system contract should only allow producers to increase ram #3302

contracts/eosio.system/eosio.system.cpp

@@ -54,6 +54,7 @@ namespace eosiosystem {
    void system_contract::setram( uint64_t max_ram_size ) {
       require_auth( _self );
 
+      eosio_assert( _gstate.max_ram_size < max_ram_size, "ram can only be increased" ); /// decreasing ram might result market maker issues
       eosio_assert( max_ram_size < 1024ll*1024*1024*1024*1024, "ram size is unrealistic" );
       eosio_assert( max_ram_size > _gstate.total_ram_bytes_reserved, "attempt to set max below reserved" );