diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 0582f67fbefc42bf88c0b7861aa21afbf6333011..1c173ccb0ef2849233ea2d3a5e8b089267fbebcc 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -607,6 +607,8 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist,
 	evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, prot,
 				      MAP_SHARED, fd, 0);
 	if (evlist->mmap[idx].base == MAP_FAILED) {
+		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
+			  errno);
 		evlist->mmap[idx].base = NULL;
 		return -1;
 	}