diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index e8b6af1..9293ce5 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -656,14 +656,11 @@ static int amd_uncore_df_event_init(struct perf_event *event)
 	struct hw_perf_event *hwc = &event->hw;
 	int ret = amd_uncore_event_init(event);
 
-	if (ret || pmu_version < 2)
-		return ret;
-
 	hwc->config = event->attr.config &
 		      (pmu_version >= 2 ? AMD64_PERFMON_V2_RAW_EVENT_MASK_NB :
 					  AMD64_RAW_EVENT_MASK_NB);
 
-	return 0;
+	return ret;
 }
 
 static int amd_uncore_df_add(struct perf_event *event, int flags)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 853fe07..bdf3f0d 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3378,6 +3378,9 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 
 		if (!test_bit(bit, cpuc->active_mask))
 			continue;
+		/* Event may have already been cleared: */
+		if (!event)
+			continue;
 
 		/*
 		 * There may be unprocessed PEBS records in the PEBS buffer,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ece7168..dad0d3d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2317,8 +2317,6 @@ out:
 	perf_event__header_size(leader);
 }
 
-static void sync_child_event(struct perf_event *child_event);
-
 static void perf_child_detach(struct perf_event *event)
 {
 	struct perf_event *parent_event = event->parent;
@@ -2337,7 +2335,6 @@ static void perf_child_detach(struct perf_event *event)
 	lockdep_assert_held(&parent_event->child_mutex);
 	 */
 
-	sync_child_event(event);
 	list_del_init(&event->child_list);
 }
 
@@ -4588,6 +4585,7 @@ out:
 static void perf_remove_from_owner(struct perf_event *event);
 static void perf_event_exit_event(struct perf_event *event,
 				  struct perf_event_context *ctx,
+				  struct task_struct *task,
 				  bool revoke);
 
 /*
@@ -4615,7 +4613,7 @@ static void perf_event_remove_on_exec(struct perf_event_context *ctx)
 
 		modified = true;
 
-		perf_event_exit_event(event, ctx, false);
+		perf_event_exit_event(event, ctx, ctx->task, false);
 	}
 
 	raw_spin_lock_irqsave(&ctx->lock, flags);
@@ -12518,7 +12516,7 @@ static void __pmu_detach_event(struct pmu *pmu, struct perf_event *event,
 	/*
 	 * De-schedule the event and mark it REVOKED.
 	 */
-	perf_event_exit_event(event, ctx, true);
+	perf_event_exit_event(event, ctx, ctx->task, true);
 
 	/*
 	 * All _free_event() bits that rely on event->pmu:
@@ -14075,14 +14073,13 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
 }
 EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
 
-static void sync_child_event(struct perf_event *child_event)
+static void sync_child_event(struct perf_event *child_event,
+			     struct task_struct *task)
 {
 	struct perf_event *parent_event = child_event->parent;
 	u64 child_val;
 
 	if (child_event->attr.inherit_stat) {
-		struct task_struct *task = child_event->ctx->task;
-
 		if (task && task != TASK_TOMBSTONE)
 			perf_event_read_event(child_event, task);
 	}
@@ -14101,7 +14098,9 @@ static void sync_child_event(struct perf_event *child_event)
 
 static void
 perf_event_exit_event(struct perf_event *event,
-		      struct perf_event_context *ctx, bool revoke)
+		      struct perf_event_context *ctx,
+		      struct task_struct *task,
+		      bool revoke)
 {
 	struct perf_event *parent_event = event->parent;
 	unsigned long detach_flags = DETACH_EXIT;
@@ -14124,6 +14123,9 @@ perf_event_exit_event(struct perf_event *event,
 		mutex_lock(&parent_event->child_mutex);
 		/* PERF_ATTACH_ITRACE might be set concurrently */
 		attach_state = READ_ONCE(event->attach_state);
+
+		if (attach_state & PERF_ATTACH_CHILD)
+			sync_child_event(event, task);
 	}
 
 	if (revoke)
@@ -14215,7 +14217,7 @@ static void perf_event_exit_task_context(struct task_struct *task, bool exit)
 		perf_event_task(task, ctx, 0);
 
 	list_for_each_entry_safe(child_event, next, &ctx->event_list, event_entry)
-		perf_event_exit_event(child_event, ctx, false);
+		perf_event_exit_event(child_event, ctx, exit ? task : NULL, false);
 
 	mutex_unlock(&ctx->mutex);
 
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f11ceb8..d546d32 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -79,7 +79,7 @@ struct uprobe {
 	 * The generic code assumes that it has two members of unknown type
 	 * owned by the arch-specific code:
 	 *
-	 * 	insn -	copy_insn() saves the original instruction here for
+	 *	insn -	copy_insn() saves the original instruction here for
 	 *		arch_uprobe_analyze_insn().
 	 *
 	 *	ixol -	potentially modified instruction to execute out of
@@ -107,8 +107,8 @@ static LIST_HEAD(delayed_uprobe_list);
  * allocated.
  */
 struct xol_area {
-	wait_queue_head_t 		wq;		/* if all slots are busy */
-	unsigned long 			*bitmap;	/* 0 = free slot */
+	wait_queue_head_t		wq;		/* if all slots are busy */
+	unsigned long			*bitmap;	/* 0 = free slot */
 
 	struct page			*page;
 	/*
@@ -116,7 +116,7 @@ struct xol_area {
 	 * itself.  The probed process or a naughty kernel module could make
 	 * the vma go away, and we must handle that reasonably gracefully.
 	 */
-	unsigned long 			vaddr;		/* Page(s) of instruction slots */
+	unsigned long			vaddr;		/* Page(s) of instruction slots */
 };
 
 static void uprobe_warn(struct task_struct *t, const char *msg)