Re: [patch] user-vm-unlock-2.5.31-A2

[Ingo Molnar]

On Thu, 15 Aug 2002, Linus Torvalds wrote:

> > we could skip the 'clear' bit if this is the last release of the mm.
> 
> Ahhah, but you miss the point.
> 
> The fork()'ed child may clone on its own, and then exit. [...]

i was actually thinking about exactly this scenario when suggesting this.  
The fork()ed child might as well end up being a 'thread' that exits and
thus needs to clear up after itself, right?

> [...] In which case we sure as heck don't want the original child to
> modify the VM that it now shares with a subthread.

in what way is clone() utilized? if it's via any threading library then
the fork()-ed process has its own thread state, which must be freed when
exiting. So it's something like:

	thread X
	fork()		===============>  thread Y
					  clone() ===========>  thread Z

so we at this point have the original thread X, a new thread Y that was
created via the fork(), and thread Z. Thread Y and Z share the same V. If
now thread Y exits:

					   exit()

then we'd sure expect for Z's sake to free Y's thread state, right?  
Otherwise there would be a resource leak.

[ but it's getting late here and i might miss something :) ]

	Ingo