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h=In-Reply-To:References:Subject:From:To:Cc:Date:From; b=F4nwAcHuuogXfFilu9ZLMVOGjf65Q6kn1NjG9xHyDQjxcKw8mechHmV/2UoKNz9eX yJdAhjb8zATwBjMJEYORx1exA7ugxyGbFhiybcChfKths7LymkhEC8uUfdVAqQ+Cnk /o1gx/rRVWYfwSVJFVNyAAXiwr1O1zLo//uJpXLFBwn0PcbFklSM0Rpv0xAMtPn4j2 8YndREmYbf+pnDgoHlMqu3Gq3NgBZT0dv6A66E1CQjJOxJ8Zib3HFLfoE1BkDFnBx4 NoGBDqusxbltNqeA4KQjr/pVHZpn9vRTit7GBPlVxmcI/2vSzgNvZoaVTOpUcKsHcM nAuh2eNSimJrg== Content-Type: multipart/mixed; boundary="===============7572374899106477181==" MIME-Version: 1.0 Message-Id: In-Reply-To: <9f072e53f79ceaea43e3730476494517e453530a.1769157382.git.zhuhui@kylinos.cn> References: <9f072e53f79ceaea43e3730476494517e453530a.1769157382.git.zhuhui@kylinos.cn> Subject: Re: [RFC PATCH bpf-next v3 10/12] mm/bpf: Add BPF_F_ALLOW_OVERRIDE support for memcg_bpf_ops From: bot+bpf-ci@kernel.org To: hui.zhu@linux.dev, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, shuah@kernel.org, peterz@infradead.org, ojeda@kernel.org, nathan@kernel.org, kees@kernel.org, tj@kernel.org, jeffxu@chromium.org, mkoutny@suse.com, kernel@jfarr.cc, brauner@kernel.org, rdunlap@infradead.org, brgerst@gmail.com, masahiroy@kernel.org, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, inwardvessel@gmail.com, willemb@google.com, kerneljasonxing@gmail.com, paul.chaignon@gmail.com, a.s.protopopov@gmail.com, ameryhung@gmail.com, chenridong@huaweicloud.com, lance.yang@linux.dev, jiayuan.chen@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, linu@kvack.org, x-kselftest@vger.kernel.org Cc: zhuhui@kylinos.cn,geliang@kernel.org,ast@kernel.org,andrii@kernel.org,daniel@iogearbox.net,martin.lau@kernel.org,eddyz87@gmail.com,yonghong.song@linux.dev,clm@meta.com,ihor.solodrai@linux.dev Date: Fri, 23 Jan 2026 09:29:42 +0000 (UTC) X-Rspamd-Server: rspam11 X-Stat-Signature: tn4fkxrwkpgt14txew5c4dbonagy97nd X-Rspam-User: X-Rspamd-Queue-Id: 40D8CC0002 X-HE-Tag: 1769160585-387632 X-HE-Meta: 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 jOlgtPd7 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 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: --===============7572374899106477181== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit > diff --git a/mm/bpf_memcontrol.c b/mm/bpf_memcontrol.c > index 415e3c59b6a6..0ded1fdd0de8 100644 > --- a/mm/bpf_memcontrol.c > +++ b/mm/bpf_memcontrol.c [ ... ] > 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 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(); > + > + 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) > + goto busy_out; > + if (READ_ONCE(iter->bpf_ops) != > + READ_ONCE(memcg->bpf_ops)) > + goto busy_out; > + } else { > +busy_out: > + err = -EBUSY; > + goto unlock_out; > + } > + } > + > while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { ^^^^ When the override check passes (all conditions at lines 363-377 are met), iter is set to parent_mem_cgroup(memcg) but is never reset to NULL before this loop. Should iter be reset to NULL here? The mem_cgroup_iter() function expects prev (iter) to be either NULL or a previous result from iterating within memcg's descendants. When iter points to memcg's parent, the iteration will not correctly traverse memcg's subtree since parent is outside that subtree. For comparison, bpf_memcg_ops_unreg() correctly resets iter to NULL before its loop: > + iter = NULL; > + while ((iter = mem_cgroup_iter(memcg, iter, NULL))) { > if (READ_ONCE(iter->bpf_ops)) { > - mem_cgroup_iter_break(memcg, iter); > - err = -EBUSY; > - break; > + /* cannot override existing bpf_ops of sub-cgroup. */ > + continue; > } > WRITE_ONCE(iter->bpf_ops, ops); > + iter->bpf_ops_flags = ops_link->flags; > } [ ... ] --- AI reviewed your patch. Please fix the bug or email reply why it's not a bug. See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21280790825 --===============7572374899106477181==--