Messages in this thread Patch in this message | | | Date | Wed, 31 Aug 2011 12:21:07 +0200 | From | Tejun Heo <> | Subject | [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() |
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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@kernel.org> Reported-by: Oleg Nesterov <oleg@redhat.com> Cc: Paul Menage <paul@paulmenage.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> --- 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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