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authorMichal Hocko <mhocko@suse.cz>2011-11-22 07:44:47 -0800
committerTejun Heo <tj@kernel.org>2011-11-24 11:58:22 -0800
commit884a45d964dd395eda945842afff5e16bcaedf56 (patch)
tree47a28f7231d65cff01f797ad1ad74e4a82a86839
parent860ca0e6f72d21ded33ce14be9a53eb103f88441 (diff)
cgroup_freezer: fix freezing groups with stopped tasks
2d3cbf8b (cgroup_freezer: update_freezer_state() does incorrect state transitions) removed is_task_frozen_enough and replaced it with a simple frozen call. This, however, breaks freezing for a group with stopped tasks because those cannot be frozen and so the group remains in CGROUP_FREEZING state (update_if_frozen doesn't count stopped tasks) and never reaches CGROUP_FROZEN. Let's add is_task_frozen_enough back and use it at the original locations (update_if_frozen and try_to_freeze_cgroup). Semantically we consider stopped tasks as frozen enough so we should consider both cases when testing frozen tasks. Testcase: mkdir /dev/freezer mount -t cgroup -o freezer none /dev/freezer mkdir /dev/freezer/foo sleep 1h & pid=$! kill -STOP $pid echo $pid > /dev/freezer/foo/tasks echo FROZEN > /dev/freezer/foo/freezer.state while true do cat /dev/freezer/foo/freezer.state [ "`cat /dev/freezer/foo/freezer.state`" = "FROZEN" ] && break sleep 1 done echo OK Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Tomasz Buchert <tomasz.buchert@inria.fr> Cc: Paul Menage <paul@paulmenage.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: stable@kernel.org Signed-off-by: Tejun Heo <htejun@gmail.com>
-rw-r--r--kernel/cgroup_freezer.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 5e828a2ca8e6..213c0351dad8 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -153,6 +153,13 @@ static void freezer_destroy(struct cgroup_subsys *ss,
kfree(cgroup_freezer(cgroup));
}
+/* task is frozen or will freeze immediately when next it gets woken */
+static bool is_task_frozen_enough(struct task_struct *task)
+{
+ return frozen(task) ||
+ (task_is_stopped_or_traced(task) && freezing(task));
+}
+
/*
* The call to cgroup_lock() in the freezer.state write method prevents
* a write to that file racing against an attach, and hence the
@@ -231,7 +238,7 @@ static void update_if_frozen(struct cgroup *cgroup,
cgroup_iter_start(cgroup, &it);
while ((task = cgroup_iter_next(cgroup, &it))) {
ntotal++;
- if (frozen(task))
+ if (is_task_frozen_enough(task))
nfrozen++;
}
@@ -284,7 +291,7 @@ static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
while ((task = cgroup_iter_next(cgroup, &it))) {
if (!freeze_task(task, true))
continue;
- if (frozen(task))
+ if (is_task_frozen_enough(task))
continue;
if (!freezing(task) && !freezer_should_skip(task))
num_cant_freeze_now++;