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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9397fb59c72sm907982585a.26.2026.09.07.08.53.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Sep 2026 08:53:54 -0700 (PDT) Date: Mon, 7 Sep 2026 11:53:51 -0400 From: Gregory Price To: Ye Liu Cc: Thomas Gleixner , Peter Zijlstra , "Rafael J. Wysocki" , Andrew Morton , Ingo Molnar , Will Deacon , Boqun Feng , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Juri Lelli , Vincent Guittot , Steven Rostedt , Masami Hiramatsu , Josh Poimboeuf , Ye Liu , Michal Hocko , mic@digikod.net, oleg@redhat.com, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, gnoack3000@gmail.com, ljs@kernel.org, sj@kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, 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, 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 Subject: Re: [PATCH v2 5/8] kernel: convert process/thread iterators to for_each_*_rculock Message-ID: References: <20260907081334.1152889-1-ye.liu@linux.dev> <20260907081334.1152889-6-ye.liu@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260907081334.1152889-6-ye.liu@linux.dev> X-Stat-Signature: 7r57nm1xyy8qjgmtioxjrkgec8j14khu X-Rspamd-Queue-Id: D0CBFC0008 X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1788796435-713380 X-HE-Meta: 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 KHciAhIF 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote: > From: Ye Liu > > Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu) > pairs combined with for_each_process(), for_each_thread() and > for_each_process_thread() loops across kernel/ with the > for_each_*_rculock() macros, which scope the RCU read lock to the > loop body via scoped_guard(rcu). > > No functional change. > > Signed-off-by: Ye Liu > Acked-by: Michal Hocko Question below > diff --git a/kernel/hung_task.c b/kernel/hung_task.c > index 6fcc94ce4ca9..73a5ad3be9a8 100644 > --- a/kernel/hung_task.c > +++ b/kernel/hung_task.c > @@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > return; > > this_round_count = 0; > - rcu_read_lock(); > - for_each_process_thread(g, t) { > + for_each_process_thread_rculock(g, t) { > if (!max_count--) > - goto unlock; > + goto out; ... snip ... > - unlock: > - rcu_read_unlock(); > - > +out: > if (!this_round_count) > return; > The sunken rcu_read_lock()/unlock() + scoped_guard usage makes this goto at a minimum very confusing, if not actually broken. Are we sure this isn't broken as-written? Generally we don't mix cleanup and goto for exactly this reason. ~Gregory