The update_flag() is called with one flag bit change and without change in the various cpumasks in the cpuset. Moreover, not all changes in the flag bits are validated in validate_change(). In particular, the load balance flag and the two spread flags are not checked there. So there is no point in calling validate_change() if those flag bits change.
Signed-off-by: Waiman Long longman@redhat.com --- kernel/cgroup/cpuset.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index adb5190c4429..65ad6995ad77 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1891,7 +1891,7 @@ static void update_tasks_flags(struct cpuset *cs) * cs: the cpuset to update * turning_on: whether the flag is being set or cleared * - * Call with cpuset_mutex held. + * Call with cpuset_mutex held & cpumasks remain unchanged. */
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, @@ -1911,16 +1911,22 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, else clear_bit(bit, &trialcs->flags);
- err = validate_change(cs, trialcs); - if (err < 0) - goto out; - balance_flag_changed = (is_sched_load_balance(cs) != is_sched_load_balance(trialcs));
spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs)) || (is_spread_page(cs) != is_spread_page(trialcs)));
+ /* + * validate_change() doesn't validate changes in load balance + * and spread flags. + */ + if (!balance_flag_changed && !spread_flag_changed) { + err = validate_change(cs, trialcs); + if (err < 0) + goto out; + } + spin_lock_irq(&callback_lock); cs->flags = trialcs->flags; spin_unlock_irq(&callback_lock);