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cgroup_freezer: cgroup_freezing: Check if not frozen
__thaw_task() was recently updated to warn if the task being thawed was
part of a freezer cgroup that is still currently freezing:
void __thaw_task(struct task_struct *p)
{
...
if (WARN_ON_ONCE(freezing(p)))
goto unlock;
This has exposed a bug in cgroup1 freezing where when CGROUP_FROZEN is
asserted, the CGROUP_FREEZING bits are not also cleared at the same
time. Meaning, when a cgroup is marked FROZEN it continues to be marked
FREEZING as well. This causes the WARNING to trigger, because
cgroup_freezing() thinks the cgroup is still freezing.
There are two ways to fix this:
1. Whenever FROZEN is set, clear FREEZING for the cgroup and all
children cgroups.
2. Update cgroup_freezing() to also verify that FROZEN is not set.
This patch implements option (2), since it's smaller and more
straightforward.
Signed-off-by: Tim Van Patten <timvp@google.com>
Tested-by: Mark Hasemeyer <markhas@chromium.org>
Fixes: f5d39b0208
("freezer,sched: Rewrite core freezer logic")
Cc: stable@vger.kernel.org # v6.1+
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
parent
037266a5f7
commit
cff5f49d43
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@ -66,9 +66,15 @@ static struct freezer *parent_freezer(struct freezer *freezer)
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bool cgroup_freezing(struct task_struct *task)
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bool cgroup_freezing(struct task_struct *task)
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{
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{
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bool ret;
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bool ret;
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unsigned int state;
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rcu_read_lock();
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rcu_read_lock();
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ret = task_freezer(task)->state & CGROUP_FREEZING;
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/* Check if the cgroup is still FREEZING, but not FROZEN. The extra
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* !FROZEN check is required, because the FREEZING bit is not cleared
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* when the state FROZEN is reached.
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*/
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state = task_freezer(task)->state;
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ret = (state & CGROUP_FREEZING) && !(state & CGROUP_FROZEN);
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rcu_read_unlock();
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rcu_read_unlock();
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return ret;
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return ret;
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