The Linux kernel supports three overcommit handling modes 0 - Heuristic overcommit handling. Obvious overcommits of address space are refused. Used for a typical system. It ensures a seriously wild allocation fails while allowing overcommit to reduce swap usage. root is allowed to allocate slighly more memory in this mode. This is the default. 1 - No overcommit handling. Appropriate for some scientific applications. 2 - (NEW) strict overcommit. The total address space commit for the system is not permitted to exceed swap + a configurable percentage (default is 50) of physical RAM. Depending on the percentage you use, in most situations this means a process will not be killed while accessing pages but will receive errors on memory allocation as appropriate. The overcommit policy is set via the sysctl `vm.overcommit_memory'. The overcommit percentage is set via `vm.overcommit_ratio'.