alt Hacker NewsThe point of disabling overcommit, as per the article, is that all pages in virtual memory must be backed by physical memory at all times. Therefore all virtual memory must reserve physical memory at the time of the fork call, even if the contents of the pages only get copied when they are touched.
Surely e.g. shared memory segments that are mapped by multiple processes are not double-counted? So it's only COW memory in particular that gets this treatment? Linux could just not do that.