Linux에서 익명 프로세스란 무엇입니까?

task_struct의 mm 필드와 active_mm 필드의 차이점을 이해하려고 노력 중입니다.리누스 토발즈가 20년 전에 보낸 이메일"익명 프로세스"라는 개념이 인용되었습니다.

 - we have "real address spaces" and "anonymous address spaces". The
   difference is that an anonymous address space doesn't care about the
   user-level page tables at all, so when we do a context switch into an
   anonymous address space we just leave the previous address space
   active.

   [...]

 - "tsk->mm" points to the "real address space". For an **anonymous process**,
   tsk->mm will be NULL, for the logical reason that an **anonymous process**
   really doesn't _have_ a real address space at all.

 - however, we obviously need to keep track of which address space we
   "stole" for such an anonymous user. For that, we have "tsk->active_mm",
   which shows what the currently active address space is.

   The rule is that for a process with a real address space (ie tsk->mm is
   non-NULL) the active_mm obviously always has to be the same as the real
   one.

   For a **anonymous process**, tsk->mm == NULL, and tsk->active_mm is the
   "borrowed" mm while the **anonymous process** is running. When the
   **anonymous process** gets scheduled away, the borrowed address space is
   returned and cleared.