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 E82BEC88E7B for ; Mon, 26 Jan 2026 09:07:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5D02E6B0092; Mon, 26 Jan 2026 04:07:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5AEA66B0098; Mon, 26 Jan 2026 04:07:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4B1616B0099; Mon, 26 Jan 2026 04:07:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 382766B0092 for ; Mon, 26 Jan 2026 04:07:26 -0500 (EST) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id DDFDEC2678 for ; Mon, 26 Jan 2026 09:07:25 +0000 (UTC) X-FDA: 84373536450.03.75E6E80 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) by imf06.hostedemail.com (Postfix) with ESMTP id 26544180006 for ; Mon, 26 Jan 2026 09:07:23 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="lTtXD/LO"; spf=pass (imf06.hostedemail.com: domain of hui.zhu@linux.dev designates 91.218.175.189 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=1769418444; 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=k0Dc6FifkDwPpG09rd3OftsrldqK8TRlWZhlATE0DkY=; b=GfOU647HpPLu27ns27i94MqKsAVpXr1Fp21xAY4aTEV88BvlmhFjPHhrnsS3QvVD3pqI+a 4QZt9jlFhWWSYji43Yom7Zr2gebGCU9FZZ6Wwz2taCtPtOPmm/X5ygh3fwFQb9j1n+EtWX ISOi3d+Xf41/UjBsnRT1x7CKsAFLiZI= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="lTtXD/LO"; spf=pass (imf06.hostedemail.com: domain of hui.zhu@linux.dev designates 91.218.175.189 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=1769418444; a=rsa-sha256; cv=none; b=RbUAqlVaw5aSggH47y7U3DP8n/g78dpNWwuC1e2VOXWqUc7M3nb1NjwwJyEQtn4qtu4vNE rk37wNHqrHDWwObGr8JpmqyXgaMz9O1hlM5Mw1sO7HfXQbcsNaKJnm2aG+fTpRD7gWtb+S URS19Av1L/uaZTrl2alIyjSl6vCbryo= 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=1769418442; 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=k0Dc6FifkDwPpG09rd3OftsrldqK8TRlWZhlATE0DkY=; b=lTtXD/LOh3+IIxcd+dM/dMSFWAaGTq5gjHRoiDFFdavMxM7L6EGNrEf0lErtM5ghv2fBme Ip0pPMjC2i51hLQLRC/Dg2BHUOvqmmxQ5KffNQlcavmQn77TLycm+sAIeSV4UoSkeaPraa DrmsMzn84Btk59jaJ2L8npT332it7K4= 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 v4 10/12] mm/bpf: Add BPF_F_ALLOW_OVERRIDE support for memcg_bpf_ops Date: Mon, 26 Jan 2026 17:06:29 +0800 Message-ID: <443511ca5d83a01d9f7f14c9548dea41ea485aab.1769417588.git.zhuhui@kylinos.cn> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 26544180006 X-Stat-Signature: qsqkpcwogouxi3e7qfxswtmqy5p693c8 X-Rspam-User: X-HE-Tag: 1769418443-848480 X-HE-Meta: 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 ekO4rlri TnOWHRFpHJR/WsYIKifEfd9kyMkF2xQ8hFExA0434+0Z/d6Yu+e2IRe997h6d6Ql4rByTJD09+KwMssIzi/Ay3vO48JSw5Bjhzql/939skrS80ptSRJ5k8aF8m8ZBqtCnR906fHxBzAzmGsfaff5uR2uaBLVRUL3KQrtsL7xhFNmta22v/BQChw2sp4F3s2elPg7sROvVjgseJD8M53fejWOL9mLwQKMPlmiDNVFQz6PbvRg8YZ31vdVq9FPZXWoZFZUmbjQbwO5o8GfXCEC1fK4vjxP1E59vIo4MYtmnMDGRQzE= 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 | 83 ++++++++++++++++++++++++-------------- 2 files changed, 53 insertions(+), 31 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 1083be5d0362..6e15da44ba35 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 20c5c3552ce3..756a7d4eb4e3 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 @@ -340,52 +341,54 @@ static int bpf_memcg_ops_init_member(const struct btf_type *t, return 0; } -/** - * clean_memcg_bpf_ops - Detach BPF programs from a cgroup hierarchy. - * @memcg: The root of the cgroup hierarchy to clean. - * @ops: The specific ops struct to detach. If NULL, detach any ops. - * - * Iterates through all descendant cgroups of @memcg (including itself) - * and clears their bpf_ops pointer. This is used when a BPF program - * is detached or if attachment fails midway. - */ -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 (ops) { - if (!WARN_ON(READ_ONCE(iter->bpf_ops) != ops)) - WRITE_ONCE(iter->bpf_ops, NULL); - } else - 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, *parent_ops = NULL; 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 (IS_ERR_OR_NULL(memcg)) return PTR_ERR(memcg); cgroup_lock(); - while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { - if (READ_ONCE(iter->bpf_ops)) { - mem_cgroup_iter_break(memcg, iter); + + if (READ_ONCE(memcg->bpf_ops)) { + /* Check if bpf_ops of the parent is BPF_F_ALLOW_OVERRIDE. */ + if (memcg->bpf_ops_flags & BPF_F_ALLOW_OVERRIDE) { + iter = parent_mem_cgroup(memcg); + if (!iter || READ_ONCE(iter->bpf_ops) != + READ_ONCE(memcg->bpf_ops)) + goto busy_out; + + parent_ops = READ_ONCE(memcg->bpf_ops); + } else { +busy_out: err = -EBUSY; - break; + goto unlock_out; + } + } + + iter = NULL; + while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { + struct memcg_bpf_ops *iter_ops = READ_ONCE(iter->bpf_ops); + + if (iter_ops && iter_ops != parent_ops) { + /* cannot override existing bpf_ops of sub-cgroup. */ + continue; } WRITE_ONCE(iter->bpf_ops, ops); + iter->bpf_ops_flags = ops_link->flags; } - if (err) - clean_memcg_bpf_ops(memcg, NULL); + +unlock_out: cgroup_unlock(); mem_cgroup_put(memcg); @@ -399,13 +402,31 @@ 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