Messages in this thread Patch in this message | | | From | Michal Hocko <> | Subject | [PATCH] cgroup_freezer: fix freezing groups with stopped tasks | Date | Wed, 16 Nov 2011 22:50:34 +0100 |
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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> Cc: Tomasz Buchert <tomasz.buchert@inria.fr> Cc: Paul Menage <paul@paulmenage.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Tejun Heo <htejun@gmail.com> --- kernel/cgroup_freezer.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 5e828a2..4d073dc 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++; -- 1.7.7.1
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