5 files changed, 28 insertions, 2 deletions
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 93816542cd..62dd85e425 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -480,7 +480,7 @@ Eterm erts_hashmap_from_array(ErtsHeapFactory* factory, Eterm *leafs, Uint n,
 
 Eterm erts_map_from_ks_and_vs(ErtsHeapFactory *factory, Eterm *ks0, Eterm *vs0, Uint n)
 {
-    if (n < MAP_SMALL_MAP_LIMIT) {
+    if (n <= MAP_SMALL_MAP_LIMIT) {
         Eterm *ks, *vs, *hp;
 	flatmap_t *mp;
 	Eterm keys;
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index b762e0f6e7..82645d4091 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -2365,6 +2365,13 @@ static void dtor_demonitor(ErtsMonitor* mon, void* context)
     erts_proc_sig_send_demonitor(mon);
 }
 
+#ifdef DEBUG
+int erts_dbg_is_resource_dying(ErtsResource* resource)
+{
+    return resource->monitors && rmon_is_dying(resource->monitors);
+}
+#endif
+
 #  define NIF_RESOURCE_DTOR &nif_resource_dtor
 
 static int nif_resource_dtor(Binary* bin)
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 29de162b42..5d0dec7f08 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -113,6 +113,9 @@ extern Eterm erts_bld_resource_ref(Eterm** hp, ErlOffHeap*, ErtsResource*);
 extern void erts_pre_nif(struct enif_environment_t*, Process*,
 			 struct erl_module_nif*, Process* tracee);
 extern void erts_post_nif(struct enif_environment_t* env);
+#ifdef DEBUG
+int erts_dbg_is_resource_dying(ErtsResource*);
+#endif
 extern void erts_resource_stop(ErtsResource*, ErlNifEvent, int is_direct_call);
 void erts_fire_nif_monitor(ErtsMonitor *tmon);
 void erts_nif_demonitored(ErtsResource* resource);
diff --git a/erts/emulator/sys/common/erl_check_io.c b/erts/emulator/sys/common/erl_check_io.c
index d413659f81..e367087455 100644
--- a/erts/emulator/sys/common/erl_check_io.c
+++ b/erts/emulator/sys/common/erl_check_io.c
@@ -1061,7 +1061,7 @@ enif_select_x(ErlNifEnv* env,
     ErtsDrvSelectDataState *free_select = NULL;
     ErtsNifSelectDataState *free_nif = NULL;
 
-    ASSERT(!resource->monitors);
+    ASSERT(!erts_dbg_is_resource_dying(resource));
 
 #ifdef ERTS_SYS_CONTINOUS_FD_NUMBERS
     if (!grow_drv_ev_state(fd)) {
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 75b3cd2c14..168df76301 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1215,6 +1215,15 @@ maps(Config) when is_list(Config) ->
     M2 = maps_from_list_nif(maps:to_list(M2)),
     M3 = maps_from_list_nif(maps:to_list(M3)),
 
+    %% Test different map sizes (OTP-15567)
+    repeat_while(fun({35,_}) -> false;
+                    ({K,Map}) ->
+                         Map = maps_from_list_nif(maps:to_list(Map)),
+                         Map = maps:filter(fun(K,V) -> V =:= K*100 end, Map),
+                         {K+1, maps:put(K,K*100,Map)}
+                 end,
+                 {1,#{}}),
+
     has_duplicate_keys = maps_from_list_nif([{1,1},{1,1}]),
 
     verify_tmpmem(TmpMem),
@@ -2511,6 +2520,13 @@ repeat(0, _, Arg) ->
 repeat(N, Fun, Arg0) ->
     repeat(N-1, Fun, Fun(Arg0)).
 
+repeat_while(Fun, Acc0) ->
+    case Fun(Acc0) of
+        false -> ok;
+        Acc1 ->
+            repeat_while(Fun, Acc1)
+    end.
+
 check(Exp,Got,Line) ->
     case Got of
  	Exp -> Exp;