125 lines
4.0 KiB
Diff
125 lines
4.0 KiB
Diff
From c6ef1b9d671a2002356c0e5fda09dafb37b3dd20 Mon Sep 17 00:00:00 2001
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Message-Id: <c6ef1b9d671a2002356c0e5fda09dafb37b3dd20.1601675153.git.zanussi@kernel.org>
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In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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From: Scott Wood <swood@redhat.com>
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Date: Sat, 12 Oct 2019 01:52:14 -0500
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Subject: [PATCH 309/333] sched: migrate_enable: Use stop_one_cpu_nowait()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz
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[ Upstream commit 6b39a1fa8c53cae08dc03afdae193b7d3a78a173 ]
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migrate_enable() can be called with current->state != TASK_RUNNING.
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Avoid clobbering the existing state by using stop_one_cpu_nowait().
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Since we're stopping the current cpu, we know that we won't get
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past __schedule() until migration_cpu_stop() has run (at least up to
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the point of migrating us to another cpu).
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Signed-off-by: Scott Wood <swood@redhat.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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---
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include/linux/stop_machine.h | 2 ++
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kernel/sched/core.c | 23 +++++++++++++----------
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kernel/stop_machine.c | 7 +++++--
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3 files changed, 20 insertions(+), 12 deletions(-)
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diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
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index 6d3635c86dbe..82fc686ddd9e 100644
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--- a/include/linux/stop_machine.h
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+++ b/include/linux/stop_machine.h
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@@ -26,6 +26,8 @@ struct cpu_stop_work {
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cpu_stop_fn_t fn;
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void *arg;
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struct cpu_stop_done *done;
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+ /* Did not run due to disabled stopper; for nowait debug checks */
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+ bool disabled;
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};
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int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
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diff --git a/kernel/sched/core.c b/kernel/sched/core.c
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index bbde7b29dee2..10c7412bb012 100644
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -990,6 +990,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
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struct migration_arg {
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struct task_struct *task;
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int dest_cpu;
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+ bool done;
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};
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/*
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@@ -1025,6 +1026,11 @@ static int migration_cpu_stop(void *data)
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struct task_struct *p = arg->task;
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struct rq *rq = this_rq();
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struct rq_flags rf;
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+ int dest_cpu = arg->dest_cpu;
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+
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+ /* We don't look at arg after this point. */
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+ smp_mb();
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+ arg->done = true;
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/*
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* The original target CPU might have gone down and we might
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@@ -1047,9 +1053,9 @@ static int migration_cpu_stop(void *data)
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*/
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if (task_rq(p) == rq) {
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if (task_on_rq_queued(p))
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- rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
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+ rq = __migrate_task(rq, &rf, p, dest_cpu);
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else
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- p->wake_cpu = arg->dest_cpu;
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+ p->wake_cpu = dest_cpu;
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}
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rq_unlock(rq, &rf);
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raw_spin_unlock(&p->pi_lock);
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@@ -7317,6 +7323,7 @@ void migrate_enable(void)
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WARN_ON(smp_processor_id() != cpu);
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if (!is_cpu_allowed(p, cpu)) {
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struct migration_arg arg = { p };
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+ struct cpu_stop_work work;
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struct rq_flags rf;
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rq = task_rq_lock(p, &rf);
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@@ -7324,15 +7331,11 @@ void migrate_enable(void)
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arg.dest_cpu = select_fallback_rq(cpu, p);
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task_rq_unlock(rq, p, &rf);
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- preempt_lazy_enable();
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- preempt_enable();
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-
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- sleeping_lock_inc();
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- stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
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- sleeping_lock_dec();
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+ stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
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+ &arg, &work);
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tlb_migrate_finish(p->mm);
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-
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- return;
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+ __schedule(true);
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+ WARN_ON_ONCE(!arg.done && !work.disabled);
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}
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out:
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diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
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index 067cb83f37ea..2d15c0d50625 100644
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--- a/kernel/stop_machine.c
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+++ b/kernel/stop_machine.c
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@@ -86,8 +86,11 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
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enabled = stopper->enabled;
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if (enabled)
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__cpu_stop_queue_work(stopper, work, &wakeq);
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- else if (work->done)
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- cpu_stop_signal_done(work->done);
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+ else {
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+ work->disabled = true;
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+ if (work->done)
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+ cpu_stop_signal_done(work->done);
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+ }
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raw_spin_unlock_irqrestore(&stopper->lock, flags);
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wake_up_q(&wakeq);
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--
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2.17.1
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