Messages in this thread | | | From | Paul Menage <> | Date | Sun, 11 Sep 2011 21:11:16 -0700 | Subject | Re: [PATCHSET cgroup] extend threadgroup locking |
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On Sun, Sep 4, 2011 at 11:01 AM, Tejun Heo <htejun@gmail.com> wrote: > Hello, > > cgroup currently only blocks new threads from joining the target > threadgroup during migration, and on-going migration could race > against exec and exit leading to interesting problems - the symmetry > between various attach methods, task exiting during method execution, > ->exit() racing against attach methods, migrating task switching basic > properties during exec and so on. > > This patchset extends threadgroup locking such that it covers all > operations which can alter the threadgroup - fork, exit and exec, and > update cgroup to take advantage of it. rwsem read ops are added to > exit path but exec is excluded by grabbing the existing > cred_guard_mutex from threadgroup locking helper. > > This makes threadgroup locking complete and resolves cgroup issues > stemming from the target taskset being unstable. > > This patchset is on top of the current pm-freezer + "freezer: fixes & > simplifications" patchset and contains the following four patches. > Patch list and diffstat follow. > > Thanks. > > [PATCH 1/4] cgroup: change locking order in attach_task_by_pid() > [PATCH 2/4] threadgroup: rename signal->threadgroup_fork_lock to > [PATCH 3/4] threadgroup: extend threadgroup_lock() to cover exit and > [PATCH 4/4] cgroup: always lock threadgroup during migration >
Looks like a nice cleanup from the cgroups point of view. Hopefully Oleg or other folks who have a handle on the performance impact of the changes in the exit/exec code are happy with it.
Acked-by: Paul Menage <paul@paulmenage.org>
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