Is not locking task_lock in cgroup_fork() safe?

Tejun Heo tj at
Mon Oct 8 02:00:00 UTC 2012

Hello, Frederic.

7e381b0eb1 ("cgroup: Drop task_lock(parent) on cgroup_fork()") removed
task_lock from cgroup_fork citing that current->cgroups can't change
due to threadgroup_change locking; however, threadgroup_change locking
is used only during CLONE_THREAD forking.  If @current is forking a
new process, there's nothing preventing someone else to migrate the
parent while forking is in progress and delete the css_set it
currently is using.  Am I confused somewhere?



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