From mboxrd@z Thu Jan  1 00:00:00 1970
From: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Subject: Re: [patch 100/148] cgroups: convert tasks file to use a seq_file
	with shared pid array
Date: Thu, 18 Jun 2009 09:41:33 +0800
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To: Paul Menage <menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Linux Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
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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.