Merge branch 'perf/urgent' into perf/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

20 files changed, 148 insertions, 66 deletions

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index f378613ad120..f215990b9061 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -613,6 +613,16 @@ static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops
 			continue;
 
 		data_size = fp->entry_data_size;
+		/*
+		 * The list may have grown since it was sized, so this node
+		 * may not fit. Skip it as missed rather than overrun the
+		 * reservation.
+		 */
+		if (fp->exit_handler &&
+		    used + FPROBE_HEADER_SIZE_IN_LONG + SIZE_IN_LONG(data_size) > reserved_words) {
+			fp->nmissed++;
+			continue;
+		}
 		if (data_size && fp->exit_handler)
 			data = fgraph_data + used + FPROBE_HEADER_SIZE_IN_LONG;
 		else
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f93e34dd2328..6c47a94f5924 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1098,6 +1098,12 @@ struct ftrace_ops global_ops = {
 };
 
 /*
+ * parser_lock - Protects trace_parser state against concurrent operations.
+ * Held across trace_get_user() and subsequent buffer parsing to prevent races.
+ */
+static DEFINE_MUTEX(parser_lock);
+
+/*
  * Used by the stack unwinder to know about dynamic ftrace trampolines.
  */
 struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)
@@ -5842,6 +5848,8 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
 	/* iter->hash is a local copy, so we don't need regex_lock */
 
 	parser = &iter->parser;
+
+	guard(mutex)(&parser_lock);
 	read = trace_get_user(parser, ubuf, cnt, ppos);
 
 	if (read >= 0 && trace_parser_loaded(parser) &&
@@ -6984,12 +6992,14 @@ int ftrace_regex_release(struct inode *inode, struct file *file)
 		iter = file->private_data;
 
 	parser = &iter->parser;
+	mutex_lock(&parser_lock);
 	if (trace_parser_loaded(parser)) {
 		int enable = !(iter->flags & FTRACE_ITER_NOTRACE);
 
 		ftrace_process_regex(iter, parser->buffer,
 				     parser->idx, enable);
 	}
+	mutex_unlock(&parser_lock);
 
 	trace_parser_put(parser);
 
@@ -7321,10 +7331,12 @@ ftrace_graph_release(struct inode *inode, struct file *file)
 
 		parser = &fgd->parser;
 
+		mutex_lock(&parser_lock);
 		if (trace_parser_loaded((parser))) {
 			ret = ftrace_graph_set_hash(fgd->new_hash,
 						    parser->buffer);
 		}
+		mutex_unlock(&parser_lock);
 
 		trace_parser_put(parser);
 
@@ -7437,6 +7449,7 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
 
 	parser = &fgd->parser;
 
+	guard(mutex)(&parser_lock);
 	read = trace_get_user(parser, ubuf, cnt, ppos);
 
 	if (read >= 0 && trace_parser_loaded(parser) &&
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 56a328e94395..804ccae694d2 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -270,7 +270,8 @@ unsigned ring_buffer_event_length(struct ring_buffer_event *event)
 	if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
 		return length;
 	length -= RB_EVNT_HDR_SIZE;
-	if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0]))
+	if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0]) ||
+	    RB_FORCE_8BYTE_ALIGNMENT)
                 length -= sizeof(event->array[0]);
 	return length;
 }
@@ -2329,10 +2330,7 @@ static struct ring_buffer_desc *ring_buffer_desc(struct trace_buffer_desc *trace
 	size_t len;
 	int i;
 
-	if (!trace_desc)
-		return NULL;
-
-	if (cpu >= trace_desc->nr_cpus)
+	if (!trace_desc || !trace_desc->nr_cpus)
 		return NULL;
 
 	end = (struct ring_buffer_desc *)((void *)trace_desc + trace_desc->struct_len);
@@ -7174,7 +7172,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer,
 			rpos = reader->read;
 			pos += event_size;
 
-			if (rpos >= event_size)
+			if (rpos >= size)
 				break;
 
 			event = rb_reader_event(cpu_buffer);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1146b83b711a..01a5e87af299 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -87,7 +87,7 @@ void __init disable_tracing_selftest(const char *reason)
 
 /* Pipe tracepoints to printk */
 static struct trace_iterator *tracepoint_print_iter;
-int tracepoint_printk;
+static int tracepoint_printk;
 static bool tracepoint_printk_stop_on_boot __initdata;
 static bool traceoff_after_boot __initdata;
 static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
@@ -5015,7 +5015,6 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
 						RING_BUFFER_ALL_CPUS);
 		if (ret < 0)
 			return ret;
-		ret = 0;
 	}
 
 	list_for_each_entry(t, &tr->tracers, list) {
@@ -6188,7 +6187,7 @@ char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
 {
 	int cpu = smp_processor_id();
 	char *buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
-	unsigned int cnt;
+	unsigned long long cnt;
 	int trys = 0;
 	int ret;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 80fe152af1dd..bf77331f56a4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1941,6 +1941,7 @@ struct event_trigger_data {
 	struct list_head		named_list;
 	struct event_trigger_data	*named_data;
 	struct llist_node		llist;
+	void				(*private_data_free)(struct event_trigger_data *data);
 };
 
 /* Avoid typos */
diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index b66d6196338d..bcd97cb24ac9 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -172,7 +172,8 @@ static bool eprobe_dyn_event_match(const char *system, const char *event,
 	if (!slash)
 		return false;
 
-	if (strncmp(ep->event_system, argv[0], slash - argv[0]))
+	if (strncmp(ep->event_system, argv[0], slash - argv[0]) ||
+	    ep->event_system[slash - argv[0]] != '\0')
 		return false;
 	if (strcmp(ep->event_name, slash + 1))
 		return false;
@@ -315,7 +316,7 @@ get_event_field(struct fetch_insn *code, void *rec)
 			val = (unsigned long)addr;
 			break;
 		case FILTER_PTR_STRING:
-			val = (unsigned long)(*(char *)addr);
+			val = *(unsigned long *)addr;
 			break;
 		default:
 			WARN_ON_ONCE(1);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c46e623e7e0d..956692856fa8 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1350,7 +1350,9 @@ __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
 		call = file->event_call;
 
 		/* If a module is specified, skip events that are not that module */
-		if (module && (!call->module || strcmp(module_name(call->module), module)))
+		if (module &&
+		    ((call->flags & TRACE_EVENT_FL_DYNAMIC) ||
+		     !call->module || strcmp(module_name(call->module), module)))
 			continue;
 
 		name = trace_event_name(call);
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 609325f57942..6385cd662d8d 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1056,11 +1056,9 @@ static int regex_match_end(char *str, struct regex *r, int len)
 	return 0;
 }
 
-static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused)
+static int regex_match_glob(char *str, struct regex *r, int len)
 {
-	if (glob_match(r->pattern, str))
-		return 1;
-	return 0;
+	return glob_match_len(r->pattern, str, len) ? 1 : 0;
 }
 
 /**
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 82ce492ab268..58d28cd1afa3 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6349,6 +6349,7 @@ static void event_hist_trigger_free(struct event_trigger_data *data)
 
 		trigger_data_free(data);
 
+		tracepoint_synchronize_unregister();
 		remove_hist_vars(hist_data);
 
 		unregister_field_var_hists(hist_data);
@@ -6388,6 +6389,7 @@ static void event_hist_trigger_named_free(struct event_trigger_data *data)
 
 		del_named_trigger(data);
 		trigger_data_free(data);
+		tracepoint_synchronize_unregister();
 		kfree(cmd_ops);
 	}
 }
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index e6871230bde9..dc15658a887c 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -839,8 +839,10 @@ static struct synth_field *parse_synth_field(int argc, char **argv,
 			seq_buf_puts(&s, "__data_loc ");
 			seq_buf_puts(&s, field->type);
 
-			if (WARN_ON_ONCE(!seq_buf_buffer_left(&s)))
+			if (WARN_ON_ONCE(!seq_buf_buffer_left(&s))) {
+				kfree(type);
 				goto free;
+			}
 			s.buffer[s.len] = '\0';
 
 			kfree(field->type);
@@ -1446,13 +1448,13 @@ static int __create_synth_event(const char *name, const char *raw_fields)
 			if (cmd_version > 1 && n_fields_this_loop >= 1) {
 				synth_err(SYNTH_ERR_INVALID_CMD, errpos(field_str));
 				ret = -EINVAL;
-				goto err_free_arg;
+				goto err_free_field;
 			}
 
 			if (n_fields == SYNTH_FIELDS_MAX) {
 				synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0);
 				ret = -EINVAL;
-				goto err_free_arg;
+				goto err_free_field;
 			}
 			fields[n_fields++] = field;
 
@@ -1491,6 +1493,8 @@ static int __create_synth_event(const char *name, const char *raw_fields)
 	kfree(saved_fields);
 
 	return ret;
+ err_free_field:
+	free_synth_field(field);
  err_free_arg:
 	argv_free(argv);
  err:
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 655db2e82513..ad83419cb420 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -38,6 +38,13 @@ static void trigger_create_kthread_locked(void)
 	}
 }
 
+static void trigger_data_free_one(struct event_trigger_data *data)
+{
+	if (data->private_data_free)
+		data->private_data_free(data);
+	kfree(data);
+}
+
 static void trigger_data_free_queued_locked(void)
 {
 	struct event_trigger_data *data, *tmp;
@@ -52,7 +59,7 @@ static void trigger_data_free_queued_locked(void)
 	tracepoint_synchronize_unregister();
 
 	llist_for_each_entry_safe(data, tmp, llnodes, llist)
-		kfree(data);
+		trigger_data_free_one(data);
 }
 
 /* Bulk garbage collection of event_trigger_data elements */
@@ -75,7 +82,7 @@ static int trigger_kthread_fn(void *ignore)
 		tracepoint_synchronize_unregister();
 
 		llist_for_each_entry_safe(data, tmp, llnodes, llist)
-			kfree(data);
+			trigger_data_free_one(data);
 	}
 
 	return 0;
@@ -1717,6 +1724,14 @@ int event_enable_trigger_print(struct seq_file *m,
 	return 0;
 }
 
+static void enable_trigger_private_data_free(struct event_trigger_data *data)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	trace_event_put_ref(enable_data->file->event_call);
+	kfree(enable_data);
+}
+
 void event_enable_trigger_free(struct event_trigger_data *data)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
@@ -1728,9 +1743,8 @@ void event_enable_trigger_free(struct event_trigger_data *data)
 	if (!data->ref) {
 		/* Remove the SOFT_MODE flag */
 		trace_event_enable_disable(enable_data->file, 0, 1);
-		trace_event_put_ref(enable_data->file->event_call);
+		data->private_data_free = enable_trigger_private_data_free;
 		trigger_data_free(data);
-		kfree(enable_data);
 	}
 }
 
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index c4ba484f7b38..8c82ecb735f4 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -109,6 +109,9 @@ struct user_event_enabler {
 
 	/* Track enable bit, flags, etc. Aligned for bitops. */
 	unsigned long		values;
+
+	/* Defer the event put and enabler free past an RCU grace period. */
+	struct rcu_work		put_rwork;
 };
 
 /* Bits 0-5 are for the bit to update upon enable/disable (0-63 allowed) */
@@ -396,17 +399,39 @@ error:
 	return NULL;
 };
 
-static void user_event_enabler_destroy(struct user_event_enabler *enabler,
-				       bool locked)
+static void delayed_user_event_enabler_put(struct work_struct *work)
 {
-	list_del_rcu(&enabler->mm_enablers_link);
+	struct user_event_enabler *enabler = container_of(to_rcu_work(work),
+			struct user_event_enabler, put_rwork);
 
 	/* No longer tracking the event via the enabler */
-	user_event_put(enabler->event, locked);
+	user_event_put(enabler->event, false);
 
+	/* Run from queue_rcu_work(), the RCU grace period has elapsed */
 	kfree(enabler);
 }
 
+static void user_event_enabler_destroy(struct user_event_enabler *enabler)
+{
+	list_del_rcu(&enabler->mm_enablers_link);
+
+	/*
+	 * The enabler is removed from an RCU-traversed list
+	 * (user_event_mm_dup() walks mm->enablers under rcu_read_lock() only),
+	 * and readers there dereference enabler->event and take a new ref on
+	 * it. Both the put of that event reference and the free of the enabler
+	 * therefore have to wait for a grace period so no reader can be looking
+	 * at the enabler or racing the last put of its event.
+	 *
+	 * The put itself must not run in RCU context: when it drops the last
+	 * reference user_event_put() takes event_mutex, which cannot be taken
+	 * from a softirq/RCU callback. Defer both to a work item scheduled
+	 * after a grace period via queue_rcu_work().
+	 */
+	INIT_RCU_WORK(&enabler->put_rwork, delayed_user_event_enabler_put);
+	queue_rcu_work(system_percpu_wq, &enabler->put_rwork);
+}
+
 static int user_event_mm_fault_in(struct user_event_mm *mm, unsigned long uaddr,
 				  int attempt)
 {
@@ -464,7 +489,7 @@ static void user_event_enabler_fault_fixup(struct work_struct *work)
 
 	/* User asked for enabler to be removed during fault */
 	if (test_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler))) {
-		user_event_enabler_destroy(enabler, true);
+		user_event_enabler_destroy(enabler);
 		goto out;
 	}
 
@@ -764,7 +789,7 @@ static void user_event_mm_destroy(struct user_event_mm *mm)
 	struct user_event_enabler *enabler, *next;
 
 	list_for_each_entry_safe(enabler, next, &mm->enablers, mm_enablers_link)
-		user_event_enabler_destroy(enabler, false);
+		user_event_enabler_destroy(enabler);
 
 	mmdrop(mm->mm);
 	kfree(mm);
@@ -2645,7 +2670,7 @@ static long user_events_ioctl_unreg(unsigned long uarg)
 			flags |= enabler->values & ENABLE_VAL_COMPAT_MASK;
 
 			if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler)))
-				user_event_enabler_destroy(enabler, true);
+				user_event_enabler_destroy(enabler);
 
 			/* Removed at least one */
 			ret = 0;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index f283391a4dc8..cd37f2013758 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -458,12 +458,12 @@ func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 	ftrace_func_t func;
 	u32 new_flags;
 
-	/* Do nothing if already set. */
-	if (!!set == !!(tr->current_trace_flags->val & bit))
+	/* We can change this flag only when current tracer is function. */
+	if (tr->current_trace != &function_trace)
 		return 0;
 
-	/* We can change this flag only when not running. */
-	if (tr->current_trace != &function_trace)
+	/* Do nothing if already set. */
+	if (!!set == !!(tr->current_trace_flags->val & bit))
 		return 0;
 
 	new_flags = (tr->current_trace_flags->val & ~bit) | (set ? bit : 0);
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 226cf66e0d68..b88b8d9923ad 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -109,7 +109,6 @@ static void mmio_pipe_open(struct trace_iterator *iter)
 	iter->private = hiter;
 }
 
-/* XXX: This is not called when the pipe is closed! */
 static void mmio_close(struct trace_iterator *iter)
 {
 	struct header_iter *hiter = iter->private;
@@ -146,7 +145,7 @@ static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
 		goto print_out;
 	}
 
-	if (!hiter)
+	if (!hiter || !hiter->dev)
 		return 0;
 
 	mmio_print_pcidev(s, hiter->dev);
@@ -279,6 +278,7 @@ static struct tracer mmio_tracer __read_mostly =
 	.start		= mmio_trace_start,
 	.pipe_open	= mmio_pipe_open,
 	.close		= mmio_close,
+	.pipe_close	= mmio_close,
 	.read		= mmio_read,
 	.print_line	= mmio_print_line,
 	.noboot		= true,
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 5e83c4f6f2b4..0e1265acd1cc 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -179,7 +179,9 @@ static void osnoise_unregister_instance(struct trace_array *tr)
 	if (!found)
 		return;
 
-	kvfree_rcu_mightsleep(inst);
+	/* Do a full sync to ensure that tr remains valid, not just inst */
+	synchronize_rcu();
+	kvfree(inst);
 }
 
 /*
diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c
index 0c42b15c3800..b63e3558948f 100644
--- a/kernel/trace/trace_preemptirq.c
+++ b/kernel/trace/trace_preemptirq.c
@@ -30,7 +30,7 @@
 #else
 #define trace(point, args)					\
 	do {							\
-		if (trace_##point##_enabled()) {		\
+		if (__trace_##point##_enabled()) {		\
 			bool exit_rcu = false;			\
 			if (in_nmi())				\
 				break;				\
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index fd1caa1f9723..506e6037e163 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -188,7 +188,7 @@ void __trace_probe_log_err(int offset, int err_type)
 
 	lockdep_assert_held(&dyn_event_ops_mutex);
 
-	if (!trace_probe_log.argv)
+	if (!trace_probe_log.argv || !trace_probe_log.argc)
 		return;
 
 	/* Recalculate the length and allocate buffer */
@@ -342,10 +342,6 @@ static int parse_trace_event(char *arg, struct fetch_insn *code,
 	ret = parse_trace_event_arg(arg, code, ctx);
 	if (!ret)
 		return 0;
-	if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) {
-		code->op = FETCH_OP_COMM;
-		return 0;
-	}
 	return -EINVAL;
 }
 
@@ -678,7 +674,7 @@ static int parse_btf_arg(char *varname,
 	int i, is_ptr, ret;
 	u32 tid;
 
-	if (WARN_ON_ONCE(!ctx->funcname && !(ctx->flags & TPARG_FL_TEVENT)))
+	if (!ctx->funcname && !(ctx->flags & TPARG_FL_TEVENT))
 		return -EINVAL;
 
 	is_ptr = split_next_field(varname, &field, ctx);
@@ -1068,8 +1064,14 @@ static int parse_probe_vars(char *orig_arg, const struct fetch_type *t,
 	int len;
 
 	if (ctx->flags & TPARG_FL_TEVENT) {
-		if (parse_trace_event(arg, code, ctx) < 0)
+		if (parse_trace_event(arg, code, ctx) < 0) {
+			/* 'comm' should be checked after field parsing. */
+			if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) {
+				code->op = FETCH_OP_COMM;
+				return 0;
+			}
 			goto inval;
+		}
 		return 0;
 	}
 
@@ -1241,6 +1243,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
 
 			code->op = FETCH_OP_FOFFS;
 			code->immediate = (unsigned long)offset;  // imm64?
+			offset = 0;
 		} else {
 			/* uprobes don't support symbols */
 			if (!(ctx->flags & TPARG_FL_KERNEL)) {
@@ -2010,7 +2013,7 @@ int traceprobe_update_arg(struct probe_arg *arg)
 }
 
 /* When len=0, we just calculate the needed length */
-#define LEN_OR_ZERO (len ? len - pos : 0)
+#define LEN_OR_ZERO (len > pos ? len - pos : 0)
 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 			   enum probe_print_type ptype)
 {
@@ -2335,16 +2338,17 @@ int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b)
 bool trace_probe_match_command_args(struct trace_probe *tp,
 				    int argc, const char **argv)
 {
-	char buf[MAX_ARGSTR_LEN + 1];
 	int i;
 
 	if (tp->nr_args < argc)
 		return false;
 
 	for (i = 0; i < argc; i++) {
-		snprintf(buf, sizeof(buf), "%s=%s",
-			 tp->args[i].name, tp->args[i].comm);
-		if (strcmp(buf, argv[i]))
+		int len = strlen(tp->args[i].name);
+
+		if (strncmp(argv[i], tp->args[i].name, len) ||
+		    argv[i][len] != '=' ||
+		    strcmp(argv[i] + len + 1, tp->args[i].comm))
 			return false;
 	}
 	return true;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 15758cc11fc6..0f09f7aaf93f 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -511,7 +511,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(NO_RETVAL,		"This function returns 'void' type"),	\
 	C(BAD_STACK_NUM,	"Invalid stack number"),		\
 	C(BAD_ARG_NUM,		"Invalid argument number"),		\
-	C(BAD_VAR,		"Invalid $-valiable specified"),	\
+	C(BAD_VAR,		"Invalid $-variable specified"),	\
 	C(BAD_REG_NAME,		"Invalid register name"),		\
 	C(BAD_MEM_ADDR,		"Invalid memory address"),		\
 	C(BAD_IMM,		"Invalid immediate value"),		\
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index 2a6cc000ec98..e6724f947170 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -979,43 +979,36 @@ EXPORT_SYMBOL_GPL(trace_remote_free_buffer);
 int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, size_t buffer_size,
 			      const struct cpumask *cpumask)
 {
+	size_t min_desc_size = trace_buffer_desc_size(buffer_size, cpumask_weight(cpumask));
 	unsigned int nr_pages = max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) + 1;
-	void *desc_end = desc + desc_size;
 	struct ring_buffer_desc *rb_desc;
 	int cpu, ret = -ENOMEM;
 
-	if (desc_size < struct_size(desc, __data, 0))
+	if (desc_size < min_desc_size)
 		return -EINVAL;
 
 	desc->nr_cpus = 0;
-	desc->struct_len = struct_size(desc, __data, 0);
+	desc->struct_len = min_desc_size;
 
-	rb_desc = (struct ring_buffer_desc *)&desc->__data[0];
+	rb_desc = __first_ring_buffer_desc(desc);
 
 	for_each_cpu(cpu, cpumask) {
 		unsigned int id;
 
-		if ((void *)rb_desc + struct_size(rb_desc, page_va, nr_pages) > desc_end) {
-			ret = -EINVAL;
-			goto err;
-		}
-
 		rb_desc->cpu = cpu;
 		rb_desc->nr_page_va = 0;
 		rb_desc->meta_va = (unsigned long)__get_free_page(GFP_KERNEL);
 		if (!rb_desc->meta_va)
 			goto err;
 
+		desc->nr_cpus++;
+
 		for (id = 0; id < nr_pages; id++) {
+			rb_desc->nr_page_va++;
 			rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL);
 			if (!rb_desc->page_va[id])
 				goto err;
-
-			rb_desc->nr_page_va++;
 		}
-		desc->nr_cpus++;
-		desc->struct_len += offsetof(struct ring_buffer_desc, page_va);
-		desc->struct_len += struct_size(rb_desc, page_va, rb_desc->nr_page_va);
 		rb_desc = __next_ring_buffer_desc(rb_desc);
 	}
 
@@ -1156,10 +1149,21 @@ static ssize_t remote_events_dir_enable_write(struct file *filp, const char __us
 
 	for (i = 0; i < remote->nr_events; i++) {
 		struct remote_event *evt = &remote->events[i];
+		int eret;
 
-		trace_remote_enable_event(remote, evt, enable);
+		eret = trace_remote_enable_event(remote, evt, enable);
+		/*
+		 * Save the first error and return that. Some events
+		 * may still have been enabled, but let the user
+		 * know that something went wrong.
+		 */
+		if (!ret && eret)
+			ret = eret;
 	}
 
+	if (ret)
+		return ret;
+
 	return count;
 }
 
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index e98ee7e1e66f..8a4f3c75e39f 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1451,6 +1451,11 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 		if (syscall_get_data(sys_data, args, &user_ptr,
 				     &size, user_sizes, &uargs, buf_size) < 0)
 			return;
+
+		/* The above may have caused a migration */
+		head = this_cpu_ptr(sys_data->enter_event->perf_events);
+		if (hlist_empty(head))
+			return;
 	}
 
 	/* get the size after alignment with the u32 buffer size field */