diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 7fb482f0f25b062c073294ef72fd6936bf36c41c..3df0a95c9e134c78c1993bb64ee17c817e5970a8 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -65,7 +65,7 @@
  */
 static __always_inline void boot_init_stack_canary(void)
 {
-	u64 canary;
+	u64 canary = 0;
 	u64 tsc;
 
 #ifdef CONFIG_X86_64
@@ -76,8 +76,14 @@ static __always_inline void boot_init_stack_canary(void)
 	 * of randomness. The TSC only matters for very early init,
 	 * there it already has some randomness on most systems. Later
 	 * on during the bootup the random pool has true entropy too.
+	 * For preempt-rt we need to weaken the randomness a bit, as
+	 * we can't call into the random generator from atomic context
+	 * due to locking constraints. We just leave canary
+	 * uninitialized and use the TSC based randomness on top of it.
 	 */
+#ifndef CONFIG_PREEMPT_RT
 	get_random_bytes(&canary, sizeof(canary));
+#endif
 	tsc = rdtsc();
 	canary += tsc + (tsc << 32UL);
 	canary &= CANARY_MASK;
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
index 1603d24a648686a9e4b8c4101f1fb1ff9eae7afa..7d181ced374630ad6d59fecabfad035c6930e314 100644
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -58,4 +58,10 @@ static inline void irq_work_run(void) { }
 static inline void irq_work_single(void *arg) { }
 #endif
 
+#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_PREEMPT_RT)
+void irq_work_tick_soft(void);
+#else
+static inline void irq_work_tick_soft(void) { }
+#endif
+
 #endif /* _LINUX_IRQ_WORK_H */
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index eca83965b631ab11d21d5a7f726a0ba06faabc30..8183d30e1bb1c04d1e8e77fdab82496a911f6923 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -18,6 +18,7 @@
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/smp.h>
+#include <linux/interrupt.h>
 #include <asm/processor.h>
 
 
@@ -52,13 +53,19 @@ void __weak arch_irq_work_raise(void)
 /* Enqueue on current CPU, work must already be claimed and preempt disabled */
 static void __irq_work_queue_local(struct irq_work *work)
 {
+	struct llist_head *list;
+	bool lazy_work, realtime = IS_ENABLED(CONFIG_PREEMPT_RT);
+
+	lazy_work = atomic_read(&work->flags) & IRQ_WORK_LAZY;
+
 	/* If the work is "lazy", handle it from next tick if any */
-	if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
-		if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
-		    tick_nohz_tick_stopped())
-			arch_irq_work_raise();
-	} else {
-		if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
+	if (lazy_work || (realtime && !(atomic_read(&work->flags) & IRQ_WORK_HARD_IRQ)))
+		list = this_cpu_ptr(&lazy_list);
+	else
+		list = this_cpu_ptr(&raised_list);
+
+	if (llist_add(&work->llnode, list)) {
+		if (!lazy_work || tick_nohz_tick_stopped())
 			arch_irq_work_raise();
 	}
 }
@@ -102,7 +109,13 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
 	if (cpu != smp_processor_id()) {
 		/* Arch remote IPI send/receive backend aren't NMI safe */
 		WARN_ON_ONCE(in_nmi());
-		__smp_call_single_queue(cpu, &work->llnode);
+
+		if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(atomic_read(&work->flags) & IRQ_WORK_HARD_IRQ)) {
+			if (llist_add(&work->llnode, &per_cpu(lazy_list, cpu)))
+				arch_send_call_function_single_ipi(cpu);
+		} else {
+			__smp_call_single_queue(cpu, &work->llnode);
+		}
 	} else {
 		__irq_work_queue_local(work);
 	}
@@ -120,9 +133,8 @@ bool irq_work_needs_cpu(void)
 	raised = this_cpu_ptr(&raised_list);
 	lazy = this_cpu_ptr(&lazy_list);
 
-	if (llist_empty(raised) || arch_irq_work_has_interrupt())
-		if (llist_empty(lazy))
-			return false;
+	if (llist_empty(raised) && llist_empty(lazy))
+		return false;
 
 	/* All work should have been flushed before going offline */
 	WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
@@ -160,8 +172,12 @@ static void irq_work_run_list(struct llist_head *list)
 	struct irq_work *work, *tmp;
 	struct llist_node *llnode;
 
+#ifndef CONFIG_PREEMPT_RT
+	/*
+	 * nort: On RT IRQ-work may run in SOFTIRQ context.
+	 */
 	BUG_ON(!irqs_disabled());
-
+#endif
 	if (llist_empty(list))
 		return;
 
@@ -177,7 +193,16 @@ static void irq_work_run_list(struct llist_head *list)
 void irq_work_run(void)
 {
 	irq_work_run_list(this_cpu_ptr(&raised_list));
-	irq_work_run_list(this_cpu_ptr(&lazy_list));
+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		/*
+		 * NOTE: we raise softirq via IPI for safety,
+		 * and execute in irq_work_tick() to move the
+		 * overhead from hard to soft irq context.
+		 */
+		if (!llist_empty(this_cpu_ptr(&lazy_list)))
+			raise_softirq(TIMER_SOFTIRQ);
+	} else
+		irq_work_run_list(this_cpu_ptr(&lazy_list));
 }
 EXPORT_SYMBOL_GPL(irq_work_run);
 
@@ -187,8 +212,17 @@ void irq_work_tick(void)
 
 	if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
 		irq_work_run_list(raised);
+
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		irq_work_run_list(this_cpu_ptr(&lazy_list));
+}
+
+#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_PREEMPT_RT)
+void irq_work_tick_soft(void)
+{
 	irq_work_run_list(this_cpu_ptr(&lazy_list));
 }
+#endif
 
 /*
  * Synchronize against the irq_work @entry, ensures the entry is not
diff --git a/kernel/panic.c b/kernel/panic.c
index 1198b962402f318ea4a62181fe1390f26fcbb5e4..1df51aa0138bbb1f84506f025df77ea55dfec7f1 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -549,9 +549,11 @@ static u64 oops_id;
 
 static int init_oops_id(void)
 {
+#ifndef CONFIG_PREEMPT_RT
 	if (!oops_id)
 		get_random_bytes(&oops_id, sizeof(oops_id));
 	else
+#endif
 		oops_id++;
 
 	return 0;
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 94f1e6299aa19ba337ae73bea414b9612b706d35..1cb071dd908cff9531e041df8e838cd27d10c584 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -514,6 +514,7 @@ static int init_rootdomain(struct root_domain *rd)
 	rd->rto_cpu = -1;
 	raw_spin_lock_init(&rd->rto_lock);
 	init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
+	atomic_or(IRQ_WORK_HARD_IRQ, &rd->rto_push_work.flags);
 #endif
 
 	init_dl_bw(&rd->dl_bw);
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index a4fdc7cfb723bc4a2b195fc396f3019080ec6295..1cad0efd635c917e61c2b28fff147d60849b63fc 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1770,6 +1770,8 @@ static __latent_entropy void run_timer_softirq(struct softirq_action *h)
 {
 	struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
 
+	irq_work_tick_soft();
+
 	__run_timers(base);
 	if (IS_ENABLED(CONFIG_NO_HZ_COMMON))
 		__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));
diff --git a/net/core/dev.c b/net/core/dev.c
index 23a1534fd9911a3caaa16f1c4666a7bf4e45a553..016b1bf29ca5118dd064e6084a05088e1221663d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4824,7 +4824,7 @@ static int netif_rx_internal(struct sk_buff *skb)
 		struct rps_dev_flow voidflow, *rflow = &voidflow;
 		int cpu;
 
-		preempt_disable();
+		migrate_disable();
 		rcu_read_lock();
 
 		cpu = get_rps_cpu(skb->dev, skb, &rflow);
@@ -4834,14 +4834,14 @@ static int netif_rx_internal(struct sk_buff *skb)
 		ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
 
 		rcu_read_unlock();
-		preempt_enable();
+		migrate_enable();
 	} else
 #endif
 	{
 		unsigned int qtail;
 
-		ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
-		put_cpu();
+		ret = enqueue_to_backlog(skb, get_cpu_light(), &qtail);
+		put_cpu_light();
 	}
 	return ret;
 }