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| author | Tejun Heo <tj@kernel.org> | 2015-09-16 11:51:12 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-09-16 11:51:12 -0400 |
| commit | f9f9e7b776142fb1c0782cade004cc8e0147a199 (patch) | |
| tree | 53719cfc0bf81bc7e6fb522944553d9b4fa36cbf /kernel/fork.c | |
| parent | 6ff33f3902c3b1c5d0db6b1e2c70b6d76fba357f (diff) | |
| download | op-kernel-dev-f9f9e7b776142fb1c0782cade004cc8e0147a199.zip op-kernel-dev-f9f9e7b776142fb1c0782cade004cc8e0147a199.tar.gz | |
Revert "cgroup: simplify threadgroup locking"
This reverts commit b5ba75b5fc0e8404e2c50cb68f39bb6a53fc916f.
d59cfc09c32a ("sched, cgroup: replace signal_struct->group_rwsem with
a global percpu_rwsem") and b5ba75b5fc0e ("cgroup: simplify
threadgroup locking") changed how cgroup synchronizes against task
fork and exits so that it uses global percpu_rwsem instead of
per-process rwsem; unfortunately, the write [un]lock paths of
percpu_rwsem always involve synchronize_rcu_expedited() which turned
out to be too expensive.
Improvements for percpu_rwsem are scheduled to be merged in the coming
v4.4-rc1 merge window which alleviates this issue. For now, revert
the two commits to restore per-process rwsem. They will be re-applied
for the v4.4-rc1 merge window.
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org # v4.2+
Diffstat (limited to 'kernel/fork.c')
0 files changed, 0 insertions, 0 deletions
