Adding debian version 4.19.249-2.debian/4.19.249-2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 616 insertions, 0 deletions

diff --git a/debian/patches-rt/0308-sched-Lazy-migrate_disable-processing.patch b/debian/patches-rt/0308-sched-Lazy-migrate_disable-processing.patch
new file mode 100644
index 000000000..973b6e870
--- /dev/null
+++ b/debian/patches-rt/0308-sched-Lazy-migrate_disable-processing.patch
@@ -0,0 +1,616 @@
+From 34b182c6f6606c5a02a3ddea15356251ca28093b Mon Sep 17 00:00:00 2001
+From: Scott Wood <swood@redhat.com>
+Date: Sat, 12 Oct 2019 01:52:13 -0500
+Subject: [PATCH 308/347] sched: Lazy migrate_disable processing
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+[ Upstream commit 425c5b38779a860062aa62219dc920d374b13c17 ]
+
+Avoid overhead on the majority of migrate disable/enable sequences by
+only manipulating scheduler data (and grabbing the relevant locks) when
+the task actually schedules while migrate-disabled.  A kernel build
+showed around a 10% reduction in system time (with CONFIG_NR_CPUS=512).
+
+Instead of cpuhp_pin_lock, CPU hotplug is handled by keeping a per-CPU
+count of the number of pinned tasks (including tasks which have not
+scheduled in the migrate-disabled section); takedown_cpu() will
+wait until that reaches zero (confirmed by take_cpu_down() in stop
+machine context to deal with races) before migrating tasks off of the
+cpu.
+
+To simplify synchronization, updating cpus_mask is no longer deferred
+until migrate_enable().  This lets us not have to worry about
+migrate_enable() missing the update if it's on the fast path (didn't
+schedule during the migrate disabled section).  It also makes the code
+a bit simpler and reduces deviation from mainline.
+
+While the main motivation for this is the performance benefit, lazy
+migrate disable also eliminates the restriction on calling
+migrate_disable() while atomic but leaving the atomic region prior to
+calling migrate_enable() -- though this won't help with local_bh_disable()
+(and thus rcutorture) unless something similar is done with the recently
+added local_lock.
+
+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/cpu.h    |   4 -
+ include/linux/sched.h  |  11 +--
+ init/init_task.c       |   4 +
+ kernel/cpu.c           | 103 +++++++++--------------
+ kernel/sched/core.c    | 182 +++++++++++++++++------------------------
+ kernel/sched/sched.h   |   4 +
+ lib/smp_processor_id.c |   3 +
+ 7 files changed, 129 insertions(+), 182 deletions(-)
+
+diff --git a/include/linux/cpu.h b/include/linux/cpu.h
+index e67645924404..87347ccbba0c 100644
+--- a/include/linux/cpu.h
++++ b/include/linux/cpu.h
+@@ -118,8 +118,6 @@ extern void cpu_hotplug_disable(void);
+ extern void cpu_hotplug_enable(void);
+ void clear_tasks_mm_cpumask(int cpu);
+ int cpu_down(unsigned int cpu);
+-extern void pin_current_cpu(void);
+-extern void unpin_current_cpu(void);
+ 
+ #else /* CONFIG_HOTPLUG_CPU */
+ 
+@@ -131,8 +129,6 @@ static inline int  cpus_read_trylock(void) { return true; }
+ static inline void lockdep_assert_cpus_held(void) { }
+ static inline void cpu_hotplug_disable(void) { }
+ static inline void cpu_hotplug_enable(void) { }
+-static inline void pin_current_cpu(void) { }
+-static inline void unpin_current_cpu(void) { }
+ 
+ #endif	/* !CONFIG_HOTPLUG_CPU */
+ 
+diff --git a/include/linux/sched.h b/include/linux/sched.h
+index e567fe2d7058..65069db8923c 100644
+--- a/include/linux/sched.h
++++ b/include/linux/sched.h
+@@ -227,6 +227,8 @@ extern void io_schedule_finish(int token);
+ extern long io_schedule_timeout(long timeout);
+ extern void io_schedule(void);
+ 
++int cpu_nr_pinned(int cpu);
++
+ /**
+  * struct prev_cputime - snapshot of system and user cputime
+  * @utime: time spent in user mode
+@@ -670,16 +672,13 @@ struct task_struct {
+ 	cpumask_t			cpus_mask;
+ #if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+ 	int				migrate_disable;
+-	int				migrate_disable_update;
+-	int				pinned_on_cpu;
++	bool				migrate_disable_scheduled;
+ # ifdef CONFIG_SCHED_DEBUG
+-	int				migrate_disable_atomic;
++	int				pinned_on_cpu;
+ # endif
+-
+ #elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+ # ifdef CONFIG_SCHED_DEBUG
+ 	int				migrate_disable;
+-	int				migrate_disable_atomic;
+ # endif
+ #endif
+ #ifdef CONFIG_PREEMPT_RT_FULL
+@@ -2058,4 +2057,6 @@ static inline void rseq_syscall(struct pt_regs *regs)
+ 
+ #endif
+ 
++extern struct task_struct *takedown_cpu_task;
++
+ #endif
+diff --git a/init/init_task.c b/init/init_task.c
+index 634becebd713..45b84137c4b3 100644
+--- a/init/init_task.c
++++ b/init/init_task.c
+@@ -80,6 +80,10 @@ struct task_struct init_task
+ 	.cpus_ptr	= &init_task.cpus_mask,
+ 	.cpus_mask	= CPU_MASK_ALL,
+ 	.nr_cpus_allowed= NR_CPUS,
++#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE) && \
++    defined(CONFIG_SCHED_DEBUG)
++	.pinned_on_cpu	= -1,
++#endif
+ 	.mm		= NULL,
+ 	.active_mm	= &init_mm,
+ 	.restart_block	= {
+diff --git a/kernel/cpu.c b/kernel/cpu.c
+index c84a93f84164..edd4fd8da726 100644
+--- a/kernel/cpu.c
++++ b/kernel/cpu.c
+@@ -77,11 +77,6 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
+ 	.fail = CPUHP_INVALID,
+ };
+ 
+-#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PREEMPT_RT_FULL)
+-static DEFINE_PER_CPU(struct rt_rw_lock, cpuhp_pin_lock) = \
+-	__RWLOCK_RT_INITIALIZER(cpuhp_pin_lock);
+-#endif
+-
+ #if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
+ static struct lockdep_map cpuhp_state_up_map =
+ 	STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);
+@@ -288,57 +283,6 @@ static int cpu_hotplug_disabled;
+ 
+ #ifdef CONFIG_HOTPLUG_CPU
+ 
+-/**
+- * pin_current_cpu - Prevent the current cpu from being unplugged
+- */
+-void pin_current_cpu(void)
+-{
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	struct rt_rw_lock *cpuhp_pin;
+-	unsigned int cpu;
+-	int ret;
+-
+-again:
+-	cpuhp_pin = this_cpu_ptr(&cpuhp_pin_lock);
+-	ret = __read_rt_trylock(cpuhp_pin);
+-	if (ret) {
+-		current->pinned_on_cpu = smp_processor_id();
+-		return;
+-	}
+-	cpu = smp_processor_id();
+-	preempt_lazy_enable();
+-	preempt_enable();
+-
+-	sleeping_lock_inc();
+-	__read_rt_lock(cpuhp_pin);
+-	sleeping_lock_dec();
+-
+-	preempt_disable();
+-	preempt_lazy_disable();
+-	if (cpu != smp_processor_id()) {
+-		__read_rt_unlock(cpuhp_pin);
+-		goto again;
+-	}
+-	current->pinned_on_cpu = cpu;
+-#endif
+-}
+-
+-/**
+- * unpin_current_cpu - Allow unplug of current cpu
+- */
+-void unpin_current_cpu(void)
+-{
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	struct rt_rw_lock *cpuhp_pin = this_cpu_ptr(&cpuhp_pin_lock);
+-
+-	if (WARN_ON(current->pinned_on_cpu != smp_processor_id()))
+-		cpuhp_pin = per_cpu_ptr(&cpuhp_pin_lock, current->pinned_on_cpu);
+-
+-	current->pinned_on_cpu = -1;
+-	__read_rt_unlock(cpuhp_pin);
+-#endif
+-}
+-
+ DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
+ 
+ void cpus_read_lock(void)
+@@ -932,6 +876,15 @@ static int take_cpu_down(void *_param)
+ 	int err, cpu = smp_processor_id();
+ 	int ret;
+ 
++#ifdef CONFIG_PREEMPT_RT_BASE
++	/*
++	 * If any tasks disabled migration before we got here,
++	 * go back and sleep again.
++	 */
++	if (cpu_nr_pinned(cpu))
++		return -EAGAIN;
++#endif
++
+ 	/* Ensure this CPU doesn't handle any more interrupts. */
+ 	err = __cpu_disable();
+ 	if (err < 0)
+@@ -959,11 +912,10 @@ static int take_cpu_down(void *_param)
+ 	return 0;
+ }
+ 
++struct task_struct *takedown_cpu_task;
++
+ static int takedown_cpu(unsigned int cpu)
+ {
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	struct rt_rw_lock *cpuhp_pin = per_cpu_ptr(&cpuhp_pin_lock, cpu);
+-#endif
+ 	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ 	int err;
+ 
+@@ -976,17 +928,38 @@ static int takedown_cpu(unsigned int cpu)
+ 	 */
+ 	irq_lock_sparse();
+ 
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	__write_rt_lock(cpuhp_pin);
++#ifdef CONFIG_PREEMPT_RT_BASE
++	WARN_ON_ONCE(takedown_cpu_task);
++	takedown_cpu_task = current;
++
++again:
++	/*
++	 * If a task pins this CPU after we pass this check, take_cpu_down
++	 * will return -EAGAIN.
++	 */
++	for (;;) {
++		int nr_pinned;
++
++		set_current_state(TASK_UNINTERRUPTIBLE);
++		nr_pinned = cpu_nr_pinned(cpu);
++		if (nr_pinned == 0)
++			break;
++		schedule();
++	}
++	set_current_state(TASK_RUNNING);
+ #endif
+ 
+ 	/*
+ 	 * So now all preempt/rcu users must observe !cpu_active().
+ 	 */
+ 	err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
++#ifdef CONFIG_PREEMPT_RT_BASE
++	if (err == -EAGAIN)
++		goto again;
++#endif
+ 	if (err) {
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-		__write_rt_unlock(cpuhp_pin);
++#ifdef CONFIG_PREEMPT_RT_BASE
++		takedown_cpu_task = NULL;
+ #endif
+ 		/* CPU refused to die */
+ 		irq_unlock_sparse();
+@@ -1006,8 +979,8 @@ static int takedown_cpu(unsigned int cpu)
+ 	wait_for_ap_thread(st, false);
+ 	BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
+ 
+-#ifdef CONFIG_PREEMPT_RT_FULL
+-	__write_rt_unlock(cpuhp_pin);
++#ifdef CONFIG_PREEMPT_RT_BASE
++	takedown_cpu_task = NULL;
+ #endif
+ 	/* Interrupts are moved away from the dying cpu, reenable alloc/free */
+ 	irq_unlock_sparse();
+diff --git a/kernel/sched/core.c b/kernel/sched/core.c
+index 7eb3037c0b35..de6514e13e0c 100644
+--- a/kernel/sched/core.c
++++ b/kernel/sched/core.c
+@@ -1065,7 +1065,8 @@ static int migration_cpu_stop(void *data)
+ void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
+ {
+ 	cpumask_copy(&p->cpus_mask, new_mask);
+-	p->nr_cpus_allowed = cpumask_weight(new_mask);
++	if (p->cpus_ptr == &p->cpus_mask)
++		p->nr_cpus_allowed = cpumask_weight(new_mask);
+ }
+ 
+ #if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+@@ -1076,8 +1077,7 @@ int __migrate_disabled(struct task_struct *p)
+ EXPORT_SYMBOL_GPL(__migrate_disabled);
+ #endif
+ 
+-static void __do_set_cpus_allowed_tail(struct task_struct *p,
+-				       const struct cpumask *new_mask)
++void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+ {
+ 	struct rq *rq = task_rq(p);
+ 	bool queued, running;
+@@ -1106,20 +1106,6 @@ static void __do_set_cpus_allowed_tail(struct task_struct *p,
+ 		set_curr_task(rq, p);
+ }
+ 
+-void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+-{
+-#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+-	if (__migrate_disabled(p)) {
+-		lockdep_assert_held(&p->pi_lock);
+-
+-		cpumask_copy(&p->cpus_mask, new_mask);
+-		p->migrate_disable_update = 1;
+-		return;
+-	}
+-#endif
+-	__do_set_cpus_allowed_tail(p, new_mask);
+-}
+-
+ /*
+  * Change a given task's CPU affinity. Migrate the thread to a
+  * proper CPU and schedule it away if the CPU it's executing on
+@@ -1179,7 +1165,8 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
+ 	}
+ 
+ 	/* Can the task run on the task's current CPU? If so, we're done */
+-	if (cpumask_test_cpu(task_cpu(p), new_mask) || __migrate_disabled(p))
++	if (cpumask_test_cpu(task_cpu(p), new_mask) ||
++	    p->cpus_ptr != &p->cpus_mask)
+ 		goto out;
+ 
+ 	if (task_running(rq, p) || p->state == TASK_WAKING) {
+@@ -3459,6 +3446,8 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+ 	BUG();
+ }
+ 
++static void migrate_disabled_sched(struct task_struct *p);
++
+ /*
+  * __schedule() is the main scheduler function.
+  *
+@@ -3529,6 +3518,9 @@ static void __sched notrace __schedule(bool preempt)
+ 	rq_lock(rq, &rf);
+ 	smp_mb__after_spinlock();
+ 
++	if (__migrate_disabled(prev))
++		migrate_disabled_sched(prev);
++
+ 	/* Promote REQ to ACT */
+ 	rq->clock_update_flags <<= 1;
+ 	update_rq_clock(rq);
+@@ -5777,6 +5769,8 @@ static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf)
+ 		BUG_ON(!next);
+ 		put_prev_task(rq, next);
+ 
++		WARN_ON_ONCE(__migrate_disabled(next));
++
+ 		/*
+ 		 * Rules for changing task_struct::cpus_mask are holding
+ 		 * both pi_lock and rq->lock, such that holding either
+@@ -7241,14 +7235,9 @@ update_nr_migratory(struct task_struct *p, long delta)
+ static inline void
+ migrate_disable_update_cpus_allowed(struct task_struct *p)
+ {
+-	struct rq *rq;
+-	struct rq_flags rf;
+-
+-	rq = task_rq_lock(p, &rf);
+ 	p->cpus_ptr = cpumask_of(smp_processor_id());
+ 	update_nr_migratory(p, -1);
+ 	p->nr_cpus_allowed = 1;
+-	task_rq_unlock(rq, p, &rf);
+ }
+ 
+ static inline void
+@@ -7266,54 +7255,35 @@ migrate_enable_update_cpus_allowed(struct task_struct *p)
+ 
+ void migrate_disable(void)
+ {
+-	struct task_struct *p = current;
++	preempt_disable();
+ 
+-	if (in_atomic() || irqs_disabled()) {
++	if (++current->migrate_disable == 1) {
++		this_rq()->nr_pinned++;
++		preempt_lazy_disable();
+ #ifdef CONFIG_SCHED_DEBUG
+-		p->migrate_disable_atomic++;
++		WARN_ON_ONCE(current->pinned_on_cpu >= 0);
++		current->pinned_on_cpu = smp_processor_id();
+ #endif
+-		return;
+-	}
+-#ifdef CONFIG_SCHED_DEBUG
+-	if (unlikely(p->migrate_disable_atomic)) {
+-		tracing_off();
+-		WARN_ON_ONCE(1);
+ 	}
+-#endif
+ 
+-	if (p->migrate_disable) {
+-		p->migrate_disable++;
+-		return;
+-	}
++	preempt_enable();
++}
++EXPORT_SYMBOL(migrate_disable);
+ 
+-	preempt_disable();
+-	preempt_lazy_disable();
+-	pin_current_cpu();
++static void migrate_disabled_sched(struct task_struct *p)
++{
++	if (p->migrate_disable_scheduled)
++		return;
+ 
+ 	migrate_disable_update_cpus_allowed(p);
+-	p->migrate_disable = 1;
+-
+-	preempt_enable();
++	p->migrate_disable_scheduled = 1;
+ }
+-EXPORT_SYMBOL(migrate_disable);
+ 
+ void migrate_enable(void)
+ {
+ 	struct task_struct *p = current;
+-
+-	if (in_atomic() || irqs_disabled()) {
+-#ifdef CONFIG_SCHED_DEBUG
+-		p->migrate_disable_atomic--;
+-#endif
+-		return;
+-	}
+-
+-#ifdef CONFIG_SCHED_DEBUG
+-	if (unlikely(p->migrate_disable_atomic)) {
+-		tracing_off();
+-		WARN_ON_ONCE(1);
+-	}
+-#endif
++	struct rq *rq = this_rq();
++	int cpu = task_cpu(p);
+ 
+ 	WARN_ON_ONCE(p->migrate_disable <= 0);
+ 	if (p->migrate_disable > 1) {
+@@ -7323,67 +7293,69 @@ void migrate_enable(void)
+ 
+ 	preempt_disable();
+ 
++#ifdef CONFIG_SCHED_DEBUG
++	WARN_ON_ONCE(current->pinned_on_cpu != cpu);
++	current->pinned_on_cpu = -1;
++#endif
++
++	WARN_ON_ONCE(rq->nr_pinned < 1);
++
+ 	p->migrate_disable = 0;
++	rq->nr_pinned--;
++	if (rq->nr_pinned == 0 && unlikely(!cpu_active(cpu)) &&
++	    takedown_cpu_task)
++		wake_up_process(takedown_cpu_task);
++
++	if (!p->migrate_disable_scheduled)
++		goto out;
++
++	p->migrate_disable_scheduled = 0;
++
+ 	migrate_enable_update_cpus_allowed(p);
+ 
+-	if (p->migrate_disable_update) {
+-		struct rq *rq;
++	WARN_ON(smp_processor_id() != cpu);
++	if (!is_cpu_allowed(p, cpu)) {
++		struct migration_arg arg = { p };
+ 		struct rq_flags rf;
+-		int cpu = task_cpu(p);
+ 
+ 		rq = task_rq_lock(p, &rf);
+ 		update_rq_clock(rq);
+-
+-		__do_set_cpus_allowed_tail(p, &p->cpus_mask);
++		arg.dest_cpu = select_fallback_rq(cpu, p);
+ 		task_rq_unlock(rq, p, &rf);
+ 
+-		p->migrate_disable_update = 0;
+-
+-		WARN_ON(smp_processor_id() != cpu);
+-		if (!cpumask_test_cpu(cpu, &p->cpus_mask)) {
+-			struct migration_arg arg = { p };
+-			struct rq_flags rf;
++		preempt_lazy_enable();
++		preempt_enable();
+ 
+-			rq = task_rq_lock(p, &rf);
+-			update_rq_clock(rq);
+-			arg.dest_cpu = select_fallback_rq(cpu, p);
+-			task_rq_unlock(rq, p, &rf);
+-
+-			unpin_current_cpu();
+-			preempt_lazy_enable();
+-			preempt_enable();
+-
+-			sleeping_lock_inc();
+-			stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
+-			sleeping_lock_dec();
+-			tlb_migrate_finish(p->mm);
++		sleeping_lock_inc();
++		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
++		sleeping_lock_dec();
++		tlb_migrate_finish(p->mm);
+ 
+-			return;
+-		}
++		return;
+ 	}
+-	unpin_current_cpu();
++
++out:
+ 	preempt_lazy_enable();
+ 	preempt_enable();
+ }
+ EXPORT_SYMBOL(migrate_enable);
+ 
+-#elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
+-void migrate_disable(void)
++int cpu_nr_pinned(int cpu)
+ {
+-#ifdef CONFIG_SCHED_DEBUG
+-	struct task_struct *p = current;
++	struct rq *rq = cpu_rq(cpu);
+ 
+-	if (in_atomic() || irqs_disabled()) {
+-		p->migrate_disable_atomic++;
+-		return;
+-	}
++	return rq->nr_pinned;
++}
+ 
+-	if (unlikely(p->migrate_disable_atomic)) {
+-		tracing_off();
+-		WARN_ON_ONCE(1);
+-	}
++#elif !defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT_BASE)
++static void migrate_disabled_sched(struct task_struct *p)
++{
++}
+ 
+-	p->migrate_disable++;
++void migrate_disable(void)
++{
++#ifdef CONFIG_SCHED_DEBUG
++	current->migrate_disable++;
+ #endif
+ 	barrier();
+ }
+@@ -7394,20 +7366,14 @@ void migrate_enable(void)
+ #ifdef CONFIG_SCHED_DEBUG
+ 	struct task_struct *p = current;
+ 
+-	if (in_atomic() || irqs_disabled()) {
+-		p->migrate_disable_atomic--;
+-		return;
+-	}
+-
+-	if (unlikely(p->migrate_disable_atomic)) {
+-		tracing_off();
+-		WARN_ON_ONCE(1);
+-	}
+-
+ 	WARN_ON_ONCE(p->migrate_disable <= 0);
+ 	p->migrate_disable--;
+ #endif
+ 	barrier();
+ }
+ EXPORT_SYMBOL(migrate_enable);
++#else
++static void migrate_disabled_sched(struct task_struct *p)
++{
++}
+ #endif
+diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
+index 87a05bb90124..45b3f135d205 100644
+--- a/kernel/sched/sched.h
++++ b/kernel/sched/sched.h
+@@ -915,6 +915,10 @@ struct rq {
+ 	/* Must be inspected within a rcu lock section */
+ 	struct cpuidle_state	*idle_state;
+ #endif
++
++#if defined(CONFIG_PREEMPT_RT_BASE) && defined(CONFIG_SMP)
++	int			nr_pinned;
++#endif
+ };
+ 
+ static inline int cpu_of(struct rq *rq)
+diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
+index b8a8a8db2d75..0c80992aa337 100644
+--- a/lib/smp_processor_id.c
++++ b/lib/smp_processor_id.c
+@@ -22,6 +22,9 @@ notrace static unsigned int check_preemption_disabled(const char *what1,
+ 	 * Kernel threads bound to a single CPU can safely use
+ 	 * smp_processor_id():
+ 	 */
++	if (current->migrate_disable)
++		goto out;
++
+ 	if (current->nr_cpus_allowed == 1)
+ 		goto out;
+ 
+-- 
+2.36.1
+