diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index a667078..fed2ab1 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1960,7 +1960,8 @@
 
 static int intel_alt_er(int idx, u64 config)
 {
-	int alt_idx;
+	int alt_idx = idx;
+
 	if (!(x86_pmu.flags & PMU_FL_HAS_RSP_1))
 		return idx;
 
@@ -2897,14 +2898,12 @@
 		return;
 
 	if (!(x86_pmu.flags & PMU_FL_NO_HT_SHARING)) {
-		void **onln = &cpuc->kfree_on_online[X86_PERF_KFREE_SHARED];
-
 		for_each_cpu(i, topology_sibling_cpumask(cpu)) {
 			struct intel_shared_regs *pc;
 
 			pc = per_cpu(cpu_hw_events, i).shared_regs;
 			if (pc && pc->core_id == core_id) {
-				*onln = cpuc->shared_regs;
+				cpuc->kfree_on_online[0] = cpuc->shared_regs;
 				cpuc->shared_regs = pc;
 				break;
 			}
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index f97f807..3bf41d4 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -995,6 +995,9 @@
 	case 87: /* Knights Landing */
 		ret = knl_uncore_pci_init();
 		break;
+	case 94: /* SkyLake */
+		ret = skl_uncore_pci_init();
+		break;
 	default:
 		return 0;
 	}
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.h b/arch/x86/kernel/cpu/perf_event_intel_uncore.h
index 07aa2d6..a7086b8 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.h
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.h
@@ -336,6 +336,7 @@
 int ivb_uncore_pci_init(void);
 int hsw_uncore_pci_init(void);
 int bdw_uncore_pci_init(void);
+int skl_uncore_pci_init(void);
 void snb_uncore_cpu_init(void);
 void nhm_uncore_cpu_init(void);
 int snb_pci2phy_map_init(int devid);
diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c b/arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c
index 0b93482..2bd030d 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore_snb.c
@@ -8,6 +8,7 @@
 #define PCI_DEVICE_ID_INTEL_HSW_IMC	0x0c00
 #define PCI_DEVICE_ID_INTEL_HSW_U_IMC	0x0a04
 #define PCI_DEVICE_ID_INTEL_BDW_IMC	0x1604
+#define PCI_DEVICE_ID_INTEL_SKL_IMC	0x191f
 
 /* SNB event control */
 #define SNB_UNC_CTL_EV_SEL_MASK			0x000000ff
@@ -524,6 +525,14 @@
 	{ /* end: all zeroes */ },
 };
 
+static const struct pci_device_id skl_uncore_pci_ids[] = {
+	{ /* IMC */
+		PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_SKL_IMC),
+		.driver_data = UNCORE_PCI_DEV_DATA(SNB_PCI_UNCORE_IMC, 0),
+	},
+	{ /* end: all zeroes */ },
+};
+
 static struct pci_driver snb_uncore_pci_driver = {
 	.name		= "snb_uncore",
 	.id_table	= snb_uncore_pci_ids,
@@ -544,6 +553,11 @@
 	.id_table	= bdw_uncore_pci_ids,
 };
 
+static struct pci_driver skl_uncore_pci_driver = {
+	.name		= "skl_uncore",
+	.id_table	= skl_uncore_pci_ids,
+};
+
 struct imc_uncore_pci_dev {
 	__u32 pci_id;
 	struct pci_driver *driver;
@@ -558,6 +572,7 @@
 	IMC_DEV(HSW_IMC, &hsw_uncore_pci_driver),    /* 4th Gen Core Processor */
 	IMC_DEV(HSW_U_IMC, &hsw_uncore_pci_driver),  /* 4th Gen Core ULT Mobile Processor */
 	IMC_DEV(BDW_IMC, &bdw_uncore_pci_driver),    /* 5th Gen Core U */
+	IMC_DEV(SKL_IMC, &skl_uncore_pci_driver),    /* 6th Gen Core */
 	{  /* end marker */ }
 };
 
@@ -610,6 +625,11 @@
 	return imc_uncore_pci_init();
 }
 
+int skl_uncore_pci_init(void)
+{
+	return imc_uncore_pci_init();
+}
+
 /* end of Sandy Bridge uncore support */
 
 /* Nehalem uncore support */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f9828a4..b35a61a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -634,9 +634,6 @@
 	int				nr_cgroups;	 /* cgroup evts */
 	void				*task_ctx_data; /* pmu specific data */
 	struct rcu_head			rcu_head;
-
-	struct delayed_work		orphans_remove;
-	bool				orphans_remove_sched;
 };
 
 /*
@@ -729,7 +726,7 @@
 extern void perf_event_exit_task(struct task_struct *child);
 extern void perf_event_free_task(struct task_struct *task);
 extern void perf_event_delayed_put(struct task_struct *task);
-extern struct perf_event *perf_event_get(unsigned int fd);
+extern struct file *perf_event_get(unsigned int fd);
 extern const struct perf_event_attr *perf_event_attrs(struct perf_event *event);
 extern void perf_event_print_debug(void);
 extern void perf_pmu_disable(struct pmu *pmu);
@@ -1044,7 +1041,7 @@
 extern u64 perf_swevent_set_period(struct perf_event *event);
 extern void perf_event_enable(struct perf_event *event);
 extern void perf_event_disable(struct perf_event *event);
-extern int __perf_event_disable(void *info);
+extern void perf_event_disable_local(struct perf_event *event);
 extern void perf_event_task_tick(void);
 #else /* !CONFIG_PERF_EVENTS: */
 static inline void *
@@ -1070,7 +1067,7 @@
 static inline void perf_event_exit_task(struct task_struct *child)	{ }
 static inline void perf_event_free_task(struct task_struct *task)	{ }
 static inline void perf_event_delayed_put(struct task_struct *task)	{ }
-static inline struct perf_event *perf_event_get(unsigned int fd)	{ return ERR_PTR(-EINVAL); }
+static inline struct file *perf_event_get(unsigned int fd)	{ return ERR_PTR(-EINVAL); }
 static inline const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
 {
 	return ERR_PTR(-EINVAL);
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index b0799bc..89ebbc4 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -291,10 +291,13 @@
 {
 	struct perf_event *event;
 	const struct perf_event_attr *attr;
+	struct file *file;
 
-	event = perf_event_get(fd);
-	if (IS_ERR(event))
-		return event;
+	file = perf_event_get(fd);
+	if (IS_ERR(file))
+		return file;
+
+	event = file->private_data;
 
 	attr = perf_event_attrs(event);
 	if (IS_ERR(attr))
@@ -304,24 +307,22 @@
 		goto err;
 
 	if (attr->type == PERF_TYPE_RAW)
-		return event;
+		return file;
 
 	if (attr->type == PERF_TYPE_HARDWARE)
-		return event;
+		return file;
 
 	if (attr->type == PERF_TYPE_SOFTWARE &&
 	    attr->config == PERF_COUNT_SW_BPF_OUTPUT)
-		return event;
+		return file;
 err:
-	perf_event_release_kernel(event);
+	fput(file);
 	return ERR_PTR(-EINVAL);
 }
 
 static void perf_event_fd_array_put_ptr(void *ptr)
 {
-	struct perf_event *event = ptr;
-
-	perf_event_release_kernel(event);
+	fput((struct file *)ptr);
 }
 
 static const struct bpf_map_ops perf_event_array_ops = {
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 06ae52e..5946460 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -49,8 +49,6 @@
 
 #include <asm/irq_regs.h>
 
-static struct workqueue_struct *perf_wq;
-
 typedef int (*remote_function_f)(void *);
 
 struct remote_function_call {
@@ -126,44 +124,181 @@
 	return data.ret;
 }
 
-static void event_function_call(struct perf_event *event,
-				int (*active)(void *),
-				void (*inactive)(void *),
-				void *data)
+static inline struct perf_cpu_context *
+__get_cpu_context(struct perf_event_context *ctx)
+{
+	return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
+}
+
+static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
+			  struct perf_event_context *ctx)
+{
+	raw_spin_lock(&cpuctx->ctx.lock);
+	if (ctx)
+		raw_spin_lock(&ctx->lock);
+}
+
+static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
+			    struct perf_event_context *ctx)
+{
+	if (ctx)
+		raw_spin_unlock(&ctx->lock);
+	raw_spin_unlock(&cpuctx->ctx.lock);
+}
+
+#define TASK_TOMBSTONE ((void *)-1L)
+
+static bool is_kernel_event(struct perf_event *event)
+{
+	return READ_ONCE(event->owner) == TASK_TOMBSTONE;
+}
+
+/*
+ * On task ctx scheduling...
+ *
+ * When !ctx->nr_events a task context will not be scheduled. This means
+ * we can disable the scheduler hooks (for performance) without leaving
+ * pending task ctx state.
+ *
+ * This however results in two special cases:
+ *
+ *  - removing the last event from a task ctx; this is relatively straight
+ *    forward and is done in __perf_remove_from_context.
+ *
+ *  - adding the first event to a task ctx; this is tricky because we cannot
+ *    rely on ctx->is_active and therefore cannot use event_function_call().
+ *    See perf_install_in_context().
+ *
+ * This is because we need a ctx->lock serialized variable (ctx->is_active)
+ * to reliably determine if a particular task/context is scheduled in. The
+ * task_curr() use in task_function_call() is racy in that a remote context
+ * switch is not a single atomic operation.
+ *
+ * As is, the situation is 'safe' because we set rq->curr before we do the
+ * actual context switch. This means that task_curr() will fail early, but
+ * we'll continue spinning on ctx->is_active until we've passed
+ * perf_event_task_sched_out().
+ *
+ * Without this ctx->lock serialized variable we could have race where we find
+ * the task (and hence the context) would not be active while in fact they are.
+ *
+ * If ctx->nr_events, then ctx->is_active and cpuctx->task_ctx are set.
+ */
+
+typedef void (*event_f)(struct perf_event *, struct perf_cpu_context *,
+			struct perf_event_context *, void *);
+
+struct event_function_struct {
+	struct perf_event *event;
+	event_f func;
+	void *data;
+};
+
+static int event_function(void *info)
+{
+	struct event_function_struct *efs = info;
+	struct perf_event *event = efs->event;
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event_context *task_ctx = cpuctx->task_ctx;
+	int ret = 0;
+
+	WARN_ON_ONCE(!irqs_disabled());
+
+	perf_ctx_lock(cpuctx, task_ctx);
+	/*
+	 * Since we do the IPI call without holding ctx->lock things can have
+	 * changed, double check we hit the task we set out to hit.
+	 */
+	if (ctx->task) {
+		if (ctx->task != current) {
+			ret = -EAGAIN;
+			goto unlock;
+		}
+
+		/*
+		 * We only use event_function_call() on established contexts,
+		 * and event_function() is only ever called when active (or
+		 * rather, we'll have bailed in task_function_call() or the
+		 * above ctx->task != current test), therefore we must have
+		 * ctx->is_active here.
+		 */
+		WARN_ON_ONCE(!ctx->is_active);
+		/*
+		 * And since we have ctx->is_active, cpuctx->task_ctx must
+		 * match.
+		 */
+		WARN_ON_ONCE(task_ctx != ctx);
+	} else {
+		WARN_ON_ONCE(&cpuctx->ctx != ctx);
+	}
+
+	efs->func(event, cpuctx, ctx, efs->data);
+unlock:
+	perf_ctx_unlock(cpuctx, task_ctx);
+
+	return ret;
+}
+
+static void event_function_local(struct perf_event *event, event_f func, void *data)
+{
+	struct event_function_struct efs = {
+		.event = event,
+		.func = func,
+		.data = data,
+	};
+
+	int ret = event_function(&efs);
+	WARN_ON_ONCE(ret);
+}
+
+static void event_function_call(struct perf_event *event, event_f func, void *data)
 {
 	struct perf_event_context *ctx = event->ctx;
-	struct task_struct *task = ctx->task;
+	struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
+	struct event_function_struct efs = {
+		.event = event,
+		.func = func,
+		.data = data,
+	};
+
+	if (!event->parent) {
+		/*
+		 * If this is a !child event, we must hold ctx::mutex to
+		 * stabilize the the event->ctx relation. See
+		 * perf_event_ctx_lock().
+		 */
+		lockdep_assert_held(&ctx->mutex);
+	}
 
 	if (!task) {
-		cpu_function_call(event->cpu, active, data);
+		cpu_function_call(event->cpu, event_function, &efs);
 		return;
 	}
 
 again:
-	if (!task_function_call(task, active, data))
+	if (task == TASK_TOMBSTONE)
+		return;
+
+	if (!task_function_call(task, event_function, &efs))
 		return;
 
 	raw_spin_lock_irq(&ctx->lock);
-	if (ctx->is_active) {
-		/*
-		 * Reload the task pointer, it might have been changed by
-		 * a concurrent perf_event_context_sched_out().
-		 */
-		task = ctx->task;
-		raw_spin_unlock_irq(&ctx->lock);
-		goto again;
+	/*
+	 * Reload the task pointer, it might have been changed by
+	 * a concurrent perf_event_context_sched_out().
+	 */
+	task = ctx->task;
+	if (task != TASK_TOMBSTONE) {
+		if (ctx->is_active) {
+			raw_spin_unlock_irq(&ctx->lock);
+			goto again;
+		}
+		func(event, NULL, ctx, data);
 	}
-	inactive(data);
 	raw_spin_unlock_irq(&ctx->lock);
 }
 
-#define EVENT_OWNER_KERNEL ((void *) -1)
-
-static bool is_kernel_event(struct perf_event *event)
-{
-	return event->owner == EVENT_OWNER_KERNEL;
-}
-
 #define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
 		       PERF_FLAG_FD_OUTPUT  |\
 		       PERF_FLAG_PID_CGROUP |\
@@ -368,28 +503,6 @@
 	return event->clock();
 }
 
-static inline struct perf_cpu_context *
-__get_cpu_context(struct perf_event_context *ctx)
-{
-	return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
-}
-
-static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
-			  struct perf_event_context *ctx)
-{
-	raw_spin_lock(&cpuctx->ctx.lock);
-	if (ctx)
-		raw_spin_lock(&ctx->lock);
-}
-
-static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
-			    struct perf_event_context *ctx)
-{
-	if (ctx)
-		raw_spin_unlock(&ctx->lock);
-	raw_spin_unlock(&cpuctx->ctx.lock);
-}
-
 #ifdef CONFIG_CGROUP_PERF
 
 static inline bool
@@ -579,13 +692,7 @@
 	 * we are holding the rcu lock
 	 */
 	cgrp1 = perf_cgroup_from_task(task, NULL);
-
-	/*
-	 * next is NULL when called from perf_event_enable_on_exec()
-	 * that will systematically cause a cgroup_switch()
-	 */
-	if (next)
-		cgrp2 = perf_cgroup_from_task(next, NULL);
+	cgrp2 = perf_cgroup_from_task(next, NULL);
 
 	/*
 	 * only schedule out current cgroup events if we know
@@ -611,8 +718,6 @@
 	 * we are holding the rcu lock
 	 */
 	cgrp1 = perf_cgroup_from_task(task, NULL);
-
-	/* prev can never be NULL */
 	cgrp2 = perf_cgroup_from_task(prev, NULL);
 
 	/*
@@ -917,7 +1022,7 @@
 	if (atomic_dec_and_test(&ctx->refcount)) {
 		if (ctx->parent_ctx)
 			put_ctx(ctx->parent_ctx);
-		if (ctx->task)
+		if (ctx->task && ctx->task != TASK_TOMBSTONE)
 			put_task_struct(ctx->task);
 		call_rcu(&ctx->rcu_head, free_ctx);
 	}
@@ -934,9 +1039,8 @@
  * perf_event_context::mutex nests and those are:
  *
  *  - perf_event_exit_task_context()	[ child , 0 ]
- *      __perf_event_exit_task()
- *        sync_child_event()
- *          put_event()			[ parent, 1 ]
+ *      perf_event_exit_event()
+ *        put_event()			[ parent, 1 ]
  *
  *  - perf_event_init_context()		[ parent, 0 ]
  *      inherit_task_group()
@@ -979,8 +1083,8 @@
  * Lock order:
  *	task_struct::perf_event_mutex
  *	  perf_event_context::mutex
- *	    perf_event_context::lock
  *	    perf_event::child_mutex;
+ *	      perf_event_context::lock
  *	    perf_event::mmap_mutex
  *	    mmap_sem
  */
@@ -1078,6 +1182,7 @@
 
 /*
  * Get the perf_event_context for a task and lock it.
+ *
  * This has to cope with with the fact that until it is locked,
  * the context could get moved to another task.
  */
@@ -1118,9 +1223,12 @@
 			goto retry;
 		}
 
-		if (!atomic_inc_not_zero(&ctx->refcount)) {
+		if (ctx->task == TASK_TOMBSTONE ||
+		    !atomic_inc_not_zero(&ctx->refcount)) {
 			raw_spin_unlock(&ctx->lock);
 			ctx = NULL;
+		} else {
+			WARN_ON_ONCE(ctx->task != task);
 		}
 	}
 	rcu_read_unlock();
@@ -1246,6 +1354,8 @@
 static void
 list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 {
+	lockdep_assert_held(&ctx->lock);
+
 	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
 	event->attach_state |= PERF_ATTACH_CONTEXT;
 
@@ -1448,11 +1558,14 @@
 
 	if (is_cgroup_event(event)) {
 		ctx->nr_cgroups--;
+		/*
+		 * Because cgroup events are always per-cpu events, this will
+		 * always be called from the right CPU.
+		 */
 		cpuctx = __get_cpu_context(ctx);
 		/*
-		 * if there are no more cgroup events
-		 * then cler cgrp to avoid stale pointer
-		 * in update_cgrp_time_from_cpuctx()
+		 * If there are no more cgroup events then clear cgrp to avoid
+		 * stale pointer in update_cgrp_time_from_cpuctx().
 		 */
 		if (!ctx->nr_cgroups)
 			cpuctx->cgrp = NULL;
@@ -1530,45 +1643,11 @@
 		perf_event__header_size(tmp);
 }
 
-/*
- * User event without the task.
- */
 static bool is_orphaned_event(struct perf_event *event)
 {
-	return event && !is_kernel_event(event) && !event->owner;
+	return event->state == PERF_EVENT_STATE_EXIT;
 }
 
-/*
- * Event has a parent but parent's task finished and it's
- * alive only because of children holding refference.
- */
-static bool is_orphaned_child(struct perf_event *event)
-{
-	return is_orphaned_event(event->parent);
-}
-
-static void orphans_remove_work(struct work_struct *work);
-
-static void schedule_orphans_remove(struct perf_event_context *ctx)
-{
-	if (!ctx->task || ctx->orphans_remove_sched || !perf_wq)
-		return;
-
-	if (queue_delayed_work(perf_wq, &ctx->orphans_remove, 1)) {
-		get_ctx(ctx);
-		ctx->orphans_remove_sched = true;
-	}
-}
-
-static int __init perf_workqueue_init(void)
-{
-	perf_wq = create_singlethread_workqueue("perf");
-	WARN(!perf_wq, "failed to create perf workqueue\n");
-	return perf_wq ? 0 : -1;
-}
-
-core_initcall(perf_workqueue_init);
-
 static inline int pmu_filter_match(struct perf_event *event)
 {
 	struct pmu *pmu = event->pmu;
@@ -1629,9 +1708,6 @@
 	if (event->attr.exclusive || !cpuctx->active_oncpu)
 		cpuctx->exclusive = 0;
 
-	if (is_orphaned_child(event))
-		schedule_orphans_remove(ctx);
-
 	perf_pmu_enable(event->pmu);
 }
 
@@ -1655,21 +1731,8 @@
 		cpuctx->exclusive = 0;
 }
 
-struct remove_event {
-	struct perf_event *event;
-	bool detach_group;
-};
-
-static void ___perf_remove_from_context(void *info)
-{
-	struct remove_event *re = info;
-	struct perf_event *event = re->event;
-	struct perf_event_context *ctx = event->ctx;
-
-	if (re->detach_group)
-		perf_group_detach(event);
-	list_del_event(event, ctx);
-}
+#define DETACH_GROUP	0x01UL
+#define DETACH_STATE	0x02UL
 
 /*
  * Cross CPU call to remove a performance event
@@ -1677,33 +1740,33 @@
  * We disable the event on the hardware level first. After that we
  * remove it from the context list.
  */
-static int __perf_remove_from_context(void *info)
+static void
+__perf_remove_from_context(struct perf_event *event,
+			   struct perf_cpu_context *cpuctx,
+			   struct perf_event_context *ctx,
+			   void *info)
 {
-	struct remove_event *re = info;
-	struct perf_event *event = re->event;
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	unsigned long flags = (unsigned long)info;
 
-	raw_spin_lock(&ctx->lock);
 	event_sched_out(event, cpuctx, ctx);
-	if (re->detach_group)
+	if (flags & DETACH_GROUP)
 		perf_group_detach(event);
 	list_del_event(event, ctx);
-	if (!ctx->nr_events && cpuctx->task_ctx == ctx) {
-		ctx->is_active = 0;
-		cpuctx->task_ctx = NULL;
-	}
-	raw_spin_unlock(&ctx->lock);
+	if (flags & DETACH_STATE)
+		event->state = PERF_EVENT_STATE_EXIT;
 
-	return 0;
+	if (!ctx->nr_events && ctx->is_active) {
+		ctx->is_active = 0;
+		if (ctx->task) {
+			WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+			cpuctx->task_ctx = NULL;
+		}
+	}
 }
 
 /*
  * Remove the event from a task's (or a CPU's) list of events.
  *
- * CPU events are removed with a smp call. For task events we only
- * call when the task is on a CPU.
- *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This is OK when called from perf_release since
@@ -1711,73 +1774,32 @@
  * When called from perf_event_exit_task, it's OK because the
  * context has been detached from its task.
  */
-static void perf_remove_from_context(struct perf_event *event, bool detach_group)
+static void perf_remove_from_context(struct perf_event *event, unsigned long flags)
 {
-	struct perf_event_context *ctx = event->ctx;
-	struct remove_event re = {
-		.event = event,
-		.detach_group = detach_group,
-	};
+	lockdep_assert_held(&event->ctx->mutex);
 
-	lockdep_assert_held(&ctx->mutex);
-
-	event_function_call(event, __perf_remove_from_context,
-			    ___perf_remove_from_context, &re);
+	event_function_call(event, __perf_remove_from_context, (void *)flags);
 }
 
 /*
  * Cross CPU call to disable a performance event
  */
-int __perf_event_disable(void *info)
+static void __perf_event_disable(struct perf_event *event,
+				 struct perf_cpu_context *cpuctx,
+				 struct perf_event_context *ctx,
+				 void *info)
 {
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
+		return;
 
-	/*
-	 * If this is a per-task event, need to check whether this
-	 * event's task is the current task on this cpu.
-	 *
-	 * Can trigger due to concurrent perf_event_context_sched_out()
-	 * flipping contexts around.
-	 */
-	if (ctx->task && cpuctx->task_ctx != ctx)
-		return -EINVAL;
-
-	raw_spin_lock(&ctx->lock);
-
-	/*
-	 * If the event is on, turn it off.
-	 * If it is in error state, leave it in error state.
-	 */
-	if (event->state >= PERF_EVENT_STATE_INACTIVE) {
-		update_context_time(ctx);
-		update_cgrp_time_from_event(event);
-		update_group_times(event);
-		if (event == event->group_leader)
-			group_sched_out(event, cpuctx, ctx);
-		else
-			event_sched_out(event, cpuctx, ctx);
-		event->state = PERF_EVENT_STATE_OFF;
-	}
-
-	raw_spin_unlock(&ctx->lock);
-
-	return 0;
-}
-
-void ___perf_event_disable(void *info)
-{
-	struct perf_event *event = info;
-
-	/*
-	 * Since we have the lock this context can't be scheduled
-	 * in, so we can change the state safely.
-	 */
-	if (event->state == PERF_EVENT_STATE_INACTIVE) {
-		update_group_times(event);
-		event->state = PERF_EVENT_STATE_OFF;
-	}
+	update_context_time(ctx);
+	update_cgrp_time_from_event(event);
+	update_group_times(event);
+	if (event == event->group_leader)
+		group_sched_out(event, cpuctx, ctx);
+	else
+		event_sched_out(event, cpuctx, ctx);
+	event->state = PERF_EVENT_STATE_OFF;
 }
 
 /*
@@ -1788,7 +1810,8 @@
  * remains valid.  This condition is satisifed when called through
  * perf_event_for_each_child or perf_event_for_each because they
  * hold the top-level event's child_mutex, so any descendant that
- * goes to exit will block in sync_child_event.
+ * goes to exit will block in perf_event_exit_event().
+ *
  * When called from perf_pending_event it's OK because event->ctx
  * is the current context on this CPU and preemption is disabled,
  * hence we can't get into perf_event_task_sched_out for this context.
@@ -1804,8 +1827,12 @@
 	}
 	raw_spin_unlock_irq(&ctx->lock);
 
-	event_function_call(event, __perf_event_disable,
-			    ___perf_event_disable, event);
+	event_function_call(event, __perf_event_disable, NULL);
+}
+
+void perf_event_disable_local(struct perf_event *event)
+{
+	event_function_local(event, __perf_event_disable, NULL);
 }
 
 /*
@@ -1918,9 +1945,6 @@
 	if (event->attr.exclusive)
 		cpuctx->exclusive = 1;
 
-	if (is_orphaned_child(event))
-		schedule_orphans_remove(ctx);
-
 out:
 	perf_pmu_enable(event->pmu);
 
@@ -2039,7 +2063,8 @@
 	event->tstamp_stopped = tstamp;
 }
 
-static void task_ctx_sched_out(struct perf_event_context *ctx);
+static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			       struct perf_event_context *ctx);
 static void
 ctx_sched_in(struct perf_event_context *ctx,
 	     struct perf_cpu_context *cpuctx,
@@ -2058,16 +2083,15 @@
 		ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE, task);
 }
 
-static void ___perf_install_in_context(void *info)
+static void ctx_resched(struct perf_cpu_context *cpuctx,
+			struct perf_event_context *task_ctx)
 {
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
-
-	/*
-	 * Since the task isn't running, its safe to add the event, us holding
-	 * the ctx->lock ensures the task won't get scheduled in.
-	 */
-	add_event_to_ctx(event, ctx);
+	perf_pmu_disable(cpuctx->ctx.pmu);
+	if (task_ctx)
+		task_ctx_sched_out(cpuctx, task_ctx);
+	cpu_ctx_sched_out(cpuctx, EVENT_ALL);
+	perf_event_sched_in(cpuctx, task_ctx, current);
+	perf_pmu_enable(cpuctx->ctx.pmu);
 }
 
 /*
@@ -2077,55 +2101,31 @@
  */
 static int  __perf_install_in_context(void *info)
 {
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
+	struct perf_event_context *ctx = info;
 	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 	struct perf_event_context *task_ctx = cpuctx->task_ctx;
-	struct task_struct *task = current;
 
-	perf_ctx_lock(cpuctx, task_ctx);
-	perf_pmu_disable(cpuctx->ctx.pmu);
-
-	/*
-	 * If there was an active task_ctx schedule it out.
-	 */
-	if (task_ctx)
-		task_ctx_sched_out(task_ctx);
-
-	/*
-	 * If the context we're installing events in is not the
-	 * active task_ctx, flip them.
-	 */
-	if (ctx->task && task_ctx != ctx) {
-		if (task_ctx)
-			raw_spin_unlock(&task_ctx->lock);
+	raw_spin_lock(&cpuctx->ctx.lock);
+	if (ctx->task) {
 		raw_spin_lock(&ctx->lock);
+		/*
+		 * If we hit the 'wrong' task, we've since scheduled and
+		 * everything should be sorted, nothing to do!
+		 */
 		task_ctx = ctx;
+		if (ctx->task != current)
+			goto unlock;
+
+		/*
+		 * If task_ctx is set, it had better be to us.
+		 */
+		WARN_ON_ONCE(cpuctx->task_ctx != ctx && cpuctx->task_ctx);
+	} else if (task_ctx) {
+		raw_spin_lock(&task_ctx->lock);
 	}
 
-	if (task_ctx) {
-		cpuctx->task_ctx = task_ctx;
-		task = task_ctx->task;
-	}
-
-	cpu_ctx_sched_out(cpuctx, EVENT_ALL);
-
-	update_context_time(ctx);
-	/*
-	 * update cgrp time only if current cgrp
-	 * matches event->cgrp. Must be done before
-	 * calling add_event_to_ctx()
-	 */
-	update_cgrp_time_from_event(event);
-
-	add_event_to_ctx(event, ctx);
-
-	/*
-	 * Schedule everything back in
-	 */
-	perf_event_sched_in(cpuctx, task_ctx, task);
-
-	perf_pmu_enable(cpuctx->ctx.pmu);
+	ctx_resched(cpuctx, task_ctx);
+unlock:
 	perf_ctx_unlock(cpuctx, task_ctx);
 
 	return 0;
@@ -2133,27 +2133,54 @@
 
 /*
  * Attach a performance event to a context
- *
- * First we add the event to the list with the hardware enable bit
- * in event->hw_config cleared.
- *
- * If the event is attached to a task which is on a CPU we use a smp
- * call to enable it in the task context. The task might have been
- * scheduled away, but we check this in the smp call again.
  */
 static void
 perf_install_in_context(struct perf_event_context *ctx,
 			struct perf_event *event,
 			int cpu)
 {
+	struct task_struct *task = NULL;
+
 	lockdep_assert_held(&ctx->mutex);
 
 	event->ctx = ctx;
 	if (event->cpu != -1)
 		event->cpu = cpu;
 
-	event_function_call(event, __perf_install_in_context,
-			    ___perf_install_in_context, event);
+	/*
+	 * Installing events is tricky because we cannot rely on ctx->is_active
+	 * to be set in case this is the nr_events 0 -> 1 transition.
+	 *
+	 * So what we do is we add the event to the list here, which will allow
+	 * a future context switch to DTRT and then send a racy IPI. If the IPI
+	 * fails to hit the right task, this means a context switch must have
+	 * happened and that will have taken care of business.
+	 */
+	raw_spin_lock_irq(&ctx->lock);
+	task = ctx->task;
+	/*
+	 * Worse, we cannot even rely on the ctx actually existing anymore. If
+	 * between find_get_context() and perf_install_in_context() the task
+	 * went through perf_event_exit_task() its dead and we should not be
+	 * adding new events.
+	 */
+	if (task == TASK_TOMBSTONE) {
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+	update_context_time(ctx);
+	/*
+	 * Update cgrp time only if current cgrp matches event->cgrp.
+	 * Must be done before calling add_event_to_ctx().
+	 */
+	update_cgrp_time_from_event(event);
+	add_event_to_ctx(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+
+	if (task)
+		task_function_call(task, __perf_install_in_context, ctx);
+	else
+		cpu_function_call(cpu, __perf_install_in_context, ctx);
 }
 
 /*
@@ -2180,43 +2207,30 @@
 /*
  * Cross CPU call to enable a performance event
  */
-static int __perf_event_enable(void *info)
+static void __perf_event_enable(struct perf_event *event,
+				struct perf_cpu_context *cpuctx,
+				struct perf_event_context *ctx,
+				void *info)
 {
-	struct perf_event *event = info;
-	struct perf_event_context *ctx = event->ctx;
 	struct perf_event *leader = event->group_leader;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
-	int err;
+	struct perf_event_context *task_ctx;
 
-	/*
-	 * There's a time window between 'ctx->is_active' check
-	 * in perf_event_enable function and this place having:
-	 *   - IRQs on
-	 *   - ctx->lock unlocked
-	 *
-	 * where the task could be killed and 'ctx' deactivated
-	 * by perf_event_exit_task.
-	 */
-	if (!ctx->is_active)
-		return -EINVAL;
+	if (event->state >= PERF_EVENT_STATE_INACTIVE ||
+	    event->state <= PERF_EVENT_STATE_ERROR)
+		return;
 
-	raw_spin_lock(&ctx->lock);
 	update_context_time(ctx);
-
-	if (event->state >= PERF_EVENT_STATE_INACTIVE)
-		goto unlock;
-
-	/*
-	 * set current task's cgroup time reference point
-	 */
-	perf_cgroup_set_timestamp(current, ctx);
-
 	__perf_event_mark_enabled(event);
 
+	if (!ctx->is_active)
+		return;
+
 	if (!event_filter_match(event)) {
-		if (is_cgroup_event(event))
+		if (is_cgroup_event(event)) {
+			perf_cgroup_set_timestamp(current, ctx); // XXX ?
 			perf_cgroup_defer_enabled(event);
-		goto unlock;
+		}
+		return;
 	}
 
 	/*
@@ -2224,41 +2238,13 @@
 	 * then don't put it on unless the group is on.
 	 */
 	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
-		goto unlock;
+		return;
 
-	if (!group_can_go_on(event, cpuctx, 1)) {
-		err = -EEXIST;
-	} else {
-		if (event == leader)
-			err = group_sched_in(event, cpuctx, ctx);
-		else
-			err = event_sched_in(event, cpuctx, ctx);
-	}
+	task_ctx = cpuctx->task_ctx;
+	if (ctx->task)
+		WARN_ON_ONCE(task_ctx != ctx);
 
-	if (err) {
-		/*
-		 * If this event can't go on and it's part of a
-		 * group, then the whole group has to come off.
-		 */
-		if (leader != event) {
-			group_sched_out(leader, cpuctx, ctx);
-			perf_mux_hrtimer_restart(cpuctx);
-		}
-		if (leader->attr.pinned) {
-			update_group_times(leader);
-			leader->state = PERF_EVENT_STATE_ERROR;
-		}
-	}
-
-unlock:
-	raw_spin_unlock(&ctx->lock);
-
-	return 0;
-}
-
-void ___perf_event_enable(void *info)
-{
-	__perf_event_mark_enabled((struct perf_event *)info);
+	ctx_resched(cpuctx, task_ctx);
 }
 
 /*
@@ -2275,7 +2261,8 @@
 	struct perf_event_context *ctx = event->ctx;
 
 	raw_spin_lock_irq(&ctx->lock);
-	if (event->state >= PERF_EVENT_STATE_INACTIVE) {
+	if (event->state >= PERF_EVENT_STATE_INACTIVE ||
+	    event->state <  PERF_EVENT_STATE_ERROR) {
 		raw_spin_unlock_irq(&ctx->lock);
 		return;
 	}
@@ -2291,8 +2278,7 @@
 		event->state = PERF_EVENT_STATE_OFF;
 	raw_spin_unlock_irq(&ctx->lock);
 
-	event_function_call(event, __perf_event_enable,
-			    ___perf_event_enable, event);
+	event_function_call(event, __perf_event_enable, NULL);
 }
 
 /*
@@ -2342,12 +2328,27 @@
 			  struct perf_cpu_context *cpuctx,
 			  enum event_type_t event_type)
 {
-	struct perf_event *event;
 	int is_active = ctx->is_active;
+	struct perf_event *event;
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (likely(!ctx->nr_events)) {
+		/*
+		 * See __perf_remove_from_context().
+		 */
+		WARN_ON_ONCE(ctx->is_active);
+		if (ctx->task)
+			WARN_ON_ONCE(cpuctx->task_ctx);
+		return;
+	}
 
 	ctx->is_active &= ~event_type;
-	if (likely(!ctx->nr_events))
-		return;
+	if (ctx->task) {
+		WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+		if (!ctx->is_active)
+			cpuctx->task_ctx = NULL;
+	}
 
 	update_context_time(ctx);
 	update_cgrp_time_from_cpuctx(cpuctx);
@@ -2518,17 +2519,21 @@
 		raw_spin_lock(&ctx->lock);
 		raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
 		if (context_equiv(ctx, next_ctx)) {
-			/*
-			 * XXX do we need a memory barrier of sorts
-			 * wrt to rcu_dereference() of perf_event_ctxp
-			 */
-			task->perf_event_ctxp[ctxn] = next_ctx;
-			next->perf_event_ctxp[ctxn] = ctx;
-			ctx->task = next;
-			next_ctx->task = task;
+			WRITE_ONCE(ctx->task, next);
+			WRITE_ONCE(next_ctx->task, task);
 
 			swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
 
+			/*
+			 * RCU_INIT_POINTER here is safe because we've not
+			 * modified the ctx and the above modification of
+			 * ctx->task and ctx->task_ctx_data are immaterial
+			 * since those values are always verified under
+			 * ctx->lock which we're now holding.
+			 */
+			RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], next_ctx);
+			RCU_INIT_POINTER(next->perf_event_ctxp[ctxn], ctx);
+
 			do_switch = 0;
 
 			perf_event_sync_stat(ctx, next_ctx);
@@ -2541,8 +2546,7 @@
 
 	if (do_switch) {
 		raw_spin_lock(&ctx->lock);
-		ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-		cpuctx->task_ctx = NULL;
+		task_ctx_sched_out(cpuctx, ctx);
 		raw_spin_unlock(&ctx->lock);
 	}
 }
@@ -2637,10 +2641,9 @@
 		perf_cgroup_sched_out(task, next);
 }
 
-static void task_ctx_sched_out(struct perf_event_context *ctx)
+static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			       struct perf_event_context *ctx)
 {
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
-
 	if (!cpuctx->task_ctx)
 		return;
 
@@ -2648,7 +2651,6 @@
 		return;
 
 	ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-	cpuctx->task_ctx = NULL;
 }
 
 /*
@@ -2725,13 +2727,22 @@
 	     enum event_type_t event_type,
 	     struct task_struct *task)
 {
-	u64 now;
 	int is_active = ctx->is_active;
+	u64 now;
 
-	ctx->is_active |= event_type;
+	lockdep_assert_held(&ctx->lock);
+
 	if (likely(!ctx->nr_events))
 		return;
 
+	ctx->is_active |= event_type;
+	if (ctx->task) {
+		if (!is_active)
+			cpuctx->task_ctx = ctx;
+		else
+			WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+	}
+
 	now = perf_clock();
 	ctx->timestamp = now;
 	perf_cgroup_set_timestamp(task, ctx);
@@ -2773,12 +2784,7 @@
 	 * cpu flexible, task flexible.
 	 */
 	cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
-
-	if (ctx->nr_events)
-		cpuctx->task_ctx = ctx;
-
-	perf_event_sched_in(cpuctx, cpuctx->task_ctx, task);
-
+	perf_event_sched_in(cpuctx, ctx, task);
 	perf_pmu_enable(ctx->pmu);
 	perf_ctx_unlock(cpuctx, ctx);
 }
@@ -2800,6 +2806,16 @@
 	struct perf_event_context *ctx;
 	int ctxn;
 
+	/*
+	 * If cgroup events exist on this CPU, then we need to check if we have
+	 * to switch in PMU state; cgroup event are system-wide mode only.
+	 *
+	 * Since cgroup events are CPU events, we must schedule these in before
+	 * we schedule in the task events.
+	 */
+	if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
+		perf_cgroup_sched_in(prev, task);
+
 	for_each_task_context_nr(ctxn) {
 		ctx = task->perf_event_ctxp[ctxn];
 		if (likely(!ctx))
@@ -2807,13 +2823,6 @@
 
 		perf_event_context_sched_in(ctx, task);
 	}
-	/*
-	 * if cgroup events exist on this CPU, then we need
-	 * to check if we have to switch in PMU state.
-	 * cgroup event are system-wide mode only
-	 */
-	if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
-		perf_cgroup_sched_in(prev, task);
 
 	if (atomic_read(&nr_switch_events))
 		perf_event_switch(task, prev, true);
@@ -3099,46 +3108,30 @@
 static void perf_event_enable_on_exec(int ctxn)
 {
 	struct perf_event_context *ctx, *clone_ctx = NULL;
+	struct perf_cpu_context *cpuctx;
 	struct perf_event *event;
 	unsigned long flags;
 	int enabled = 0;
-	int ret;
 
 	local_irq_save(flags);
 	ctx = current->perf_event_ctxp[ctxn];
 	if (!ctx || !ctx->nr_events)
 		goto out;
 
-	/*
-	 * We must ctxsw out cgroup events to avoid conflict
-	 * when invoking perf_task_event_sched_in() later on
-	 * in this function. Otherwise we end up trying to
-	 * ctxswin cgroup events which are already scheduled
-	 * in.
-	 */
-	perf_cgroup_sched_out(current, NULL);
-
-	raw_spin_lock(&ctx->lock);
-	task_ctx_sched_out(ctx);
-
-	list_for_each_entry(event, &ctx->event_list, event_entry) {
-		ret = event_enable_on_exec(event, ctx);
-		if (ret)
-			enabled = 1;
-	}
+	cpuctx = __get_cpu_context(ctx);
+	perf_ctx_lock(cpuctx, ctx);
+	list_for_each_entry(event, &ctx->event_list, event_entry)
+		enabled |= event_enable_on_exec(event, ctx);
 
 	/*
-	 * Unclone this context if we enabled any event.
+	 * Unclone and reschedule this context if we enabled any event.
 	 */
-	if (enabled)
+	if (enabled) {
 		clone_ctx = unclone_ctx(ctx);
+		ctx_resched(cpuctx, ctx);
+	}
+	perf_ctx_unlock(cpuctx, ctx);
 
-	raw_spin_unlock(&ctx->lock);
-
-	/*
-	 * Also calls ctxswin for cgroup events, if any:
-	 */
-	perf_event_context_sched_in(ctx, ctx->task);
 out:
 	local_irq_restore(flags);
 
@@ -3334,7 +3327,6 @@
 	INIT_LIST_HEAD(&ctx->flexible_groups);
 	INIT_LIST_HEAD(&ctx->event_list);
 	atomic_set(&ctx->refcount, 1);
-	INIT_DELAYED_WORK(&ctx->orphans_remove, orphans_remove_work);
 }
 
 static struct perf_event_context *
@@ -3521,11 +3513,13 @@
 
 static void unaccount_event(struct perf_event *event)
 {
+	bool dec = false;
+
 	if (event->parent)
 		return;
 
 	if (event->attach_state & PERF_ATTACH_TASK)
-		static_key_slow_dec_deferred(&perf_sched_events);
+		dec = true;
 	if (event->attr.mmap || event->attr.mmap_data)
 		atomic_dec(&nr_mmap_events);
 	if (event->attr.comm)
@@ -3535,12 +3529,15 @@
 	if (event->attr.freq)
 		atomic_dec(&nr_freq_events);
 	if (event->attr.context_switch) {
-		static_key_slow_dec_deferred(&perf_sched_events);
+		dec = true;
 		atomic_dec(&nr_switch_events);
 	}
 	if (is_cgroup_event(event))
-		static_key_slow_dec_deferred(&perf_sched_events);
+		dec = true;
 	if (has_branch_stack(event))
+		dec = true;
+
+	if (dec)
 		static_key_slow_dec_deferred(&perf_sched_events);
 
 	unaccount_event_cpu(event, event->cpu);
@@ -3556,7 +3553,7 @@
  *  3) two matching events on the same context.
  *
  * The former two cases are handled in the allocation path (perf_event_alloc(),
- * __free_event()), the latter -- before the first perf_install_in_context().
+ * _free_event()), the latter -- before the first perf_install_in_context().
  */
 static int exclusive_event_init(struct perf_event *event)
 {
@@ -3631,29 +3628,6 @@
 	return true;
 }
 
-static void __free_event(struct perf_event *event)
-{
-	if (!event->parent) {
-		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
-			put_callchain_buffers();
-	}
-
-	perf_event_free_bpf_prog(event);
-
-	if (event->destroy)
-		event->destroy(event);
-
-	if (event->ctx)
-		put_ctx(event->ctx);
-
-	if (event->pmu) {
-		exclusive_event_destroy(event);
-		module_put(event->pmu->module);
-	}
-
-	call_rcu(&event->rcu_head, free_event_rcu);
-}
-
 static void _free_event(struct perf_event *event)
 {
 	irq_work_sync(&event->pending);
@@ -3675,7 +3649,25 @@
 	if (is_cgroup_event(event))
 		perf_detach_cgroup(event);
 
-	__free_event(event);
+	if (!event->parent) {
+		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+			put_callchain_buffers();
+	}
+
+	perf_event_free_bpf_prog(event);
+
+	if (event->destroy)
+		event->destroy(event);
+
+	if (event->ctx)
+		put_ctx(event->ctx);
+
+	if (event->pmu) {
+		exclusive_event_destroy(event);
+		module_put(event->pmu->module);
+	}
+
+	call_rcu(&event->rcu_head, free_event_rcu);
 }
 
 /*
@@ -3702,14 +3694,13 @@
 	struct task_struct *owner;
 
 	rcu_read_lock();
-	owner = ACCESS_ONCE(event->owner);
 	/*
-	 * Matches the smp_wmb() in perf_event_exit_task(). If we observe
-	 * !owner it means the list deletion is complete and we can indeed
-	 * free this event, otherwise we need to serialize on
+	 * Matches the smp_store_release() in perf_event_exit_task(). If we
+	 * observe !owner it means the list deletion is complete and we can
+	 * indeed free this event, otherwise we need to serialize on
 	 * owner->perf_event_mutex.
 	 */
-	smp_read_barrier_depends();
+	owner = lockless_dereference(event->owner);
 	if (owner) {
 		/*
 		 * Since delayed_put_task_struct() also drops the last
@@ -3737,8 +3728,10 @@
 		 * ensured they're done, and we can proceed with freeing the
 		 * event.
 		 */
-		if (event->owner)
+		if (event->owner) {
 			list_del_init(&event->owner_entry);
+			smp_store_release(&event->owner, NULL);
+		}
 		mutex_unlock(&owner->perf_event_mutex);
 		put_task_struct(owner);
 	}
@@ -3746,36 +3739,98 @@
 
 static void put_event(struct perf_event *event)
 {
-	struct perf_event_context *ctx;
-
 	if (!atomic_long_dec_and_test(&event->refcount))
 		return;
 
-	if (!is_kernel_event(event))
-		perf_remove_from_owner(event);
-
-	/*
-	 * There are two ways this annotation is useful:
-	 *
-	 *  1) there is a lock recursion from perf_event_exit_task
-	 *     see the comment there.
-	 *
-	 *  2) there is a lock-inversion with mmap_sem through
-	 *     perf_read_group(), which takes faults while
-	 *     holding ctx->mutex, however this is called after
-	 *     the last filedesc died, so there is no possibility
-	 *     to trigger the AB-BA case.
-	 */
-	ctx = perf_event_ctx_lock_nested(event, SINGLE_DEPTH_NESTING);
-	WARN_ON_ONCE(ctx->parent_ctx);
-	perf_remove_from_context(event, true);
-	perf_event_ctx_unlock(event, ctx);
-
 	_free_event(event);
 }
 
+/*
+ * Kill an event dead; while event:refcount will preserve the event
+ * object, it will not preserve its functionality. Once the last 'user'
+ * gives up the object, we'll destroy the thing.
+ */
 int perf_event_release_kernel(struct perf_event *event)
 {
+	struct perf_event_context *ctx;
+	struct perf_event *child, *tmp;
+
+	if (!is_kernel_event(event))
+		perf_remove_from_owner(event);
+
+	ctx = perf_event_ctx_lock(event);
+	WARN_ON_ONCE(ctx->parent_ctx);
+	perf_remove_from_context(event, DETACH_GROUP | DETACH_STATE);
+	perf_event_ctx_unlock(event, ctx);
+
+	/*
+	 * At this point we must have event->state == PERF_EVENT_STATE_EXIT,
+	 * either from the above perf_remove_from_context() or through
+	 * perf_event_exit_event().
+	 *
+	 * Therefore, anybody acquiring event->child_mutex after the below
+	 * loop _must_ also see this, most importantly inherit_event() which
+	 * will avoid placing more children on the list.
+	 *
+	 * Thus this guarantees that we will in fact observe and kill _ALL_
+	 * child events.
+	 */
+	WARN_ON_ONCE(event->state != PERF_EVENT_STATE_EXIT);
+
+again:
+	mutex_lock(&event->child_mutex);
+	list_for_each_entry(child, &event->child_list, child_list) {
+
+		/*
+		 * Cannot change, child events are not migrated, see the
+		 * comment with perf_event_ctx_lock_nested().
+		 */
+		ctx = lockless_dereference(child->ctx);
+		/*
+		 * Since child_mutex nests inside ctx::mutex, we must jump
+		 * through hoops. We start by grabbing a reference on the ctx.
+		 *
+		 * Since the event cannot get freed while we hold the
+		 * child_mutex, the context must also exist and have a !0
+		 * reference count.
+		 */
+		get_ctx(ctx);
+
+		/*
+		 * Now that we have a ctx ref, we can drop child_mutex, and
+		 * acquire ctx::mutex without fear of it going away. Then we
+		 * can re-acquire child_mutex.
+		 */
+		mutex_unlock(&event->child_mutex);
+		mutex_lock(&ctx->mutex);
+		mutex_lock(&event->child_mutex);
+
+		/*
+		 * Now that we hold ctx::mutex and child_mutex, revalidate our
+		 * state, if child is still the first entry, it didn't get freed
+		 * and we can continue doing so.
+		 */
+		tmp = list_first_entry_or_null(&event->child_list,
+					       struct perf_event, child_list);
+		if (tmp == child) {
+			perf_remove_from_context(child, DETACH_GROUP);
+			list_del(&child->child_list);
+			free_event(child);
+			/*
+			 * This matches the refcount bump in inherit_event();
+			 * this can't be the last reference.
+			 */
+			put_event(event);
+		}
+
+		mutex_unlock(&event->child_mutex);
+		mutex_unlock(&ctx->mutex);
+		put_ctx(ctx);
+		goto again;
+	}
+	mutex_unlock(&event->child_mutex);
+
+	/* Must be the last reference */
 	put_event(event);
 	return 0;
 }
@@ -3786,46 +3841,10 @@
  */
 static int perf_release(struct inode *inode, struct file *file)
 {
-	put_event(file->private_data);
+	perf_event_release_kernel(file->private_data);
 	return 0;
 }
 
-/*
- * Remove all orphanes events from the context.
- */
-static void orphans_remove_work(struct work_struct *work)
-{
-	struct perf_event_context *ctx;
-	struct perf_event *event, *tmp;
-
-	ctx = container_of(work, struct perf_event_context,
-			   orphans_remove.work);
-
-	mutex_lock(&ctx->mutex);
-	list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry) {
-		struct perf_event *parent_event = event->parent;
-
-		if (!is_orphaned_child(event))
-			continue;
-
-		perf_remove_from_context(event, true);
-
-		mutex_lock(&parent_event->child_mutex);
-		list_del_init(&event->child_list);
-		mutex_unlock(&parent_event->child_mutex);
-
-		free_event(event);
-		put_event(parent_event);
-	}
-
-	raw_spin_lock_irq(&ctx->lock);
-	ctx->orphans_remove_sched = false;
-	raw_spin_unlock_irq(&ctx->lock);
-	mutex_unlock(&ctx->mutex);
-
-	put_ctx(ctx);
-}
-
 u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 {
 	struct perf_event *child;
@@ -4054,7 +4073,7 @@
 /*
  * Holding the top-level event's child_mutex means that any
  * descendant process that has inherited this event will block
- * in sync_child_event if it goes to exit, thus satisfying the
+ * in perf_event_exit_event() if it goes to exit, thus satisfying the
  * task existence requirements of perf_event_enable/disable.
  */
 static void perf_event_for_each_child(struct perf_event *event,
@@ -4086,36 +4105,14 @@
 		perf_event_for_each_child(sibling, func);
 }
 
-struct period_event {
-	struct perf_event *event;
-	u64 value;
-};
-
-static void ___perf_event_period(void *info)
+static void __perf_event_period(struct perf_event *event,
+				struct perf_cpu_context *cpuctx,
+				struct perf_event_context *ctx,
+				void *info)
 {
-	struct period_event *pe = info;
-	struct perf_event *event = pe->event;
-	u64 value = pe->value;
-
-	if (event->attr.freq) {
-		event->attr.sample_freq = value;
-	} else {
-		event->attr.sample_period = value;
-		event->hw.sample_period = value;
-	}
-
-	local64_set(&event->hw.period_left, 0);
-}
-
-static int __perf_event_period(void *info)
-{
-	struct period_event *pe = info;
-	struct perf_event *event = pe->event;
-	struct perf_event_context *ctx = event->ctx;
-	u64 value = pe->value;
+	u64 value = *((u64 *)info);
 	bool active;
 
-	raw_spin_lock(&ctx->lock);
 	if (event->attr.freq) {
 		event->attr.sample_freq = value;
 	} else {
@@ -4135,14 +4132,10 @@
 		event->pmu->start(event, PERF_EF_RELOAD);
 		perf_pmu_enable(ctx->pmu);
 	}
-	raw_spin_unlock(&ctx->lock);
-
-	return 0;
 }
 
 static int perf_event_period(struct perf_event *event, u64 __user *arg)
 {
-	struct period_event pe = { .event = event, };
 	u64 value;
 
 	if (!is_sampling_event(event))
@@ -4157,10 +4150,7 @@
 	if (event->attr.freq && value > sysctl_perf_event_sample_rate)
 		return -EINVAL;
 
-	pe.value = value;
-
-	event_function_call(event, __perf_event_period,
-			    ___perf_event_period, &pe);
+	event_function_call(event, __perf_event_period, &value);
 
 	return 0;
 }
@@ -4932,7 +4922,7 @@
 
 	if (event->pending_disable) {
 		event->pending_disable = 0;
-		__perf_event_disable(event);
+		perf_event_disable_local(event);
 	}
 
 	if (event->pending_wakeup) {
@@ -7753,11 +7743,13 @@
 
 static void account_event(struct perf_event *event)
 {
+	bool inc = false;
+
 	if (event->parent)
 		return;
 
 	if (event->attach_state & PERF_ATTACH_TASK)
-		static_key_slow_inc(&perf_sched_events.key);
+		inc = true;
 	if (event->attr.mmap || event->attr.mmap_data)
 		atomic_inc(&nr_mmap_events);
 	if (event->attr.comm)
@@ -7770,11 +7762,14 @@
 	}
 	if (event->attr.context_switch) {
 		atomic_inc(&nr_switch_events);
-		static_key_slow_inc(&perf_sched_events.key);
+		inc = true;
 	}
 	if (has_branch_stack(event))
-		static_key_slow_inc(&perf_sched_events.key);
+		inc = true;
 	if (is_cgroup_event(event))
+		inc = true;
+
+	if (inc)
 		static_key_slow_inc(&perf_sched_events.key);
 
 	account_event_cpu(event, event->cpu);
@@ -8422,11 +8417,11 @@
 		 * See perf_event_ctx_lock() for comments on the details
 		 * of swizzling perf_event::ctx.
 		 */
-		perf_remove_from_context(group_leader, false);
+		perf_remove_from_context(group_leader, 0);
 
 		list_for_each_entry(sibling, &group_leader->sibling_list,
 				    group_entry) {
-			perf_remove_from_context(sibling, false);
+			perf_remove_from_context(sibling, 0);
 			put_ctx(gctx);
 		}
 
@@ -8479,6 +8474,8 @@
 	perf_event__header_size(event);
 	perf_event__id_header_size(event);
 
+	event->owner = current;
+
 	perf_install_in_context(ctx, event, event->cpu);
 	perf_unpin_context(ctx);
 
@@ -8488,8 +8485,6 @@
 
 	put_online_cpus();
 
-	event->owner = current;
-
 	mutex_lock(&current->perf_event_mutex);
 	list_add_tail(&event->owner_entry, &current->perf_event_list);
 	mutex_unlock(&current->perf_event_mutex);
@@ -8556,7 +8551,7 @@
 	}
 
 	/* Mark owner so we could distinguish it from user events. */
-	event->owner = EVENT_OWNER_KERNEL;
+	event->owner = TASK_TOMBSTONE;
 
 	account_event(event);
 
@@ -8606,7 +8601,7 @@
 	mutex_lock_double(&src_ctx->mutex, &dst_ctx->mutex);
 	list_for_each_entry_safe(event, tmp, &src_ctx->event_list,
 				 event_entry) {
-		perf_remove_from_context(event, false);
+		perf_remove_from_context(event, 0);
 		unaccount_event_cpu(event, src_cpu);
 		put_ctx(src_ctx);
 		list_add(&event->migrate_entry, &events);
@@ -8673,33 +8668,15 @@
 		     &parent_event->child_total_time_enabled);
 	atomic64_add(child_event->total_time_running,
 		     &parent_event->child_total_time_running);
-
-	/*
-	 * Remove this event from the parent's list
-	 */
-	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
-	mutex_lock(&parent_event->child_mutex);
-	list_del_init(&child_event->child_list);
-	mutex_unlock(&parent_event->child_mutex);
-
-	/*
-	 * Make sure user/parent get notified, that we just
-	 * lost one event.
-	 */
-	perf_event_wakeup(parent_event);
-
-	/*
-	 * Release the parent event, if this was the last
-	 * reference to it.
-	 */
-	put_event(parent_event);
 }
 
 static void
-__perf_event_exit_task(struct perf_event *child_event,
-			 struct perf_event_context *child_ctx,
-			 struct task_struct *child)
+perf_event_exit_event(struct perf_event *child_event,
+		      struct perf_event_context *child_ctx,
+		      struct task_struct *child)
 {
+	struct perf_event *parent_event = child_event->parent;
+
 	/*
 	 * Do not destroy the 'original' grouping; because of the context
 	 * switch optimization the original events could've ended up in a
@@ -8712,57 +8689,86 @@
 	 * Do destroy all inherited groups, we don't care about those
 	 * and being thorough is better.
 	 */
-	perf_remove_from_context(child_event, !!child_event->parent);
+	raw_spin_lock_irq(&child_ctx->lock);
+	WARN_ON_ONCE(child_ctx->is_active);
+
+	if (parent_event)
+		perf_group_detach(child_event);
+	list_del_event(child_event, child_ctx);
+	child_event->state = PERF_EVENT_STATE_EXIT; /* see perf_event_release_kernel() */
+	raw_spin_unlock_irq(&child_ctx->lock);
 
 	/*
-	 * It can happen that the parent exits first, and has events
-	 * that are still around due to the child reference. These
-	 * events need to be zapped.
+	 * Parent events are governed by their filedesc, retain them.
 	 */
-	if (child_event->parent) {
-		sync_child_event(child_event, child);
-		free_event(child_event);
-	} else {
-		child_event->state = PERF_EVENT_STATE_EXIT;
+	if (!parent_event) {
 		perf_event_wakeup(child_event);
+		return;
 	}
+	/*
+	 * Child events can be cleaned up.
+	 */
+
+	sync_child_event(child_event, child);
+
+	/*
+	 * Remove this event from the parent's list
+	 */
+	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
+	mutex_lock(&parent_event->child_mutex);
+	list_del_init(&child_event->child_list);
+	mutex_unlock(&parent_event->child_mutex);
+
+	/*
+	 * Kick perf_poll() for is_event_hup().
+	 */
+	perf_event_wakeup(parent_event);
+	free_event(child_event);
+	put_event(parent_event);
 }
 
 static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
 {
-	struct perf_event *child_event, *next;
 	struct perf_event_context *child_ctx, *clone_ctx = NULL;
-	unsigned long flags;
+	struct perf_event *child_event, *next;
 
-	if (likely(!child->perf_event_ctxp[ctxn]))
+	WARN_ON_ONCE(child != current);
+
+	child_ctx = perf_pin_task_context(child, ctxn);
+	if (!child_ctx)
 		return;
 
-	local_irq_save(flags);
 	/*
-	 * We can't reschedule here because interrupts are disabled,
-	 * and either child is current or it is a task that can't be
-	 * scheduled, so we are now safe from rescheduling changing
-	 * our context.
+	 * In order to reduce the amount of tricky in ctx tear-down, we hold
+	 * ctx::mutex over the entire thing. This serializes against almost
+	 * everything that wants to access the ctx.
+	 *
+	 * The exception is sys_perf_event_open() /
+	 * perf_event_create_kernel_count() which does find_get_context()
+	 * without ctx::mutex (it cannot because of the move_group double mutex
+	 * lock thing). See the comments in perf_install_in_context().
 	 */
-	child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
+	mutex_lock(&child_ctx->mutex);
 
 	/*
-	 * Take the context lock here so that if find_get_context is
-	 * reading child->perf_event_ctxp, we wait until it has
-	 * incremented the context's refcount before we do put_ctx below.
+	 * In a single ctx::lock section, de-schedule the events and detach the
+	 * context from the task such that we cannot ever get it scheduled back
+	 * in.
 	 */
-	raw_spin_lock(&child_ctx->lock);
-	task_ctx_sched_out(child_ctx);
-	child->perf_event_ctxp[ctxn] = NULL;
+	raw_spin_lock_irq(&child_ctx->lock);
+	task_ctx_sched_out(__get_cpu_context(child_ctx), child_ctx);
 
 	/*
-	 * If this context is a clone; unclone it so it can't get
-	 * swapped to another process while we're removing all
-	 * the events from it.
+	 * Now that the context is inactive, destroy the task <-> ctx relation
+	 * and mark the context dead.
 	 */
+	RCU_INIT_POINTER(child->perf_event_ctxp[ctxn], NULL);
+	put_ctx(child_ctx); /* cannot be last */
+	WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
+	put_task_struct(current); /* cannot be last */
+
 	clone_ctx = unclone_ctx(child_ctx);
-	update_context_time(child_ctx);
-	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+	raw_spin_unlock_irq(&child_ctx->lock);
 
 	if (clone_ctx)
 		put_ctx(clone_ctx);
@@ -8774,20 +8780,8 @@
 	 */
 	perf_event_task(child, child_ctx, 0);
 
-	/*
-	 * We can recurse on the same lock type through:
-	 *
-	 *   __perf_event_exit_task()
-	 *     sync_child_event()
-	 *       put_event()
-	 *         mutex_lock(&ctx->mutex)
-	 *
-	 * But since its the parent context it won't be the same instance.
-	 */
-	mutex_lock(&child_ctx->mutex);
-
 	list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry)
-		__perf_event_exit_task(child_event, child_ctx, child);
+		perf_event_exit_event(child_event, child_ctx, child);
 
 	mutex_unlock(&child_ctx->mutex);
 
@@ -8812,8 +8806,7 @@
 		 * the owner, closes a race against perf_release() where
 		 * we need to serialize on the owner->perf_event_mutex.
 		 */
-		smp_wmb();
-		event->owner = NULL;
+		smp_store_release(&event->owner, NULL);
 	}
 	mutex_unlock(&child->perf_event_mutex);
 
@@ -8896,21 +8889,20 @@
 		WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
 }
 
-struct perf_event *perf_event_get(unsigned int fd)
+struct file *perf_event_get(unsigned int fd)
 {
-	int err;
-	struct fd f;
-	struct perf_event *event;
+	struct file *file;
 
-	err = perf_fget_light(fd, &f);
-	if (err)
-		return ERR_PTR(err);
+	file = fget_raw(fd);
+	if (!file)
+		return ERR_PTR(-EBADF);
 
-	event = f.file->private_data;
-	atomic_long_inc(&event->refcount);
-	fdput(f);
+	if (file->f_op != &perf_fops) {
+		fput(file);
+		return ERR_PTR(-EBADF);
+	}
 
-	return event;
+	return file;
 }
 
 const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
@@ -8953,8 +8945,16 @@
 	if (IS_ERR(child_event))
 		return child_event;
 
+	/*
+	 * is_orphaned_event() and list_add_tail(&parent_event->child_list)
+	 * must be under the same lock in order to serialize against
+	 * perf_event_release_kernel(), such that either we must observe
+	 * is_orphaned_event() or they will observe us on the child_list.
+	 */
+	mutex_lock(&parent_event->child_mutex);
 	if (is_orphaned_event(parent_event) ||
 	    !atomic_long_inc_not_zero(&parent_event->refcount)) {
+		mutex_unlock(&parent_event->child_mutex);
 		free_event(child_event);
 		return NULL;
 	}
@@ -9002,8 +9002,6 @@
 	/*
 	 * Link this into the parent event's child list
 	 */
-	WARN_ON_ONCE(parent_event->ctx->parent_ctx);
-	mutex_lock(&parent_event->child_mutex);
 	list_add_tail(&child_event->child_list, &parent_event->child_list);
 	mutex_unlock(&parent_event->child_mutex);
 
@@ -9221,13 +9219,14 @@
 #if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
 static void __perf_event_exit_context(void *__info)
 {
-	struct remove_event re = { .detach_group = true };
 	struct perf_event_context *ctx = __info;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event *event;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(re.event, &ctx->event_list, event_entry)
-		__perf_remove_from_context(&re);
-	rcu_read_unlock();
+	raw_spin_lock(&ctx->lock);
+	list_for_each_entry(event, &ctx->event_list, event_entry)
+		__perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
+	raw_spin_unlock(&ctx->lock);
 }
 
 static void perf_event_exit_cpu_context(int cpu)
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 92ce5f4..3f8cb1e 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -444,7 +444,7 @@
 	 * current task.
 	 */
 	if (irqs_disabled() && bp->ctx && bp->ctx->task == current)
-		__perf_event_disable(bp);
+		perf_event_disable_local(bp);
 	else
 		perf_event_disable(bp);
 
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index adfdc05..1faad2cf 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -459,6 +459,25 @@
 	__free_page(page);
 }
 
+static void __rb_free_aux(struct ring_buffer *rb)
+{
+	int pg;
+
+	if (rb->aux_priv) {
+		rb->free_aux(rb->aux_priv);
+		rb->free_aux = NULL;
+		rb->aux_priv = NULL;
+	}
+
+	if (rb->aux_nr_pages) {
+		for (pg = 0; pg < rb->aux_nr_pages; pg++)
+			rb_free_aux_page(rb, pg);
+
+		kfree(rb->aux_pages);
+		rb->aux_nr_pages = 0;
+	}
+}
+
 int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
 		 pgoff_t pgoff, int nr_pages, long watermark, int flags)
 {
@@ -547,30 +566,11 @@
 	if (!ret)
 		rb->aux_pgoff = pgoff;
 	else
-		rb_free_aux(rb);
+		__rb_free_aux(rb);
 
 	return ret;
 }
 
-static void __rb_free_aux(struct ring_buffer *rb)
-{
-	int pg;
-
-	if (rb->aux_priv) {
-		rb->free_aux(rb->aux_priv);
-		rb->free_aux = NULL;
-		rb->aux_priv = NULL;
-	}
-
-	if (rb->aux_nr_pages) {
-		for (pg = 0; pg < rb->aux_nr_pages; pg++)
-			rb_free_aux_page(rb, pg);
-
-		kfree(rb->aux_pages);
-		rb->aux_nr_pages = 0;
-	}
-}
-
 void rb_free_aux(struct ring_buffer *rb)
 {
 	if (atomic_dec_and_test(&rb->aux_refcount))
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 45dd798..326a75e 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -191,14 +191,17 @@
 	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	struct perf_event *event;
+	struct file *file;
 
 	if (unlikely(index >= array->map.max_entries))
 		return -E2BIG;
 
-	event = (struct perf_event *)array->ptrs[index];
-	if (!event)
+	file = (struct file *)array->ptrs[index];
+	if (unlikely(!file))
 		return -ENOENT;
 
+	event = file->private_data;
+
 	/* make sure event is local and doesn't have pmu::count */
 	if (event->oncpu != smp_processor_id() ||
 	    event->pmu->count)
@@ -228,6 +231,7 @@
 	void *data = (void *) (long) r4;
 	struct perf_sample_data sample_data;
 	struct perf_event *event;
+	struct file *file;
 	struct perf_raw_record raw = {
 		.size = size,
 		.data = data,
@@ -236,10 +240,12 @@
 	if (unlikely(index >= array->map.max_entries))
 		return -E2BIG;
 
-	event = (struct perf_event *)array->ptrs[index];
-	if (unlikely(!event))
+	file = (struct file *)array->ptrs[index];
+	if (unlikely(!file))
 		return -ENOENT;
 
+	event = file->private_data;
+
 	if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
 		     event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
 		return -EINVAL;
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 0a22407..5d34815 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -77,6 +77,9 @@
 # Define NO_AUXTRACE if you do not want AUX area tracing support
 #
 # Define NO_LIBBPF if you do not want BPF support
+#
+# Define FEATURES_DUMP to provide features detection dump file
+# and bypass the feature detection
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
@@ -166,6 +169,15 @@
 include config/Makefile
 endif
 
+# The FEATURE_DUMP_EXPORT holds location of the actual
+# FEATURE_DUMP file to be used to bypass feature detection
+# (for bpf or any other subproject)
+ifeq ($(FEATURES_DUMP),)
+FEATURE_DUMP_EXPORT := $(realpath $(OUTPUT)FEATURE-DUMP)
+else
+FEATURE_DUMP_EXPORT := $(FEATURES_DUMP)
+endif
+
 export prefix bindir sharedir sysconfdir DESTDIR
 
 # sparse is architecture-neutral, which means that we need to tell it
@@ -436,7 +448,7 @@
 	$(Q)$(MAKE) -C $(LIB_DIR) O=$(OUTPUT) clean >/dev/null
 
 $(LIBBPF): fixdep FORCE
-	$(Q)$(MAKE) -C $(BPF_DIR) O=$(OUTPUT) $(OUTPUT)libbpf.a FEATURES_DUMP=$(realpath $(OUTPUT)FEATURE-DUMP)
+	$(Q)$(MAKE) -C $(BPF_DIR) O=$(OUTPUT) $(OUTPUT)libbpf.a FEATURES_DUMP=$(FEATURE_DUMP_EXPORT)
 
 $(LIBBPF)-clean:
 	$(call QUIET_CLEAN, libbpf)
@@ -611,6 +623,17 @@
 	$(python-clean)
 
 #
+# To provide FEATURE-DUMP into $(FEATURE_DUMP_COPY)
+# file if defined, with no further action.
+feature-dump:
+ifdef FEATURE_DUMP_COPY
+	@cp $(OUTPUT)FEATURE-DUMP $(FEATURE_DUMP_COPY)
+	@echo "FEATURE-DUMP file copied into $(FEATURE_DUMP_COPY)"
+else
+	@echo "FEATURE-DUMP file available in $(OUTPUT)FEATURE-DUMP"
+endif
+
+#
 # Trick: if ../../.git does not exist - we are building out of tree for example,
 # then force version regeneration:
 #
diff --git a/tools/perf/arch/x86/tests/intel-cqm.c b/tools/perf/arch/x86/tests/intel-cqm.c
index 3e89ba8..7f064eb 100644
--- a/tools/perf/arch/x86/tests/intel-cqm.c
+++ b/tools/perf/arch/x86/tests/intel-cqm.c
@@ -17,7 +17,7 @@
 	if (pid)
 		return pid;
 
-	while(1);
+	while(1)
 		sleep(5);
 	return 0;
 }
diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index e5959c1..511141b 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -181,7 +181,11 @@
 
 EXTLIBS = -lpthread -lrt -lm -ldl
 
+ifeq ($(FEATURES_DUMP),)
 include $(srctree)/tools/build/Makefile.feature
+else
+include $(FEATURES_DUMP)
+endif
 
 ifeq ($(feature-stackprotector-all), 1)
   CFLAGS += -fstack-protector-all
diff --git a/tools/perf/tests/make b/tools/perf/tests/make
index df38dec..f918015 100644
--- a/tools/perf/tests/make
+++ b/tools/perf/tests/make
@@ -5,7 +5,7 @@
 # no target specified, trigger the whole suite
 all:
 	@echo "Testing Makefile";      $(MAKE) -sf tests/make MK=Makefile
-	@echo "Testing Makefile.perf"; $(MAKE) -sf tests/make MK=Makefile.perf
+	@echo "Testing Makefile.perf"; $(MAKE) -sf tests/make MK=Makefile.perf SET_PARALLEL=1 SET_O=1
 else
 # run only specific test over 'Makefile'
 %:
@@ -13,6 +13,26 @@
 endif
 else
 PERF := .
+PERF_O := $(PERF)
+O_OPT :=
+
+ifneq ($(O),)
+  FULL_O := $(shell readlink -f $(O) || echo $(O))
+  PERF_O := $(FULL_O)
+  ifeq ($(SET_O),1)
+    O_OPT := 'O=$(FULL_O)'
+  endif
+  K_O_OPT := 'O=$(FULL_O)'
+endif
+
+PARALLEL_OPT=
+ifeq ($(SET_PARALLEL),1)
+  cores := $(shell (getconf _NPROCESSORS_ONLN || egrep -c '^processor|^CPU[0-9]' /proc/cpuinfo) 2>/dev/null)
+  ifeq ($(cores),0)
+    cores := 1
+  endif
+  PARALLEL_OPT="-j$(cores)"
+endif
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
@@ -156,11 +176,11 @@
 test_make_help_O := $(test_ok)
 test_make_doc_O  := $(test_ok)
 
-test_make_python_perf_so := test -f $(PERF)/python/perf.so
+test_make_python_perf_so := test -f $(PERF_O)/python/perf.so
 
-test_make_perf_o           := test -f $(PERF)/perf.o
-test_make_util_map_o       := test -f $(PERF)/util/map.o
-test_make_util_pmu_bison_o := test -f $(PERF)/util/pmu-bison.o
+test_make_perf_o           := test -f $(PERF_O)/perf.o
+test_make_util_map_o       := test -f $(PERF_O)/util/map.o
+test_make_util_pmu_bison_o := test -f $(PERF_O)/util/pmu-bison.o
 
 define test_dest_files
   for file in $(1); do				\
@@ -227,7 +247,7 @@
 test_make_util_map_o_O        := test -f $$TMP_O/util/map.o
 test_make_util_pmu_bison_o_O := test -f $$TMP_O/util/pmu-bison.o
 
-test_default = test -x $(PERF)/perf
+test_default = test -x $(PERF_O)/perf
 test = $(if $(test_$1),$(test_$1),$(test_default))
 
 test_default_O = test -x $$TMP_O/perf
@@ -247,12 +267,12 @@
 
 MAKEFLAGS := --no-print-directory
 
-clean := @(cd $(PERF); make -s -f $(MK) clean >/dev/null)
+clean := @(cd $(PERF); make -s -f $(MK) $(O_OPT) clean >/dev/null)
 
 $(run):
 	$(call clean)
 	@TMP_DEST=$$(mktemp -d); \
-	cmd="cd $(PERF) && make -f $(MK) DESTDIR=$$TMP_DEST $($@)"; \
+	cmd="cd $(PERF) && make -f $(MK) $(PARALLEL_OPT) $(O_OPT) DESTDIR=$$TMP_DEST $($@)"; \
 	echo "- $@: $$cmd" && echo $$cmd > $@ && \
 	( eval $$cmd ) >> $@ 2>&1; \
 	echo "  test: $(call test,$@)" >> $@ 2>&1; \
@@ -263,7 +283,7 @@
 	$(call clean)
 	@TMP_O=$$(mktemp -d); \
 	TMP_DEST=$$(mktemp -d); \
-	cmd="cd $(PERF) && make -f $(MK) O=$$TMP_O DESTDIR=$$TMP_DEST $($(patsubst %_O,%,$@))"; \
+	cmd="cd $(PERF) && make -f $(MK) $(PARALLEL_OPT) O=$$TMP_O DESTDIR=$$TMP_DEST $($(patsubst %_O,%,$@))"; \
 	echo "- $@: $$cmd" && echo $$cmd > $@ && \
 	( eval $$cmd ) >> $@ 2>&1 && \
 	echo "  test: $(call test_O,$@)" >> $@ 2>&1; \
@@ -276,17 +296,22 @@
 	( eval $$cmd ) >> $@ 2>&1 && \
 	rm -f $@
 
+KERNEL_O := ../..
+ifneq ($(O),)
+  KERNEL_O := $(O)
+endif
+
 make_kernelsrc:
-	@echo "- make -C <kernelsrc> tools/perf"
+	@echo "- make -C <kernelsrc> $(PARALLEL_OPT) $(K_O_OPT) tools/perf"
 	$(call clean); \
-	(make -C ../.. tools/perf) > $@ 2>&1 && \
-	test -x perf && rm -f $@ || (cat $@ ; false)
+	(make -C ../.. $(PARALLEL_OPT) $(K_O_OPT) tools/perf) > $@ 2>&1 && \
+	test -x $(KERNEL_O)/tools/perf/perf && rm -f $@ || (cat $@ ; false)
 
 make_kernelsrc_tools:
-	@echo "- make -C <kernelsrc>/tools perf"
+	@echo "- make -C <kernelsrc>/tools $(PARALLEL_OPT) $(K_O_OPT) perf"
 	$(call clean); \
-	(make -C ../../tools perf) > $@ 2>&1 && \
-	test -x perf && rm -f $@ || (cat $@ ; false)
+	(make -C ../../tools $(PARALLEL_OPT) $(K_O_OPT) perf) > $@ 2>&1 && \
+	test -x $(KERNEL_O)/tools/perf/perf && rm -f $@ || (cat $@ ; false)
 
 all: $(run) $(run_O) tarpkg make_kernelsrc make_kernelsrc_tools
 	@echo OK
diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index d4d7cc2..718bd46 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -755,11 +755,11 @@
 				nd = browser->curr_hot;
 			break;
 		case K_UNTAB:
-			if (nd != NULL)
+			if (nd != NULL) {
 				nd = rb_next(nd);
 				if (nd == NULL)
 					nd = rb_first(&browser->entries);
-			else
+			} else
 				nd = browser->curr_hot;
 			break;
 		case K_F1:
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index c226303..68a7612 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -131,6 +131,8 @@
 			symlen = unresolved_col_width + 4 + 2;
 			hists__new_col_len(hists, HISTC_MEM_DADDR_SYMBOL,
 					   symlen);
+			hists__new_col_len(hists, HISTC_MEM_DCACHELINE,
+					   symlen);
 		}
 
 		if (h->mem_info->iaddr.sym) {
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index d5636ba..40b7a0d 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1149,7 +1149,7 @@
 
 		machine = machines__find(machines, pid);
 		if (!machine)
-			machine = machines__find(machines, DEFAULT_GUEST_KERNEL_ID);
+			machine = machines__findnew(machines, DEFAULT_GUEST_KERNEL_ID);
 		return machine;
 	}
 
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 2f901d1..2b58edc 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -310,7 +310,6 @@
 	int i, ret;
 
 	aggr->val = aggr->ena = aggr->run = 0;
-	init_stats(ps->res_stats);
 
 	if (counter->per_pkg)
 		zero_per_pkg(counter);
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 3b2de6e..ab02209 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1466,7 +1466,7 @@
 	 * Read the build id if possible. This is required for
 	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
 	 */
-	if (filename__read_build_id(dso->name, build_id, BUILD_ID_SIZE) > 0)
+	if (filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0)
 		dso__set_build_id(dso, build_id);
 
 	/*