Re: [patch 100/148] cgroups: convert tasks file to use a seq_file with shared pid array

["Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

Quoting Paul Menage (menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org):
> It just struck me that this patch broke access to the tasks file in
> the presence of multiple pid namespaces, since the pids in the cached

Hmm, sure does.

> pid array are always from the namespace of the last process to open
> the file.

Well it's only around as long as the file is open, so I guess that's
another reason noone has hit this bug.  A task in pidns B must
open the file between the open and close by a task in pidns A.

> Since I suspect no-one uses pid namespaces in production
> environments this probably isn't a show-stopper, but to be technically
> correct we need to maintain a list of cached pid arrays keyed by pid
> namespace. (This list should generally be very short, usually of
> length 1).

Just to clarify - do you have a patch in the works for this, or are you
asking for the patch to be written?

thanks,
-serge