diff --git a/MAINTAINERS b/MAINTAINERS
index d8ebab595b2a..ee7e011f0b5e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14746,7 +14746,7 @@ F:	include/uapi/linux/nitro_enclaves.h
 F:	samples/nitro_enclaves/
 
 NOHZ, DYNTICKS SUPPORT
-M:	Frederic Weisbecker <fweisbec@gmail.com>
+M:	Frederic Weisbecker <frederic@kernel.org>
 M:	Thomas Gleixner <tglx@linutronix.de>
 M:	Ingo Molnar <mingo@kernel.org>
 L:	linux-kernel@vger.kernel.org
diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index a7ec06ce3785..515ca33b854c 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 hostprogs := vdsomunge
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index beaf9586338f..fe7a53c6781f 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -6,9 +6,7 @@
 # Heavily based on the vDSO Makefiles for other archs.
 #
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 obj-vdso := vgettimeofday.o note.o sigreturn.o
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index f59bd1a4ead6..d014162c5c71 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -3,9 +3,6 @@
 # Makefile for vdso32
 #
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32
 include $(srctree)/lib/vdso/Makefile
 
 # Same as cc-*option, but using CC_COMPAT instead of CC
diff --git a/arch/csky/kernel/vdso/Makefile b/arch/csky/kernel/vdso/Makefile
index 0b6909f10667..299e4e41ebc5 100644
--- a/arch/csky/kernel/vdso/Makefile
+++ b/arch/csky/kernel/vdso/Makefile
@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_CKCORE_ADDR32|R_CKCORE_JUMP_SLOT
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 # Symbols present in the vdso
diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
index d89e2ac75f7b..461240ab4436 100644
--- a/arch/loongarch/vdso/Makefile
+++ b/arch/loongarch/vdso/Makefile
@@ -1,9 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 # Objects to go into the VDSO.
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_LARCH_32|R_LARCH_64|R_LARCH_MARK_LA|R_LARCH_JUMP_SLOT
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 obj-vdso-y := elf.o vgetcpu.o vgettimeofday.o sigreturn.o
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index 18af9474ed0e..eb56581f6d73 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -4,9 +4,7 @@
 # Sanitizer runtimes are unavailable and cannot be linked here.
  KCSAN_SANITIZE			:= n
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_MIPS_JUMP_SLOT|R_MIPS_GLOB_DAT
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 obj-vdso-y := elf.o vgettimeofday.o sigreturn.o
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 66f723f53be2..4c3f34485f08 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -2,7 +2,7 @@
 
 # List of files in the vdso, has to be asm only for now
 
-ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN|R_PPC_REL24
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o
diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index 06e6b27f3bcc..a04b3bc35ca2 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -1,9 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 # Copied from arch/tile/kernel/vdso/Makefile
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_RISCV_32|R_RISCV_64|R_RISCV_JUMP_SLOT
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 # Symbols present in the vdso
 vdso-syms  = rt_sigreturn
diff --git a/arch/s390/kernel/vdso32/Makefile b/arch/s390/kernel/vdso32/Makefile
index 245bddfe9bc0..bafd3147eb4e 100644
--- a/arch/s390/kernel/vdso32/Makefile
+++ b/arch/s390/kernel/vdso32/Makefile
@@ -2,9 +2,8 @@
 # List of files in the vdso
 
 KCOV_INSTRUMENT := n
-ARCH_REL_TYPE_ABS := R_390_COPY|R_390_GLOB_DAT|R_390_JMP_SLOT|R_390_RELATIVE
-ARCH_REL_TYPE_ABS += R_390_GOT|R_390_PLT
 
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 obj-vdso32 = vdso_user_wrapper-32.o note-32.o
 
diff --git a/arch/s390/kernel/vdso64/Makefile b/arch/s390/kernel/vdso64/Makefile
index 34f9542636e9..a766d286e15f 100644
--- a/arch/s390/kernel/vdso64/Makefile
+++ b/arch/s390/kernel/vdso64/Makefile
@@ -2,9 +2,8 @@
 # List of files in the vdso
 
 KCOV_INSTRUMENT := n
-ARCH_REL_TYPE_ABS := R_390_COPY|R_390_GLOB_DAT|R_390_JMP_SLOT|R_390_RELATIVE
-ARCH_REL_TYPE_ABS += R_390_GOT|R_390_PLT
 
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 obj-vdso64 = vdso_user_wrapper.o note.o
 obj-cvdso64 = vdso64_generic.o getcpu.o
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 1506a22a4fb6..6a1821bd7d5e 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -3,10 +3,7 @@
 # Building vDSO images for x86.
 #
 
-# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
-# the inclusion of generic Makefile.
-ARCH_REL_TYPE_ABS := R_X86_64_JUMP_SLOT|R_X86_64_GLOB_DAT|R_X86_64_RELATIVE|
-ARCH_REL_TYPE_ABS += R_386_GLOB_DAT|R_386_JMP_SLOT|R_386_RELATIVE
+# Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
 # Sanitizer runtimes are unavailable and cannot be linked here.
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 2c6e99ca48af..d607f51404fc 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -4,6 +4,7 @@
 
 #include <linux/spinlock.h>
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/alarmtimer.h>
 #include <linux/timerqueue.h>
 
@@ -62,16 +63,18 @@ static inline int clockid_to_fd(const clockid_t clk)
  * cpu_timer - Posix CPU timer representation for k_itimer
  * @node:	timerqueue node to queue in the task/sig
  * @head:	timerqueue head on which this timer is queued
- * @task:	Pointer to target task
+ * @pid:	Pointer to target task PID
  * @elist:	List head for the expiry list
  * @firing:	Timer is currently firing
+ * @handling:	Pointer to the task which handles expiry
  */
 struct cpu_timer {
-	struct timerqueue_node	node;
-	struct timerqueue_head	*head;
-	struct pid		*pid;
-	struct list_head	elist;
-	int			firing;
+	struct timerqueue_node		node;
+	struct timerqueue_head		*head;
+	struct pid			*pid;
+	struct list_head		elist;
+	int				firing;
+	struct task_struct __rcu	*handling;
 };
 
 static inline bool cpu_timer_enqueue(struct timerqueue_head *head,
@@ -135,10 +138,12 @@ struct posix_cputimers {
 /**
  * posix_cputimers_work - Container for task work based posix CPU timer expiry
  * @work:	The task work to be scheduled
+ * @mutex:	Mutex held around expiry in context of this task work
  * @scheduled:  @work has been scheduled already, no further processing
  */
 struct posix_cputimers_work {
 	struct callback_head	work;
+	struct mutex		mutex;
 	unsigned int		scheduled;
 };
 
diff --git a/kernel/signal.c b/kernel/signal.c
index 8cb28f1df294..8f6330f0e9ca 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1003,8 +1003,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
 	/*
 	 * Now find a thread we can wake up to take the signal off the queue.
 	 *
-	 * If the main thread wants the signal, it gets first crack.
-	 * Probably the least surprising to the average bear.
+	 * Try the suggested task first (may or may not be the main thread).
 	 */
 	if (wants_signal(sig, p))
 		t = p;
@@ -1970,8 +1969,24 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
 
 	ret = -1;
 	rcu_read_lock();
+
+	/*
+	 * This function is used by POSIX timers to deliver a timer signal.
+	 * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
+	 * set), the signal must be delivered to the specific thread (queues
+	 * into t->pending).
+	 *
+	 * Where type is not PIDTYPE_PID, signals must be delivered to the
+	 * process. In this case, prefer to deliver to current if it is in
+	 * the same thread group as the target process, which avoids
+	 * unnecessarily waking up a potentially idle task.
+	 */
 	t = pid_task(pid, type);
-	if (!t || !likely(lock_task_sighand(t, &flags)))
+	if (!t)
+		goto ret;
+	if (type != PIDTYPE_PID && same_thread_group(t, current))
+		t = current;
+	if (!likely(lock_task_sighand(t, &flags)))
 		goto ret;
 
 	ret = 1; /* the signal is ignored */
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 2f5e9b34022c..e9c6f9d0e42c 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -846,6 +846,8 @@ static u64 collect_timerqueue(struct timerqueue_head *head,
 			return expires;
 
 		ctmr->firing = 1;
+		/* See posix_cpu_timer_wait_running() */
+		rcu_assign_pointer(ctmr->handling, current);
 		cpu_timer_dequeue(ctmr);
 		list_add_tail(&ctmr->elist, firing);
 	}
@@ -1161,7 +1163,49 @@ static void handle_posix_cpu_timers(struct task_struct *tsk);
 #ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
 static void posix_cpu_timers_work(struct callback_head *work)
 {
+	struct posix_cputimers_work *cw = container_of(work, typeof(*cw), work);
+
+	mutex_lock(&cw->mutex);
 	handle_posix_cpu_timers(current);
+	mutex_unlock(&cw->mutex);
+}
+
+/*
+ * Invoked from the posix-timer core when a cancel operation failed because
+ * the timer is marked firing. The caller holds rcu_read_lock(), which
+ * protects the timer and the task which is expiring it from being freed.
+ */
+static void posix_cpu_timer_wait_running(struct k_itimer *timr)
+{
+	struct task_struct *tsk = rcu_dereference(timr->it.cpu.handling);
+
+	/* Has the handling task completed expiry already? */
+	if (!tsk)
+		return;
+
+	/* Ensure that the task cannot go away */
+	get_task_struct(tsk);
+	/* Now drop the RCU protection so the mutex can be locked */
+	rcu_read_unlock();
+	/* Wait on the expiry mutex */
+	mutex_lock(&tsk->posix_cputimers_work.mutex);
+	/* Release it immediately again. */
+	mutex_unlock(&tsk->posix_cputimers_work.mutex);
+	/* Drop the task reference. */
+	put_task_struct(tsk);
+	/* Relock RCU so the callsite is balanced */
+	rcu_read_lock();
+}
+
+static void posix_cpu_timer_wait_running_nsleep(struct k_itimer *timr)
+{
+	/* Ensure that timr->it.cpu.handling task cannot go away */
+	rcu_read_lock();
+	spin_unlock_irq(&timr->it_lock);
+	posix_cpu_timer_wait_running(timr);
+	rcu_read_unlock();
+	/* @timr is on stack and is valid */
+	spin_lock_irq(&timr->it_lock);
 }
 
 /*
@@ -1177,6 +1221,7 @@ void clear_posix_cputimers_work(struct task_struct *p)
 	       sizeof(p->posix_cputimers_work.work));
 	init_task_work(&p->posix_cputimers_work.work,
 		       posix_cpu_timers_work);
+	mutex_init(&p->posix_cputimers_work.mutex);
 	p->posix_cputimers_work.scheduled = false;
 }
 
@@ -1255,6 +1300,18 @@ static inline void __run_posix_cpu_timers(struct task_struct *tsk)
 	lockdep_posixtimer_exit();
 }
 
+static void posix_cpu_timer_wait_running(struct k_itimer *timr)
+{
+	cpu_relax();
+}
+
+static void posix_cpu_timer_wait_running_nsleep(struct k_itimer *timr)
+{
+	spin_unlock_irq(&timr->it_lock);
+	cpu_relax();
+	spin_lock_irq(&timr->it_lock);
+}
+
 static inline bool posix_cpu_timers_work_scheduled(struct task_struct *tsk)
 {
 	return false;
@@ -1363,6 +1420,8 @@ static void handle_posix_cpu_timers(struct task_struct *tsk)
 		 */
 		if (likely(cpu_firing >= 0))
 			cpu_timer_fire(timer);
+		/* See posix_cpu_timer_wait_running() */
+		rcu_assign_pointer(timer->it.cpu.handling, NULL);
 		spin_unlock(&timer->it_lock);
 	}
 }
@@ -1497,23 +1556,16 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
 		expires = cpu_timer_getexpires(&timer.it.cpu);
 		error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
 		if (!error) {
-			/*
-			 * Timer is now unarmed, deletion can not fail.
-			 */
+			/* Timer is now unarmed, deletion can not fail. */
 			posix_cpu_timer_del(&timer);
+		} else {
+			while (error == TIMER_RETRY) {
+				posix_cpu_timer_wait_running_nsleep(&timer);
+				error = posix_cpu_timer_del(&timer);
+			}
 		}
-		spin_unlock_irq(&timer.it_lock);
 
-		while (error == TIMER_RETRY) {
-			/*
-			 * We need to handle case when timer was or is in the
-			 * middle of firing. In other cases we already freed
-			 * resources.
-			 */
-			spin_lock_irq(&timer.it_lock);
-			error = posix_cpu_timer_del(&timer);
-			spin_unlock_irq(&timer.it_lock);
-		}
+		spin_unlock_irq(&timer.it_lock);
 
 		if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
 			/*
@@ -1623,6 +1675,7 @@ const struct k_clock clock_posix_cpu = {
 	.timer_del		= posix_cpu_timer_del,
 	.timer_get		= posix_cpu_timer_get,
 	.timer_rearm		= posix_cpu_timer_rearm,
+	.timer_wait_running	= posix_cpu_timer_wait_running,
 };
 
 const struct k_clock clock_process = {
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 0c8a87a11b39..808a247205a9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -846,6 +846,10 @@ static struct k_itimer *timer_wait_running(struct k_itimer *timer,
 	rcu_read_lock();
 	unlock_timer(timer, *flags);
 
+	/*
+	 * kc->timer_wait_running() might drop RCU lock. So @timer
+	 * cannot be touched anymore after the function returns!
+	 */
 	if (!WARN_ON_ONCE(!kc->timer_wait_running))
 		kc->timer_wait_running(timer);
 
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 46789356f856..65b8658da829 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -218,9 +218,19 @@ static void tick_setup_device(struct tick_device *td,
 		 * this cpu:
 		 */
 		if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
+			ktime_t next_p;
+			u32 rem;
+
 			tick_do_timer_cpu = cpu;
 
-			tick_next_period = ktime_get();
+			next_p = ktime_get();
+			div_u64_rem(next_p, TICK_NSEC, &rem);
+			if (rem) {
+				next_p -= rem;
+				next_p += TICK_NSEC;
+			}
+
+			tick_next_period = next_p;
 #ifdef CONFIG_NO_HZ_FULL
 			/*
 			 * The boot CPU may be nohz_full, in which case set
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index b0e3c9205946..3b53b894ca98 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -637,43 +637,67 @@ static void tick_nohz_update_jiffies(ktime_t now)
 	touch_softlockup_watchdog_sched();
 }
 
-/*
- * Updates the per-CPU time idle statistics counters
- */
-static void
-update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time)
+static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
 {
 	ktime_t delta;
 
-	if (ts->idle_active) {
-		delta = ktime_sub(now, ts->idle_entrytime);
-		if (nr_iowait_cpu(cpu) > 0)
-			ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
-		else
-			ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
-		ts->idle_entrytime = now;
-	}
+	if (WARN_ON_ONCE(!ts->idle_active))
+		return;
 
-	if (last_update_time)
-		*last_update_time = ktime_to_us(now);
+	delta = ktime_sub(now, ts->idle_entrytime);
 
-}
+	write_seqcount_begin(&ts->idle_sleeptime_seq);
+	if (nr_iowait_cpu(smp_processor_id()) > 0)
+		ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
+	else
+		ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
 
-static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
-{
-	update_ts_time_stats(smp_processor_id(), ts, now, NULL);
+	ts->idle_entrytime = now;
 	ts->idle_active = 0;
+	write_seqcount_end(&ts->idle_sleeptime_seq);
 
 	sched_clock_idle_wakeup_event();
 }
 
 static void tick_nohz_start_idle(struct tick_sched *ts)
 {
+	write_seqcount_begin(&ts->idle_sleeptime_seq);
 	ts->idle_entrytime = ktime_get();
 	ts->idle_active = 1;
+	write_seqcount_end(&ts->idle_sleeptime_seq);
+
 	sched_clock_idle_sleep_event();
 }
 
+static u64 get_cpu_sleep_time_us(struct tick_sched *ts, ktime_t *sleeptime,
+				 bool compute_delta, u64 *last_update_time)
+{
+	ktime_t now, idle;
+	unsigned int seq;
+
+	if (!tick_nohz_active)
+		return -1;
+
+	now = ktime_get();
+	if (last_update_time)
+		*last_update_time = ktime_to_us(now);
+
+	do {
+		seq = read_seqcount_begin(&ts->idle_sleeptime_seq);
+
+		if (ts->idle_active && compute_delta) {
+			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
+
+			idle = ktime_add(*sleeptime, delta);
+		} else {
+			idle = *sleeptime;
+		}
+	} while (read_seqcount_retry(&ts->idle_sleeptime_seq, seq));
+
+	return ktime_to_us(idle);
+
+}
+
 /**
  * get_cpu_idle_time_us - get the total idle time of a CPU
  * @cpu: CPU number to query
@@ -681,7 +705,10 @@ static void tick_nohz_start_idle(struct tick_sched *ts)
  * counters if NULL.
  *
  * Return the cumulative idle time (since boot) for a given
- * CPU, in microseconds.
+ * CPU, in microseconds. Note this is partially broken due to
+ * the counter of iowait tasks that can be remotely updated without
+ * any synchronization. Therefore it is possible to observe backward
+ * values within two consecutive reads.
  *
  * This time is measured via accounting rather than sampling,
  * and is as accurate as ktime_get() is.
@@ -691,27 +718,9 @@ static void tick_nohz_start_idle(struct tick_sched *ts)
 u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
-	ktime_t now, idle;
-
-	if (!tick_nohz_active)
-		return -1;
-
-	now = ktime_get();
-	if (last_update_time) {
-		update_ts_time_stats(cpu, ts, now, last_update_time);
-		idle = ts->idle_sleeptime;
-	} else {
-		if (ts->idle_active && !nr_iowait_cpu(cpu)) {
-			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
-
-			idle = ktime_add(ts->idle_sleeptime, delta);
-		} else {
-			idle = ts->idle_sleeptime;
-		}
-	}
-
-	return ktime_to_us(idle);
 
+	return get_cpu_sleep_time_us(ts, &ts->idle_sleeptime,
+				     !nr_iowait_cpu(cpu), last_update_time);
 }
 EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
 
@@ -722,7 +731,10 @@ EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
  * counters if NULL.
  *
  * Return the cumulative iowait time (since boot) for a given
- * CPU, in microseconds.
+ * CPU, in microseconds. Note this is partially broken due to
+ * the counter of iowait tasks that can be remotely updated without
+ * any synchronization. Therefore it is possible to observe backward
+ * values within two consecutive reads.
  *
  * This time is measured via accounting rather than sampling,
  * and is as accurate as ktime_get() is.
@@ -732,26 +744,9 @@ EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
 u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
-	ktime_t now, iowait;
 
-	if (!tick_nohz_active)
-		return -1;
-
-	now = ktime_get();
-	if (last_update_time) {
-		update_ts_time_stats(cpu, ts, now, last_update_time);
-		iowait = ts->iowait_sleeptime;
-	} else {
-		if (ts->idle_active && nr_iowait_cpu(cpu) > 0) {
-			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
-
-			iowait = ktime_add(ts->iowait_sleeptime, delta);
-		} else {
-			iowait = ts->iowait_sleeptime;
-		}
-	}
-
-	return ktime_to_us(iowait);
+	return get_cpu_sleep_time_us(ts, &ts->iowait_sleeptime,
+				     nr_iowait_cpu(cpu), last_update_time);
 }
 EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
 
@@ -1084,10 +1079,16 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 	return true;
 }
 
-static void __tick_nohz_idle_stop_tick(struct tick_sched *ts)
+/**
+ * tick_nohz_idle_stop_tick - stop the idle tick from the idle task
+ *
+ * When the next event is more than a tick into the future, stop the idle tick
+ */
+void tick_nohz_idle_stop_tick(void)
 {
-	ktime_t expires;
+	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
 	int cpu = smp_processor_id();
+	ktime_t expires;
 
 	/*
 	 * If tick_nohz_get_sleep_length() ran tick_nohz_next_event(), the
@@ -1119,16 +1120,6 @@ static void __tick_nohz_idle_stop_tick(struct tick_sched *ts)
 	}
 }
 
-/**
- * tick_nohz_idle_stop_tick - stop the idle tick from the idle task
- *
- * When the next event is more than a tick into the future, stop the idle tick
- */
-void tick_nohz_idle_stop_tick(void)
-{
-	__tick_nohz_idle_stop_tick(this_cpu_ptr(&tick_cpu_sched));
-}
-
 void tick_nohz_idle_retain_tick(void)
 {
 	tick_nohz_retain_tick(this_cpu_ptr(&tick_cpu_sched));
diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index 504649513399..5ed5a9d41d5a 100644
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -22,65 +22,82 @@ enum tick_nohz_mode {
 
 /**
  * struct tick_sched - sched tick emulation and no idle tick control/stats
- * @sched_timer:	hrtimer to schedule the periodic tick in high
- *			resolution mode
- * @check_clocks:	Notification mechanism about clocksource changes
- * @nohz_mode:		Mode - one state of tick_nohz_mode
+ *
  * @inidle:		Indicator that the CPU is in the tick idle mode
  * @tick_stopped:	Indicator that the idle tick has been stopped
  * @idle_active:	Indicator that the CPU is actively in the tick idle mode;
  *			it is reset during irq handling phases.
- * @do_timer_lst:	CPU was the last one doing do_timer before going idle
+ * @do_timer_last:	CPU was the last one doing do_timer before going idle
  * @got_idle_tick:	Tick timer function has run with @inidle set
+ * @stalled_jiffies:	Number of stalled jiffies detected across ticks
+ * @last_tick_jiffies:	Value of jiffies seen on last tick
+ * @sched_timer:	hrtimer to schedule the periodic tick in high
+ *			resolution mode
  * @last_tick:		Store the last tick expiry time when the tick
  *			timer is modified for nohz sleeps. This is necessary
  *			to resume the tick timer operation in the timeline
  *			when the CPU returns from nohz sleep.
  * @next_tick:		Next tick to be fired when in dynticks mode.
  * @idle_jiffies:	jiffies at the entry to idle for idle time accounting
+ * @idle_waketime:	Time when the idle was interrupted
+ * @idle_entrytime:	Time when the idle call was entered
+ * @nohz_mode:		Mode - one state of tick_nohz_mode
+ * @last_jiffies:	Base jiffies snapshot when next event was last computed
+ * @timer_expires_base:	Base time clock monotonic for @timer_expires
+ * @timer_expires:	Anticipated timer expiration time (in case sched tick is stopped)
+ * @next_timer:		Expiry time of next expiring timer for debugging purpose only
+ * @idle_expires:	Next tick in idle, for debugging purpose only
  * @idle_calls:		Total number of idle calls
  * @idle_sleeps:	Number of idle calls, where the sched tick was stopped
- * @idle_entrytime:	Time when the idle call was entered
- * @idle_waketime:	Time when the idle was interrupted
  * @idle_exittime:	Time when the idle state was left
  * @idle_sleeptime:	Sum of the time slept in idle with sched tick stopped
  * @iowait_sleeptime:	Sum of the time slept in idle with sched tick stopped, with IO outstanding
- * @timer_expires:	Anticipated timer expiration time (in case sched tick is stopped)
- * @timer_expires_base:	Base time clock monotonic for @timer_expires
- * @next_timer:		Expiry time of next expiring timer for debugging purpose only
  * @tick_dep_mask:	Tick dependency mask - is set, if someone needs the tick
- * @last_tick_jiffies:	Value of jiffies seen on last tick
- * @stalled_jiffies:	Number of stalled jiffies detected across ticks
+ * @check_clocks:	Notification mechanism about clocksource changes
  */
 struct tick_sched {
-	struct hrtimer			sched_timer;
-	unsigned long			check_clocks;
-	enum tick_nohz_mode		nohz_mode;
-
+	/* Common flags */
 	unsigned int			inidle		: 1;
 	unsigned int			tick_stopped	: 1;
 	unsigned int			idle_active	: 1;
 	unsigned int			do_timer_last	: 1;
 	unsigned int			got_idle_tick	: 1;
 
+	/* Tick handling: jiffies stall check */
+	unsigned int			stalled_jiffies;
+	unsigned long			last_tick_jiffies;
+
+	/* Tick handling */
+	struct hrtimer			sched_timer;
 	ktime_t				last_tick;
 	ktime_t				next_tick;
 	unsigned long			idle_jiffies;
-	unsigned long			idle_calls;
-	unsigned long			idle_sleeps;
-	ktime_t				idle_entrytime;
 	ktime_t				idle_waketime;
-	ktime_t				idle_exittime;
-	ktime_t				idle_sleeptime;
-	ktime_t				iowait_sleeptime;
+
+	/* Idle entry */
+	seqcount_t			idle_sleeptime_seq;
+	ktime_t				idle_entrytime;
+
+	/* Tick stop */
+	enum tick_nohz_mode		nohz_mode;
 	unsigned long			last_jiffies;
-	u64				timer_expires;
 	u64				timer_expires_base;
+	u64				timer_expires;
 	u64				next_timer;
 	ktime_t				idle_expires;
+	unsigned long			idle_calls;
+	unsigned long			idle_sleeps;
+
+	/* Idle exit */
+	ktime_t				idle_exittime;
+	ktime_t				idle_sleeptime;
+	ktime_t				iowait_sleeptime;
+
+	/* Full dynticks handling */
 	atomic_t			tick_dep_mask;
-	unsigned long			last_tick_jiffies;
-	unsigned int			stalled_jiffies;
+
+	/* Clocksource changes */
+	unsigned long			check_clocks;
 };
 
 extern struct tick_sched *tick_get_tick_sched(int cpu);
diff --git a/lib/vdso/Makefile b/lib/vdso/Makefile
index e814061d6aa0..9f031eafc465 100644
--- a/lib/vdso/Makefile
+++ b/lib/vdso/Makefile
@@ -5,18 +5,13 @@ GENERIC_VDSO_DIR := $(dir $(GENERIC_VDSO_MK_PATH))
 
 c-gettimeofday-$(CONFIG_GENERIC_GETTIMEOFDAY) := $(addprefix $(GENERIC_VDSO_DIR), gettimeofday.c)
 
-# This cmd checks that the vdso library does not contain absolute relocation
+# This cmd checks that the vdso library does not contain dynamic relocations.
 # It has to be called after the linking of the vdso library and requires it
 # as a parameter.
 #
-# $(ARCH_REL_TYPE_ABS) is defined in the arch specific makefile and corresponds
-# to the absolute relocation types printed by "objdump -R" and accepted by the
-# dynamic linker.
-ifndef ARCH_REL_TYPE_ABS
-$(error ARCH_REL_TYPE_ABS is not set)
-endif
-
+# As a workaround for some GNU ld ports which produce unneeded R_*_NONE
+# dynamic relocations, ignore R_*_NONE.
 quiet_cmd_vdso_check = VDSOCHK $@
-      cmd_vdso_check = if $(OBJDUMP) -R $@ | grep -E -h "$(ARCH_REL_TYPE_ABS)"; \
+      cmd_vdso_check = if $(READELF) -rW $@ | grep -v _NONE | grep -q " R_\w*_"; \
 		       then (echo >&2 "$@: dynamic relocations are not supported"; \
 			     rm -f $@; /bin/false); fi
diff --git a/tools/testing/selftests/proc/proc-uptime-001.c b/tools/testing/selftests/proc/proc-uptime-001.c
index 781f7a50fc3f..f335eec5067e 100644
--- a/tools/testing/selftests/proc/proc-uptime-001.c
+++ b/tools/testing/selftests/proc/proc-uptime-001.c
@@ -13,7 +13,9 @@
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
-// Test that values in /proc/uptime increment monotonically.
+// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
+// monotonically. We don't test idle time monotonicity due to broken iowait
+// task counting, cf: comment above get_cpu_idle_time_us()
 #undef NDEBUG
 #include <assert.h>
 #include <stdint.h>
@@ -25,20 +27,31 @@
 
 int main(void)
 {
-	uint64_t start, u0, u1, i0, i1;
+	uint64_t start, u0, u1, c0, c1;
 	int fd;
 
 	fd = open("/proc/uptime", O_RDONLY);
 	assert(fd >= 0);
 
-	proc_uptime(fd, &u0, &i0);
+	u0 = proc_uptime(fd);
 	start = u0;
+	c0 = clock_boottime();
+
 	do {
-		proc_uptime(fd, &u1, &i1);
+		u1 = proc_uptime(fd);
+		c1 = clock_boottime();
+
+		/* Is /proc/uptime monotonic ? */
 		assert(u1 >= u0);
-		assert(i1 >= i0);
+
+		/* Is CLOCK_BOOTTIME monotonic ? */
+		assert(c1 >= c0);
+
+		/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
+		assert(c0 >= u0);
+
 		u0 = u1;
-		i0 = i1;
+		c0 = c1;
 	} while (u1 - start < 100);
 
 	return 0;
diff --git a/tools/testing/selftests/proc/proc-uptime-002.c b/tools/testing/selftests/proc/proc-uptime-002.c
index 7d0aa22bdc12..ae453daa96c1 100644
--- a/tools/testing/selftests/proc/proc-uptime-002.c
+++ b/tools/testing/selftests/proc/proc-uptime-002.c
@@ -13,8 +13,10 @@
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
-// Test that values in /proc/uptime increment monotonically
-// while shifting across CPUs.
+// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
+// monotonically while shifting across CPUs. We don't test idle time
+// monotonicity due to broken iowait task counting, cf: comment above
+// get_cpu_idle_time_us()
 #undef NDEBUG
 #include <assert.h>
 #include <errno.h>
@@ -42,10 +44,10 @@ static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned lo
 
 int main(void)
 {
+	uint64_t u0, u1, c0, c1;
 	unsigned int len;
 	unsigned long *m;
 	unsigned int cpu;
-	uint64_t u0, u1, i0, i1;
 	int fd;
 
 	/* find out "nr_cpu_ids" */
@@ -60,7 +62,9 @@ int main(void)
 	fd = open("/proc/uptime", O_RDONLY);
 	assert(fd >= 0);
 
-	proc_uptime(fd, &u0, &i0);
+	u0 = proc_uptime(fd);
+	c0 = clock_boottime();
+
 	for (cpu = 0; cpu < len * 8; cpu++) {
 		memset(m, 0, len);
 		m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
@@ -68,11 +72,20 @@ int main(void)
 		/* CPU might not exist, ignore error */
 		sys_sched_setaffinity(0, len, m);
 
-		proc_uptime(fd, &u1, &i1);
+		u1 = proc_uptime(fd);
+		c1 = clock_boottime();
+
+		/* Is /proc/uptime monotonic ? */
 		assert(u1 >= u0);
-		assert(i1 >= i0);
+
+		/* Is CLOCK_BOOTTIME monotonic ? */
+		assert(c1 >= c0);
+
+		/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
+		assert(c0 >= u0);
+
 		u0 = u1;
-		i0 = i1;
+		c0 = c1;
 	}
 
 	return 0;
diff --git a/tools/testing/selftests/proc/proc-uptime.h b/tools/testing/selftests/proc/proc-uptime.h
index dc6a42b1d6b0..730cce4a3d73 100644
--- a/tools/testing/selftests/proc/proc-uptime.h
+++ b/tools/testing/selftests/proc/proc-uptime.h
@@ -19,10 +19,22 @@
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <time.h>
 
 #include "proc.h"
 
-static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
+static uint64_t clock_boottime(void)
+{
+	struct timespec ts;
+	int err;
+
+	err = clock_gettime(CLOCK_BOOTTIME, &ts);
+	assert(err >= 0);
+
+	return (ts.tv_sec * 100) + (ts.tv_nsec / 10000000);
+}
+
+static uint64_t proc_uptime(int fd)
 {
 	uint64_t val1, val2;
 	char buf[64], *p;
@@ -43,18 +55,6 @@ static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
 	assert(p[3] == ' ');
 
 	val2 = (p[1] - '0') * 10 + p[2] - '0';
-	*uptime = val1 * 100 + val2;
-
-	p += 4;
-
-	val1 = xstrtoull(p, &p);
-	assert(p[0] == '.');
-	assert('0' <= p[1] && p[1] <= '9');
-	assert('0' <= p[2] && p[2] <= '9');
-	assert(p[3] == '\n');
-
-	val2 = (p[1] - '0') * 10 + p[2] - '0';
-	*idle = val1 * 100 + val2;
 
-	assert(p + 4 == buf + rv);
+	return val1 * 100 + val2;
 }
diff --git a/tools/testing/selftests/timers/posix_timers.c b/tools/testing/selftests/timers/posix_timers.c
index 0ba500056e63..8a17c0e8d82b 100644
--- a/tools/testing/selftests/timers/posix_timers.c
+++ b/tools/testing/selftests/timers/posix_timers.c
@@ -188,6 +188,80 @@ static int check_timer_create(int which)
 	return 0;
 }
 
+int remain;
+__thread int got_signal;
+
+static void *distribution_thread(void *arg)
+{
+	while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
+	return NULL;
+}
+
+static void distribution_handler(int nr)
+{
+	if (!__atomic_exchange_n(&got_signal, 1, __ATOMIC_RELAXED))
+		__atomic_fetch_sub(&remain, 1, __ATOMIC_RELAXED);
+}
+
+/*
+ * Test that all running threads _eventually_ receive CLOCK_PROCESS_CPUTIME_ID
+ * timer signals. This primarily tests that the kernel does not favour any one.
+ */
+static int check_timer_distribution(void)
+{
+	int err, i;
+	timer_t id;
+	const int nthreads = 10;
+	pthread_t threads[nthreads];
+	struct itimerspec val = {
+		.it_value.tv_sec = 0,
+		.it_value.tv_nsec = 1000 * 1000,
+		.it_interval.tv_sec = 0,
+		.it_interval.tv_nsec = 1000 * 1000,
+	};
+
+	printf("Check timer_create() per process signal distribution... ");
+	fflush(stdout);
+
+	remain = nthreads + 1;  /* worker threads + this thread */
+	signal(SIGALRM, distribution_handler);
+	err = timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id);
+	if (err < 0) {
+		perror("Can't create timer\n");
+		return -1;
+	}
+	err = timer_settime(id, 0, &val, NULL);
+	if (err < 0) {
+		perror("Can't set timer\n");
+		return -1;
+	}
+
+	for (i = 0; i < nthreads; i++) {
+		if (pthread_create(&threads[i], NULL, distribution_thread, NULL)) {
+			perror("Can't create thread\n");
+			return -1;
+		}
+	}
+
+	/* Wait for all threads to receive the signal. */
+	while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
+
+	for (i = 0; i < nthreads; i++) {
+		if (pthread_join(threads[i], NULL)) {
+			perror("Can't join thread\n");
+			return -1;
+		}
+	}
+
+	if (timer_delete(id)) {
+		perror("Can't delete timer\n");
+		return -1;
+	}
+
+	printf("[OK]\n");
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	printf("Testing posix timers. False negative may happen on CPU execution \n");
@@ -217,5 +291,8 @@ int main(int argc, char **argv)
 	if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
 		return ksft_exit_fail();
 
+	if (check_timer_distribution() < 0)
+		return ksft_exit_fail();
+
 	return ksft_exit_pass();
 }
