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Subject: Re: [PATCH v2 7/7] sched: Change task_struct::state
To:     Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>
Cc:     Borislav Petkov <bp@alien8.de>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, Jens Axboe <axboe@kernel.dk>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Douglas Anderson <dianders@chromium.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Pavel Machek <pavel@ucw.cz>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        John Stultz <john.stultz@linaro.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
References: <20210611082810.970791107@infradead.org>
 <20210611082838.550736351@infradead.org>
From:   Daniel Bristot de Oliveira <bristot@redhat.com>
Message-ID: <baf4b8d9-5801-45a8-d92a-be45a918e855@redhat.com>
Date:   Wed, 16 Jun 2021 15:24:10 +0200
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On 6/11/21 10:28 AM, Peter Zijlstra wrote:
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -348,10 +348,10 @@ static void task_non_contending(struct t
>  	if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
>  		if (dl_task(p))
>  			sub_running_bw(dl_se, dl_rq);
> -		if (!dl_task(p) || p->state == TASK_DEAD) {
> +		if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
>  			struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
>  
> -			if (p->state == TASK_DEAD)
> +			if (READ_ONCE(p->__state) == TASK_DEAD)
>  				sub_rq_bw(&p->dl, &rq->dl);
>  			raw_spin_lock(&dl_b->lock);
>  			__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
> @@ -1355,10 +1355,10 @@ static enum hrtimer_restart inactive_tas
>  	sched_clock_tick();
>  	update_rq_clock(rq);
>  
> -	if (!dl_task(p) || p->state == TASK_DEAD) {
> +	if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
>  		struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
>  
> -		if (p->state == TASK_DEAD && dl_se->dl_non_contending) {
> +		if (READ_ONCE(p->__state) == TASK_DEAD && dl_se->dl_non_contending) {
>  			sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
>  			sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
>  			dl_se->dl_non_contending = 0;
> @@ -1722,7 +1722,7 @@ static void migrate_task_rq_dl(struct ta
>  {
>  	struct rq *rq;
>  
> -	if (p->state != TASK_WAKING)
> +	if (READ_ONCE(p->__state) != TASK_WAKING)
>  		return;
>  
>  	rq = task_rq(p);

Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>

Feel free to add it to the other patches as well.

Thanks!
-- Daniel