Re: [patch] threading fix, tid-2.5.47-A3

[Linus Torvalds]

On 18 Nov 2002, Alan Cox wrote:
> 
> What is the behaviour of someone setting VM_DONTCOPY on memory that was
> copy on write between a large number of processes (say an executable
> image) ?  Don't copy - but don't copy from what, from the original
> mapping or from the COW mapping of the original mapping ?

It literally means to not copy that VMA _at_all_. Basically, the mapping
simply won't show up in the child. It's kind of the mapping equivalent of
close-on-exec..

NOTE! Ingo - you might want to check with the shared-page-table people
about this, I remember us talking about discontinuing the feature because
it makes shared page tables harder to implement. Other than that it's a
trivial feature.

		Linus