[PATCH -tip/cpus4096-v2] cpumask: fix memory leak and cpumask corruption

[Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>]

From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>

On CONFIG_CPUMASK_OFFSTACK enabled kernel, when exiting
smp_call_function_many() without calling arch_send_call_function_ipi()
allbutself should be freed.

Also, the memory for allbutself shouldn't be freed when
arch_send_call_function_ipi() is called.  The memory region will be
referenced in generic_smp_call_function_interrupt(). And the memory
will be freed at rcu_free_call_data().

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
---
 kernel/smp.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index da98191..96b39e3 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -88,6 +88,7 @@ static void rcu_free_call_data(struct rcu_head *head)
 	struct call_function_data *data;
 
 	data = container_of(head, struct call_function_data, rcu_head);
+	free_cpumask_var(data->cpumask);
 
 	kfree(data);
 }
@@ -347,7 +348,7 @@ void smp_call_function_many(const struct cpumask *mask,
 	 * into a targetted single call instead since it's faster.
 	 */
 	if (!num_cpus)
-		return;
+		goto out;
 	else if (num_cpus == 1) {
 		cpu = cpumask_first(allbutself);
 		smp_call_function_single(cpu, func, info, wait);
@@ -382,9 +383,12 @@ void smp_call_function_many(const struct cpumask *mask,
 	/* optionally wait for the CPUs to complete */
 	if (wait) {
 		csd_flag_wait(&data->csd);
-		if (unlikely(slowpath))
+		if (unlikely(slowpath)) {
 			smp_call_function_mask_quiesce_stack(allbutself);
+			free_cpumask_var(allbutself);
+		}
 	}
+	return;
 out:
 	free_cpumask_var(allbutself);
 }
-- 
1.5.6