Re: odd timing bug with cgroups?

From: Chris Friesen
Date: Mon Jun 16 2008 - 12:45:35 EST


Valdis.Kletnieks@xxxxxx wrote:
On Fri, 13 Jun 2008 15:38:29 MDT, Chris Friesen said:

This seems odd...I would think that as soon as the fork() call returns in the parent we should be able to put that task into a group.

I'm admittedly shooting in the dark here, but remember that a successful
fork() call returns *twice*. Just because the *parent* has returned
doesn't mean that the *child* has finished all the processing and returned
as well - it may be delayed by other kernel threads etc and still not quite
ready for tweaking.

I was thinking something like this as well, like maybe we can't move the child to another group until it gets scheduled in once, or something similar.

If that is the case, I think it's a bug--on return from fork() the child's pid is visible (because the parent knows it) and so it should be valid to use for any operation that takes a pid.

Chris
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