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Tue, 24 Mar 2026 02:10:54 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4871174f2desm44785325e9.9.2026.03.24.02.10.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 02:10:53 -0700 (PDT) Date: Tue, 24 Mar 2026 12:10:49 +0300 From: Dan Carpenter To: oe-kbuild@lists.linux.dev, David Carlier , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Qi Zheng Cc: lkp@intel.com, oe-kbuild-all@lists.linux.dev, Linux Memory Management List , David Carlier , stable@vger.kernel.org Subject: Re: [PATCH] mm/memcontrol: fix obj_cgroup leak in mem_cgroup_css_online() error path Message-ID: <202603241635.qNXDPwjs-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260322164943.37460-1-devnexen@gmail.com> X-Rspam-User: X-Stat-Signature: dybu8hcjp5u7hhzda59hbojou9dpxc7w X-Rspamd-Queue-Id: E4CBC80011 X-Rspamd-Server: rspam09 X-HE-Tag: 1774343455-329912 X-HE-Meta: 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 aC2DoaW7 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi David, kernel test robot noticed the following build warnings: url: https://github.com/intel-lab-lkp/linux/commits/David-Carlier/mm-memcontrol-fix-obj_cgroup-leak-in-mem_cgroup_css_online-error-path/20260324-010357 base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20260322164943.37460-1-devnexen%40gmail.com patch subject: [PATCH] mm/memcontrol: fix obj_cgroup leak in mem_cgroup_css_online() error path config: arm64-randconfig-r072-20260324 (https://download.01.org/0day-ci/archive/20260324/202603241635.qNXDPwjs-lkp@intel.com/config) compiler: aarch64-linux-gcc (GCC) 14.3.0 smatch: v0.5.0-9004-gb810ac53 If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Reported-by: Dan Carpenter | Closes: https://lore.kernel.org/r/202603241635.qNXDPwjs-lkp@intel.com/ smatch warnings: mm/memcontrol.c:4180 mem_cgroup_css_online() warn: variable dereferenced before check 'pn' (see line 4176) vim +/pn +4180 mm/memcontrol.c 6f0df8e16eb543 Johannes Weiner 2023-08-23 4168 * regular ID destruction during offlining. 6f0df8e16eb543 Johannes Weiner 2023-08-23 4169 */ e77786b4682e69 Shakeel Butt 2025-12-25 4170 xa_store(&mem_cgroup_private_ids, memcg->id.id, memcg, GFP_KERNEL); 6f0df8e16eb543 Johannes Weiner 2023-08-23 4171 2f7dd7a4100ad4 Johannes Weiner 2014-10-02 4172 return 0; 098fad3e1621cb Qi Zheng 2026-03-05 4173 free_objcg: 098fad3e1621cb Qi Zheng 2026-03-05 4174 for_each_node(nid) { 098fad3e1621cb Qi Zheng 2026-03-05 4175 struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid]; 59f75a1877fbf7 David Carlier 2026-03-22 @4176 objcg = rcu_replace_pointer(pn->objcg, NULL, true); ^^^^^^^^^ Dereference 59f75a1877fbf7 David Carlier 2026-03-22 4177 if (objcg) 59f75a1877fbf7 David Carlier 2026-03-22 4178 percpu_ref_kill(&objcg->refcnt); 098fad3e1621cb Qi Zheng 2026-03-05 4179 4a2f95f5c79e02 Qi Zheng 2026-03-09 @4180 if (pn && pn->orig_objcg) { ^^ Checked too late. 098fad3e1621cb Qi Zheng 2026-03-05 4181 obj_cgroup_put(pn->orig_objcg); 4a2f95f5c79e02 Qi Zheng 2026-03-09 4182 /* 02b5fc7885d9f8 Andrew Morton 2026-03-09 4183 * Reset pn->orig_objcg to NULL to prevent 02b5fc7885d9f8 Andrew Morton 2026-03-09 4184 * obj_cgroup_put() from being called again in 02b5fc7885d9f8 Andrew Morton 2026-03-09 4185 * __mem_cgroup_free(). 4a2f95f5c79e02 Qi Zheng 2026-03-09 4186 */ 4a2f95f5c79e02 Qi Zheng 2026-03-09 4187 pn->orig_objcg = NULL; 4a2f95f5c79e02 Qi Zheng 2026-03-09 4188 } 098fad3e1621cb Qi Zheng 2026-03-05 4189 } a0dd8b1942f5bf Muchun Song 2026-03-05 4190 free_shrinker_info(memcg); da0efe30944476 Muchun Song 2022-03-22 4191 offline_kmem: da0efe30944476 Muchun Song 2022-03-22 4192 memcg_offline_kmem(memcg); e77786b4682e69 Shakeel Butt 2025-12-25 4193 mem_cgroup_private_id_remove(memcg); da0efe30944476 Muchun Song 2022-03-22 4194 return -ENOMEM; 8cdea7c0545426 Balbir Singh 2008-02-07 4195 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki