Re: More problems in dup_mmap

Linus Torvalds (
6 Aug 1997 22:38:57 GMT

In article <>,
Philip Gladstone <> wrote:
>I was thinking last night when I was driving home -- things like
>verify_area examine the mm, and this can be happening concurrently
>with other functions manipulating it. It seems that reader/writer
>locks are really required on this (and probably other) structures.

No. That's why we went for the new exception-based setup in 2.1.x for
user level accesses: verify_area() is no longer used except on i386
machines (where it is used only to check for the WP bug).

Essentially, in 2.1.x we have the hardware handle the thing for us, at
zero cost.