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Mon, 21 Sep 2026 09:24:08 +0000 X-Mizu-Trace-ID: d6ffecb1f71c0195 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: Steven Rostedt , Masami Hiramatsu Cc: Ye Liu , Michal Hocko , SJ Park , Lorenzo Stoakes , Oleg Nesterov , akpm@linux-foundation.org, peterz@infradead.org, paulmck@kernel.org, mingo@redhat.com, jpoimboe@kernel.org, mic@digikod.net, tglx@kernel.org, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, rafael@kernel.org, gnoack3000@gmail.com, gourry@gourry.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, will@kernel.org, boqun@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, tony.luck@intel.com, reinette.chatre@intel.com, x86@kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pavel@kernel.org, lance.yang@linux.dev, pmladek@suse.com, longman@redhat.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, mark.rutland@arm.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com Subject: [PATCH v4 11/15] tracing/fgraph: convert process/thread iterator to for_each_process_thread_rculock Date: Mon, 21 Sep 2026 17:20:57 +0800 Message-Id: <20260921092101.89285-12-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260921092101.89285-1-ye.liu@linux.dev> References: <20260921092101.89285-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 9sw1chc5shqbdyi9nyxiopxxd6q5ic9j X-Rspamd-Queue-Id: 89D3D1A0002 X-Rspamd-Server: rspam07 X-HE-Tag: 1789982649-253340 X-HE-Meta: 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 DwnipD84 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined with for_each_process_thread() loop in kernel/trace/fgraph.c with for_each_process_thread_rculock(), which scopes the RCU read lock to the loop body via scoped_guard(rcu). No functional change. Signed-off-by: Ye Liu Acked-by: Michal Hocko Reviewed-by: SJ Park Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Oleg Nesterov Acked-by: Steven Rostedt --- kernel/trace/fgraph.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 40d373d65f9b..f797ce119223 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -1057,11 +1057,10 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) } } - rcu_read_lock(); - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { if (start == end) { ret = -EAGAIN; - goto unlock; + goto free; } if (t->ret_stack == NULL) { @@ -1074,9 +1073,6 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) t->ret_stack = ret_stack_list[start++]; } } - -unlock: - rcu_read_unlock(); free: for (i = start; i < end; i++) kmem_cache_free(fgraph_stack_cachep, ret_stack_list[i]); -- 2.25.1