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authorTejun Heo <tj@kernel.org>2012-10-16 15:03:14 -0700
committerTejun Heo <tj@kernel.org>2012-10-16 15:03:14 -0700
commit3c426d5e114035d00453bb5d82a92826db1ed71f (patch)
treeabb6a8f7d1dc278e2acd76f8a73baa39ddd8ff4e
parent51f246ed95caed12898649d8170d2d352da6af76 (diff)
downloadlinux-3c426d5e114035d00453bb5d82a92826db1ed71f.tar.bz2
cgroup_freezer: don't stall transition to FROZEN for PF_NOFREEZE or PF_FREEZER_SKIP tasks
cgroup_freezer doesn't transition from FREEZING to FROZEN if the cgroup contains PF_NOFREEZE tasks or tasks sleeping with PF_FREEZER_SKIP set. Only kernel tasks can be non-freezable (PF_NOFREEZE) and there's nothing cgroup_freezer or userland can do about or to it. It's pointless to stall the transition for PF_NOFREEZE tasks. PF_FREEZER_SKIP indicates that the task can be skipped when determining whether frozen state is reached. A task with PF_FREEZER_SKIP is guaranteed to perform try_to_freeze() after it wakes up and can be considered frozen much like stopped or traced tasks. Note that a vfork parent uses PF_FREEZER_SKIP while waiting for the child. This updates update_if_frozen() such that it only considers freezable tasks and treats %true freezer_should_skip() tasks as frozen. This allows cgroups w/ kthreads and vfork parents successfully reach FROZEN state. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rafael J. Wysocki <rjw@sisk.pl>
-rw-r--r--kernel/cgroup_freezer.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 05d52185139c..557f3678c4e4 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -214,10 +214,18 @@ static void update_if_frozen(struct cgroup *cgroup,
cgroup_iter_start(cgroup, &it);
while ((task = cgroup_iter_next(cgroup, &it))) {
- ntotal++;
- if (freezing(task) && (frozen(task) ||
- task_is_stopped_or_traced(task)))
- nfrozen++;
+ if (freezing(task)) {
+ ntotal++;
+ /*
+ * freezer_should_skip() indicates that the task
+ * should be skipped when determining freezing
+ * completion. Consider it frozen in addition to
+ * the usual frozen condition.
+ */
+ if (frozen(task) || task_is_stopped_or_traced(task) ||
+ freezer_should_skip(task))
+ nfrozen++;
+ }
}
if (old_state == CGROUP_THAWED) {