Recently met a don't understand the question, before using the 2.6 version of 32 m of the kernel, the kernel remaining available memory is lower than 1 m, the system function can also perform casually, now switch to the 3.1 version of the 64 m kernel, memory remaining below 15 m sysytem functions can return failed () returns 1,
System function will be called the fock copying the stack information of the parent, theoretically fock execution time do need to refer to the parent process of memory consumption, 2.6 version should also have a question, but I'm 2.6 kernel, a large amount of the application for many years, has been good, isn't the 2.6 kernel system strictly fock out process?

Small white solution!!!!!!