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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9399429b97esm677101585a.29.2026.09.07.14.05.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Sep 2026 14:05:19 -0700 (PDT) Date: Mon, 7 Sep 2026 17:05:15 -0400 From: Gregory Price To: Oleg Nesterov Cc: Ye Liu , 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, 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: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DABBC140008 X-Stat-Signature: ewfbzp6hcaoaf9iprjb7a4gu5u5jadgi X-HE-Tag: 1788815120-913348 X-HE-Meta: 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 iMRVdeRS cAhkC2Sxwqc+TIWZ84FQxf4So8S2wqjkcLw0NiRs9FzxZFdlWCz5m3/TLwliRFna2x14HmItC9a3/MkYYsf5ZU4jMgPCOFDf0JXAAH8vbHN7tncMmQswOOa64aI3lRjU2Mse3N/vknPNRB3gCDqlnnZlLtToqk3MxEY/5yKSAKsnY7Soiw87z8FlBYBC6qwIfQEl8j8WBgiQfsS/xeEOTrJFQLmbbOd6uI1nhTjIQgMfWycFSbVfj+yEREMU4rD+lfoZHS8QcwGZbYJKeAY9arJG6nD4pkVc+g8YyJ6y+kVGSSJivm6NnsrHpttYCUkrt9DD9/oHQlpgT4iNqAHREGXyZNadjKo4PvbIrRH9Gn+82zflcW08Cp9/5UTLv7vHcYV05FavBJkVfU1Osrog8WLlMN59C4MaW+6DeqYz8ghKnKodVVOAWvOTwOrahArlYPSbQ83ABi7jVyvQ= 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 07:57:15PM +0200, Oleg Nesterov wrote: > On 09/07, Gregory Price wrote: > > > > On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote: > > > --- 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. > > I am afraid I misunderstood you concerns... > This might be my - admittedly shallow - understanding of scoped_guard, but does scoped guard handle goto correctly? On the surface it looks like it would skip the unlock entirely. That is what i mean by "at a minimum very confusing, if not broken" and why it's generally discouraged to mix cleanup.h and goto. ~Gregory