On Thu, 2008-11-27 at 02:17 +0100, Bastian Blank wrote: > On Tue, Nov 25, 2008 at 07:45:28PM -0800, Sukadev Bhattiprolu wrote: > > Currently task_active_pid_ns is not safe to call after a > > task becomes a zombie and exit_task_namespaces is called, > > as nsproxy becomes NULL. > > Why do you need to be able to get the pid namespace from zombie > processes? Also according to nsproxy.h this access variant is only > allowed for the current task, anything else needs to take a rcu lock. > That doesn't save ->nsproxy to be NULL... as shown in the very same example you're talking about. I agree with Eric and Sukadev that task_active_pid_ns() is unsafe. There isn't even a /* don't use with zombies */ in pid_namespace.h... > > By reading the pid namespace from > > the pid of the task we can trivially solve this problem at > > the cost of one extra memory read in what should be the > > same cacheline as we read the namespace from. > > The pid namespace may not be destructed yet? > Yes as long as a pid from that namespace is still in use... -- Gregory Kurz gkurz@xxxxxxxxxx Software Engineer @ IBM/Meiosys http://www.ibm.com Tel +33 (0)534 638 479 Fax +33 (0)561 400 420 "Anarchy is about taking complete responsibility for yourself." Alan Moore. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
