If you allocate a relatively big chunk of memory for each unit of work, and at some point your allocation fails, you can just drop that unit of work. What is not practical?
I think in that case overcommit will happily say the allocation worked. Unless you also zero the entire chunk of memory and then get OOM killed on the write.
I suppose you can try to reliable target "seriously wild allocation fails" without leaving too much memory on the table.
0: Heuristic overcommit handling. Obvious overcommits of
address space are refused. Used for a typical system. It
ensures a seriously wild allocation fails while allowing
overcommit to reduce swap usage. root is allowed to
allocate slightly more memory in this mode. This is the
default.
