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

[Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>]

Paul Menage wrote:
> 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
> pid array are always from the namespace of the last process to open

Hmm, so we have to keep namespace in mind whenever we deal with
pid..

> the file. 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).
> 

Sounds feasible.