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Howlett" Cc: Andrew Morton , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Geert Uytterhoeven , "Paul E. McKenney" , Christophe Leroy , Andreas Schwab , Matthew Wilcox , Peng Zhang , Ingo Molnar , Juri Lelli , Vincent Guittot , "Mike Rapoport (IBM)" , Vlastimil Babka Subject: Re: [PATCH] init/main: Clear boot task idle flag Message-ID: <20230913135246.GH692@noisy.programming.kicks-ass.net> References: <20230913005647.1534747-1-Liam.Howlett@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230913005647.1534747-1-Liam.Howlett@oracle.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 159D21C001C X-Stat-Signature: 9go7yh6p8miabn1mgeormfqikzkbt6z7 X-Rspam-User: X-HE-Tag: 1694613179-998068 X-HE-Meta: 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 IizUOgxW cGfkmiy4NHsuvM+HoFIIEm3GvwJPL2Tn6Z+YMGva/e1iOcaQvcKvpPf/pu/fG92TzPYHVYhBqVoDwioHN3u+blilUHjJXXLyE4tX70N9p8C/d3uyxeFHm6ptv7AA+hTFvvUlNGt9mhL/qPL0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 12, 2023 at 08:56:47PM -0400, Liam R. Howlett wrote: > diff --git a/init/main.c b/init/main.c > index ad920fac325c..f74772acf612 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -696,7 +696,7 @@ noinline void __ref __noreturn rest_init(void) > */ > rcu_read_lock(); > tsk = find_task_by_pid_ns(pid, &init_pid_ns); > - tsk->flags |= PF_NO_SETAFFINITY; > + tsk->flags |= PF_NO_SETAFFINITY | PF_IDLE; > set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id())); > rcu_read_unlock(); > Hmm, isn't that pid-1 you're setting PF_IDLE on? The task becoming idle is 'current' at this point, see the cpu_startup_entry() call below. Would not something like so be the right thing? diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2299a5cfbfb9..802551e0009b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9269,7 +9269,7 @@ void __init init_idle(struct task_struct *idle, int cpu) * PF_KTHREAD should already be set at this point; regardless, make it * look like a proper per-CPU kthread. */ - idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY; + idle->flags |= PF_KTHREAD | PF_NO_SETAFFINITY; kthread_set_per_cpu(idle, cpu); #ifdef CONFIG_SMP diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 342f58a329f5..5007b25c5bc6 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,6 +373,7 @@ EXPORT_SYMBOL_GPL(play_idle_precise); void cpu_startup_entry(enum cpuhp_state state) { + current->flags |= PF_IDLE; arch_cpu_idle_prepare(); cpuhp_online_idle(state); while (1)