diff --git a/tools/perf/lib/evlist.c b/tools/perf/lib/evlist.c
index 73aac6bb2ac5..205ddbb80bc1 100644
--- a/tools/perf/lib/evlist.c
+++ b/tools/perf/lib/evlist.c
@@ -578,6 +578,8 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist,
 	if (!ops || !ops->get || !ops->mmap)
 		return -EINVAL;
 
+	mp->mask = evlist->mmap_len - page_size - 1;
+
 	evlist->nr_mmaps = perf_evlist__nr_mmaps(evlist);
 
 	perf_evlist__for_each_entry(evlist, evsel) {
@@ -605,7 +607,6 @@ int perf_evlist__mmap(struct perf_evlist *evlist, int pages)
 	};
 
 	evlist->mmap_len = (pages + 1) * page_size;
-	mp.mask = evlist->mmap_len - page_size - 1;
 
 	return perf_evlist__mmap_ops(evlist, &ops, &mp);
 }
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 5cded4ec5806..fdce590d2278 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -813,7 +813,6 @@ int evlist__mmap_ex(struct evlist *evlist, unsigned int pages,
 
 	evlist->core.mmap_len = evlist__mmap_size(pages);
 	pr_debug("mmap size %zuB\n", evlist->core.mmap_len);
-	mp.core.mask = evlist->core.mmap_len - page_size - 1;
 
 	auxtrace_mmap_params__init(&mp.auxtrace_mp, evlist->core.mmap_len,
 				   auxtrace_pages, auxtrace_overwrite);