From: Steven Rostedt <rostedt@goodmis.org> To: linux-kernel@vger.kernel.org, linux-rt-users <linux-rt-users@vger.kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de>, Carsten Emde <C.Emde@osadl.org>, Sebastian Andrzej Siewior <bigeasy@linutronix.de>, John Kacur <jkacur@redhat.com>, Julia Cartwright <julia@ni.com>, Daniel Wagner <wagi@monom.org>, Tom Zanussi <zanussi@kernel.org>, Scott Wood <swood@redhat.com> Subject: [PATCH RT 24/30] sched: migrate_enable: Use stop_one_cpu_nowait() Date: Thu, 23 Jan 2020 15:39:54 -0500 [thread overview] Message-ID: <20200123203945.766477535@goodmis.org> (raw) In-Reply-To: <20200123203930.646725253@goodmis.org> 4.19.94-rt39-rc2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Scott Wood <swood@redhat.com> [ Upstream commit 6b39a1fa8c53cae08dc03afdae193b7d3a78a173 ] migrate_enable() can be called with current->state != TASK_RUNNING. Avoid clobbering the existing state by using stop_one_cpu_nowait(). Since we're stopping the current cpu, we know that we won't get past __schedule() until migration_cpu_stop() has run (at least up to the point of migrating us to another cpu). Signed-off-by: Scott Wood <swood@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- include/linux/stop_machine.h | 2 ++ kernel/sched/core.c | 23 +++++++++++++---------- kernel/stop_machine.c | 7 +++++-- 3 files changed, 20 insertions(+), 12 deletions(-) diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 6d3635c86dbe..82fc686ddd9e 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -26,6 +26,8 @@ struct cpu_stop_work { cpu_stop_fn_t fn; void *arg; struct cpu_stop_done *done; + /* Did not run due to disabled stopper; for nowait debug checks */ + bool disabled; }; int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e97ac751aad2..e465381b464d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -990,6 +990,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, struct migration_arg { struct task_struct *task; int dest_cpu; + bool done; }; /* @@ -1025,6 +1026,11 @@ static int migration_cpu_stop(void *data) struct task_struct *p = arg->task; struct rq *rq = this_rq(); struct rq_flags rf; + int dest_cpu = arg->dest_cpu; + + /* We don't look at arg after this point. */ + smp_mb(); + arg->done = true; /* * The original target CPU might have gone down and we might @@ -1047,9 +1053,9 @@ static int migration_cpu_stop(void *data) */ if (task_rq(p) == rq) { if (task_on_rq_queued(p)) - rq = __migrate_task(rq, &rf, p, arg->dest_cpu); + rq = __migrate_task(rq, &rf, p, dest_cpu); else - p->wake_cpu = arg->dest_cpu; + p->wake_cpu = dest_cpu; } rq_unlock(rq, &rf); raw_spin_unlock(&p->pi_lock); @@ -7322,6 +7328,7 @@ void migrate_enable(void) WARN_ON(smp_processor_id() != cpu); if (!is_cpu_allowed(p, cpu)) { struct migration_arg arg = { p }; + struct cpu_stop_work work; struct rq_flags rf; rq = task_rq_lock(p, &rf); @@ -7329,15 +7336,11 @@ void migrate_enable(void) arg.dest_cpu = select_fallback_rq(cpu, p); task_rq_unlock(rq, p, &rf); - preempt_lazy_enable(); - preempt_enable(); - - sleeping_lock_inc(); - stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); - sleeping_lock_dec(); + stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop, + &arg, &work); tlb_migrate_finish(p->mm); - - return; + __schedule(true); + WARN_ON_ONCE(!arg.done && !work.disabled); } out: diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 067cb83f37ea..2d15c0d50625 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -86,8 +86,11 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) enabled = stopper->enabled; if (enabled) __cpu_stop_queue_work(stopper, work, &wakeq); - else if (work->done) - cpu_stop_signal_done(work->done); + else { + work->disabled = true; + if (work->done) + cpu_stop_signal_done(work->done); + } raw_spin_unlock_irqrestore(&stopper->lock, flags); wake_up_q(&wakeq); -- 2.24.1
next prev parent reply other threads:[~2020-01-23 20:40 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-23 20:39 [PATCH RT 00/30] Linux 4.19.94-rt39-rc2 Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 01/30] i2c: exynos5: Remove IRQF_ONESHOT Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 02/30] i2c: hix5hd2: " Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 03/30] sched/deadline: Ensure inactive_timer runs in hardirq context Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 04/30] thermal/x86_pkg_temp: make pkg_temp_lock a raw spinlock Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 05/30] dma-buf: Use seqlock_t instread disabling preemption Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 06/30] KVM: arm/arm64: Let the timer expire in hardirq context on RT Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 07/30] x86: preempt: Check preemption level before looking at lazy-preempt Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 08/30] hrtimer: Use READ_ONCE to access timer->base in hrimer_grab_expiry_lock() Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 09/30] hrtimer: Dont grab the expiry lock for non-soft hrtimer Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 10/30] hrtimer: Prevent using hrtimer_grab_expiry_lock() on migration_base Steven Rostedt 2020-04-27 13:10 ` Rasmus Villemoes 2020-04-27 19:06 ` Steven Rostedt 2020-04-27 19:26 ` Tom Zanussi 2020-04-28 6:51 ` Rasmus Villemoes 2020-04-28 7:03 ` Rasmus Villemoes 2020-04-28 12:59 ` Tom Zanussi 2020-04-28 13:07 ` Rasmus Villemoes 2020-04-28 13:43 ` Tom Zanussi 2020-01-23 20:39 ` [PATCH RT 11/30] hrtimer: Add a missing bracket and hide `migration_base on !SMP Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 12/30] posix-timers: Unlock expiry lock in the early return Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 14/30] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 15/30] sched: Remove dead __migrate_disabled() check Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 16/30] sched: migrate disable: Protect cpus_ptr with lock Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 17/30] lib/smp_processor_id: Dont use cpumask_equal() Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 18/30] futex: Make the futex_hash_bucket spinlock_t again and bring back its old state Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 19/30] locking/rtmutex: Clean ->pi_blocked_on in the error case Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 20/30] lib/ubsan: Dont seralize UBSAN report Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 21/30] kmemleak: Change the lock of kmemleak_object to raw_spinlock_t Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 22/30] sched: migrate_enable: Use select_fallback_rq() Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 23/30] sched: Lazy migrate_disable processing Steven Rostedt 2020-01-23 20:39 ` Steven Rostedt [this message] 2020-01-23 20:39 ` [PATCH RT 25/30] Revert "ARM: Initialize split page table locks for vector page" Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 26/30] locking: Make spinlock_t and rwlock_t a RCU section on RT Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 27/30] sched/core: migrate_enable() must access takedown_cpu_task on !HOTPLUG_CPU Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 28/30] lib/smp_processor_id: Adjust check_preemption_disabled() Steven Rostedt 2020-01-23 20:39 ` [PATCH RT 29/30] sched: migrate_enable: Busy loop until the migration request is completed Steven Rostedt 2020-01-23 20:40 ` [PATCH RT 30/30] Linux 4.19.94-rt39-rc2 Steven Rostedt
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