That's what mmap is for :) When a read call completes, you know you've successfully read the data from the underlying device. If you have swap disabled you kno

That's what mmap is for :) When a read call completes, you know you've successfully read the data from the underlying device. If you have swap disabled you know you can read and write from that memory quickly. With mmap'd data, a memory read/write can trigger a page fault and I/O, and if you encounter an error like a network filesystem not responding in time, the program sees a segfault.