d02f52811d0e "cgroup_freezer: prepare for removal of TIF_FREEZE" moved
setting of freezer->state into freezer_change_state(); unfortunately,
while doing so, when it's beginning to freeze tasks, it sets the state
to CGROUP_FROZEN instead of CGROUP_FREEZING ending up skipping the
whole freezing state. Fix it.
-v2: Oleg pointed out that re-freezing FROZEN cgroup could increment
system_freezing_cnt. Fixed.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Paul Menage <paul@xxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
---
I'm in the process of moving and can only use a quite old laptop. I
tested compile but couldn't really do much else, so please proceed
with caution. Oleg, can you please ack the patches if you agree with
the updated versions?
Thanks.
kernel/cgroup_freezer.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
Index: work/kernel/cgroup_freezer.c
===================================================================
--- work.orig/kernel/cgroup_freezer.c
+++ work/kernel/cgroup_freezer.c
@@ -308,24 +308,26 @@ static int freezer_change_state(struct c
spin_lock_irq(&freezer->lock);
update_if_frozen(cgroup, freezer);
- if (goal_state == freezer->state)
- goto out;
-
- freezer->state = goal_state;
switch (goal_state) {
case CGROUP_THAWED:
- atomic_dec(&system_freezing_cnt);
- unfreeze_cgroup(cgroup, freezer);
+ if (freezer->state != CGROUP_THAWED) {
+ freezer->state = CGROUP_THAWED;
+ atomic_dec(&system_freezing_cnt);
+ unfreeze_cgroup(cgroup, freezer);
+ }
break;
case CGROUP_FROZEN:
- atomic_inc(&system_freezing_cnt);
- retval = try_to_freeze_cgroup(cgroup, freezer);
+ if (freezer->state == CGROUP_THAWED) {
+ freezer->state = CGROUP_FREEZING;
+ atomic_inc(&system_freezing_cnt);
+ retval = try_to_freeze_cgroup(cgroup, freezer);
+ }
break;
default:
BUG();
}
-out:
+
spin_unlock_irq(&freezer->lock);
return retval;
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