KimfuEVO; spf=pass (imf13.hostedemail.com: domain of hui.zhu@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=hui.zhu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769507292; a=rsa-sha256; cv=none; b=jm0L3Hfe7UO5x5FX5IHtTYSQInREeWKnYTK+sxb3OmQ9XTYMm1qUtZ+aqPmrcDU4bg8KR0 XKJim+Vxh0w6lN8VsV79+cAcl4QbQ7xYZNm6O6+NgVgg6gjmMfzIXC2w0ZWbMuw2qW2r6e bf0IDLpKIOoK2lZhGbBa6glJB9H2faI= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769507290; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZDAnxBm956aOF5ZEWN5PM3SfgIASeIOgGwSIT/GymGw=; b=KimfuEVO0LaSFIx1vLjDfszO3hna5+Nma5FK1NDslPhcUrH/gP7YCHp6FkQNCIp4Rrzvxh HcXQNqhZRXxjjgOraT/91ord6ZcUnFisKaRTUxDxWmtCQ3F8UykYDH28W8zxPQ9101jV/z YcM2Z+FHQD7uvJ4j8I97lOIPgKGAtUo= From: Hui Zhu To: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Peter Zijlstra , Miguel Ojeda , Nathan Chancellor , Kees Cook , Tejun Heo , Jeff Xu , mkoutny@suse.com, Jan Hendrik Farr , Christian Brauner , Randy Dunlap , Brian Gerst , Masahiro Yamada , davem@davemloft.net, Jakub Kicinski , Jesper Dangaard Brouer , JP Kobryn , Willem de Bruijn , Jason Xing , Paul Chaignon , Anton Protopopov , Amery Hung , Chen Ridong , Lance Yang , Jiayuan Chen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Hui Zhu , Geliang Tang Subject: [RFC PATCH bpf-next v5 10/12] mm/bpf: Add BPF_F_ALLOW_OVERRIDE support for memcg_bpf_ops Date: Tue, 27 Jan 2026 17:47:35 +0800 Message-ID: <4a1ad099a2db96b92318cb924d2a7b76ee530209.1769506741.git.zhuhui@kylinos.cn> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 6CCCE20003 X-Rspamd-Server: rspam07 X-Stat-Signature: st9mdzeeiytiy735p996fh4dpf5sqaj8 X-HE-Tag: 1769507292-880407 X-HE-Meta: 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 nFxBmg/z Ttpt9IfIWO1FrS4g= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Hui Zhu To allow for more flexible attachment policies in nested cgroup hierarchies, this patch introduces support for the `BPF_F_ALLOW_OVERRIDE` flag for `memcg_bpf_ops`. When a `memcg_bpf_ops` is attached to a cgroup with this flag, it permits child cgroups to attach their own, different `memcg_bpf_ops`, overriding the parent's inherited program. Without this flag, attaching a BPF program to a cgroup that already has one (either directly or via inheritance) will fail. The implementation involves: - Adding a `bpf_ops_flags` field to `struct mem_cgroup`. - During registration (`bpf_memcg_ops_reg`), checking for existing programs and the `BPF_F_ALLOW_OVERRIDE` flag. - During unregistration (`bpf_memcg_ops_unreg`), correctly restoring the parent's BPF program to the cgroup hierarchy. - Ensuring flags are inherited by child cgroups during online events. This change enables complex, multi-level policy enforcement where different subtrees of the cgroup hierarchy can have distinct memory management BPF programs. Signed-off-by: Geliang Tang Signed-off-by: Hui Zhu --- include/linux/memcontrol.h | 1 + mm/bpf_memcontrol.c | 82 ++++++++++++++++++++++++++------------ 2 files changed, 57 insertions(+), 26 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 24c4df864401..98c16e8dcd5b 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -354,6 +354,7 @@ struct mem_cgroup { #ifdef CONFIG_BPF_SYSCALL struct memcg_bpf_ops *bpf_ops; + u32 bpf_ops_flags; #endif struct mem_cgroup_per_node *nodeinfo[]; diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c index e746eb9cbd56..7cd983e350d7 100644 --- a/mm/bpf_memcontrol.c +++ b/mm/bpf_memcontrol.c @@ -213,6 +213,7 @@ void memcontrol_bpf_online(struct mem_cgroup *memcg) goto out; WRITE_ONCE(memcg->bpf_ops, ops); + memcg->bpf_ops_flags = parent_memcg->bpf_ops_flags; /* * If the BPF program implements it, call the online handler to @@ -338,33 +339,19 @@ static int bpf_memcg_ops_init_member(const struct btf_type *t, return 0; } -/** - * clean_memcg_bpf_ops - Clear BPF ops from a memory cgroup hierarchy - * @memcg: Root memory cgroup to start from - * @ops: The specific BPF ops to remove - * - * Walks the cgroup hierarchy and clears bpf_ops for any cgroup that - * matches @ops. - */ -static void clean_memcg_bpf_ops(struct mem_cgroup *memcg, - struct memcg_bpf_ops *ops) -{ - struct mem_cgroup *iter = NULL; - - while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { - if (READ_ONCE(iter->bpf_ops) == ops) - WRITE_ONCE(iter->bpf_ops, NULL); - } -} - static int bpf_memcg_ops_reg(void *kdata, struct bpf_link *link) { struct bpf_struct_ops_link *ops_link = container_of(link, struct bpf_struct_ops_link, link); - struct memcg_bpf_ops *ops = kdata; + struct memcg_bpf_ops *ops = kdata, *old_ops; struct mem_cgroup *memcg, *iter = NULL; int err = 0; + if (ops_link->flags & ~BPF_F_ALLOW_OVERRIDE) { + pr_err("attach only support BPF_F_ALLOW_OVERRIDE\n"); + return -EOPNOTSUPP; + } + memcg = mem_cgroup_get_from_ino(ops_link->cgroup_id); if (!memcg) return -ENOENT; @@ -372,16 +359,41 @@ static int bpf_memcg_ops_reg(void *kdata, struct bpf_link *link) return PTR_ERR(memcg); cgroup_lock(); + + /* + * Check if memcg has bpf_ops and whether it is inherited from + * parent. + * If inherited and BPF_F_ALLOW_OVERRIDE is set, allow override. + */ + old_ops = READ_ONCE(memcg->bpf_ops); + if (old_ops) { + struct mem_cgroup *parent_memcg = parent_mem_cgroup(memcg); + + if (!parent_memcg || + !(memcg->bpf_ops_flags & BPF_F_ALLOW_OVERRIDE) || + READ_ONCE(parent_memcg->bpf_ops) != old_ops) { + err = -EBUSY; + goto unlock_out; + } + } + + /* Check for incompatible bpf_ops in descendants. */ while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { - if (READ_ONCE(iter->bpf_ops)) { - mem_cgroup_iter_break(memcg, iter); + struct memcg_bpf_ops *iter_ops = READ_ONCE(iter->bpf_ops); + + if (iter_ops && iter_ops != old_ops) { + /* cannot override existing bpf_ops of sub-cgroup. */ err = -EBUSY; - break; + goto unlock_out; } + } + + while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { WRITE_ONCE(iter->bpf_ops, ops); + iter->bpf_ops_flags = ops_link->flags; } - if (err) - clean_memcg_bpf_ops(memcg, ops); + +unlock_out: cgroup_unlock(); mem_cgroup_put(memcg); @@ -395,13 +407,31 @@ static void bpf_memcg_ops_unreg(void *kdata, struct bpf_link *link) = container_of(link, struct bpf_struct_ops_link, link); struct memcg_bpf_ops *ops = kdata; struct mem_cgroup *memcg; + struct mem_cgroup *iter; + struct memcg_bpf_ops *parent_bpf_ops = NULL; + u32 parent_bpf_ops_flags = 0; memcg = mem_cgroup_get_from_ino(ops_link->cgroup_id); if (IS_ERR_OR_NULL(memcg)) goto out; cgroup_lock(); - clean_memcg_bpf_ops(memcg, ops); + + /* Get the parent bpf_ops and bpf_ops_flags */ + iter = parent_mem_cgroup(memcg); + if (iter) { + parent_bpf_ops = READ_ONCE(iter->bpf_ops); + parent_bpf_ops_flags = iter->bpf_ops_flags; + } + + iter = NULL; + while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { + if (READ_ONCE(iter->bpf_ops) == ops) { + WRITE_ONCE(iter->bpf_ops, parent_bpf_ops); + iter->bpf_ops_flags = parent_bpf_ops_flags; + } + } + cgroup_unlock(); mem_cgroup_put(memcg); -- 2.43.0