>so that allocations by a given process reserve memory and may fail, but in return the kernel promises not to OOM kill it The issue with this is that there are

>so that allocations by a given process reserve memory and may fail, but in return the kernel promises not to OOM kill it The issue with this is that there are other processes on the system. If I start a program that used your idea for allocation, and it used 90% of my memory, a small growth in my memory usage might mean I run out. But because it's guaranteed not to OOM, another program gets killed rather than the one using 90% of the memory. If you want no OOM kills, you've got to disable overcommit globally.