kernel: pipe: limit the per-user amount of pages allocated in pipes

It is possible for a single process to cause an OOM condition by filling large pipes with data that are never read. A typical process filling 4096 pipes with 1 MB of data will use 4 GB of memory and there can be multiple such processes, up to a per-user-limit...

kernel: pipe: limit the per-user amount of pages allocated in pipes

It is possible for a single process to cause an OOM condition by filling large pipes with data that are never read. A typical process filling 4096 pipes with 1 MB of data will use 4 GB of memory and there can be multiple such processes, up to a per-user-limit...