Why does malloc() fail when there is enough memory?

Question

I\'m using a server with 128GB memory to do some computation. I need to malloc() a 2D float array of size 56120 * 56120. An example code is as follows:

Answer 1

float ls[3149454400]; is an array with automatic storage type, which is usually allocated on the process stack. A process stack is limited by default by a value much smaller than 12GB you are attempting to push there. So the segmentation fault you are observing is caused by the stack overflow, rather than by the malloc.