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| author | Tejun Heo <tj@kernel.org> | 2012-10-16 15:03:14 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2012-10-16 15:03:14 -0700 |
| commit | 3c426d5e114035d00453bb5d82a92826db1ed71f (patch) | |
| tree | abb6a8f7d1dc278e2acd76f8a73baa39ddd8ff4e | |
| parent | 51f246ed95caed12898649d8170d2d352da6af76 (diff) | |
| download | linux-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.c | 16 |
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) { |