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b=XNpnAMES5OC4zofWEQ9KsfRL5J+zTlmIOclCucf7XWL26Ni9y2W9YOCHeIz4luJxW 6epdhnr0Ye6sH711e47Tlb8kS31HcY0e+SY+dZqW8c30qVDfqDpzZUDcKjrQCHSjD5 IFOoeMtYNvW5gut/7PMoK6wqunXzLTWN86Q4Xl3w= Date: Tue, 28 Apr 2026 15:12:53 -0700 From: Andrew Morton To: Qi Zheng Cc: hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, yosry@kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: Re: [PATCH v2] mm: memcontrol: fix rcu unbalance in get_non_dying_memcg_end() Message-Id: <20260428151253.bdfb08401ebb74c438df0e52@linux-foundation.org> In-Reply-To: <20260428103108.45719-1-qi.zheng@linux.dev> References: <20260428103108.45719-1-qi.zheng@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5B6F240002 X-Rspam-User: X-Stat-Signature: ip6wmzmbgkxy5fbigbju8uzhm9aokno5 X-HE-Tag: 1777414375-824661 X-HE-Meta: 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 m683Ox2O rH3PzVMfa6fPW/FYHEzbSOtbplCBm3jv8AiWbdQIhiVaHuj4N7teqBIWDe75jngibz3ZUOxuP8bQDPSXj2ossHIV4ONtra9eHoUH+DYpcGKiIXsRH2K6oSulz3qHwADgFlJJqX99VEQvkqG7qaXLKLXnPVqvZyYQH2M0A4PQFh5E+GZZyO4aNOQgoltV0q87RrnE9FU9hZiVq36oxnIOLP4BU/FjY1/ygqGvRMy6T84J8mpt/cZtEcQRA/p98Cuv26TDsZdDC5BmhXEUI/XdjTtvQKmiYywPWH8uCCl1d8nc2DKvtKMIUzUGzk6BEzEgju4dpqS1rdVY7v6bR6g7ueyhNRYnLrx2b+k3A Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 28 Apr 2026 18:31:08 +0800 Qi Zheng wrote: > Currently, get_non_dying_memcg_start() and get_non_dying_memcg_end() both > evaluate cgroup_subsys_on_dfl(memory_cgrp_subsys) independently to > determine whether to acquire or release the RCU read lock. Sashiko review (https://sashiko.dev/#/patchset/20260428103108.45719-1-qi.zheng@linux.dev) is correct. mm/memcontrol.c: In function 'mod_memcg_state': mm/memcontrol.c:881:9: error: 'rcu_locked' is used uninitialized [-Werror=uninitialized] 881 | get_non_dying_memcg_end(rcu_locked); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/memcontrol.c:874:14: note: 'rcu_locked' was declared here 874 | bool rcu_locked; | ^~~~~~~~~~ In function 'mod_memcg_lruvec_state', inlined from 'mod_lruvec_state' at mm/memcontrol.c:973:3: mm/memcontrol.c:952:9: error: 'rcu_locked' is used uninitialized [-Werror=uninitialized] 952 | get_non_dying_memcg_end(rcu_locked); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/memcontrol.c:944:14: note: 'rcu_locked' was declared here 944 | bool rcu_locked; | ^~~~~~~~~~ In function 'mod_memcg_state', inlined from 'mem_cgroup_sk_uncharge' at mm/memcontrol.c:5392:2: mm/memcontrol.c:881:9: error: 'rcu_locked' is used uninitialized [-Werror=uninitialized] 881 | get_non_dying_memcg_end(rcu_locked); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/memcontrol.c:874:14: note: 'rcu_locked' was declared here 874 | bool rcu_locked; | ^~~~~~~~~~