1 files changed, 50 insertions, 11 deletions

diff --git a/kernel/padata.c b/kernel/padata.c
index 9e18dfa372a9..57ec4eb5f2e3 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -516,12 +516,27 @@ static void padata_replace(struct padata_instance *pinst,
 
         synchronize_rcu();
 
-        padata_flush_queues(pd_old);
-        padata_free_pd(pd_old);
+        if (pd_old) {
+                padata_flush_queues(pd_old);
+                padata_free_pd(pd_old);
+        }
 
         pinst->flags &= ~PADATA_RESET;
 }
 
+/* If cpumask contains no active cpu, we mark the instance as invalid. */
+static bool padata_validate_cpumask(struct padata_instance *pinst,
+                                    const struct cpumask *cpumask)
+{
+        if (!cpumask_intersects(cpumask, cpu_active_mask)) {
+                pinst->flags |= PADATA_INVALID;
+                return false;
+        }
+
+        pinst->flags &= ~PADATA_INVALID;
+        return true;
+}
+
 /**
  * padata_set_cpumask - set the cpumask that padata should use
  *
@@ -531,11 +546,18 @@ static void padata_replace(struct padata_instance *pinst,
 int padata_set_cpumask(struct padata_instance *pinst,
                         cpumask_var_t cpumask)
 {
-        struct parallel_data *pd;
+        int valid;
         int err = 0;
+        struct parallel_data *pd = NULL;
 
         mutex_lock(&pinst->lock);
 
+        valid = padata_validate_cpumask(pinst, cpumask);
+        if (!valid) {
+                __padata_stop(pinst);
+                goto out_replace;
+        }
+
         get_online_cpus();
 
         pd = padata_alloc_pd(pinst, cpumask);
@@ -544,10 +566,14 @@ int padata_set_cpumask(struct padata_instance *pinst,
                 goto out;
         }
 
+out_replace:
         cpumask_copy(pinst->cpumask, cpumask);
 
         padata_replace(pinst, pd);
 
+        if (valid)
+                __padata_start(pinst);
+
 out:
         put_online_cpus();
 
@@ -567,6 +593,9 @@ static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
                         return -ENOMEM;
 
                 padata_replace(pinst, pd);
+
+                if (padata_validate_cpumask(pinst, pinst->cpumask))
+                        __padata_start(pinst);
         }
 
         return 0;
@@ -597,9 +626,16 @@ EXPORT_SYMBOL(padata_add_cpu);
 
 static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
 {
-        struct parallel_data *pd;
+        struct parallel_data *pd = NULL;
 
         if (cpumask_test_cpu(cpu, cpu_online_mask)) {
+
+                if (!padata_validate_cpumask(pinst, pinst->cpumask)) {
+                        __padata_stop(pinst);
+                        padata_replace(pinst, pd);
+                        goto out;
+                }
+
                 pd = padata_alloc_pd(pinst, pinst->cpumask);
                 if (!pd)
                         return -ENOMEM;
@@ -607,6 +643,7 @@ static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
                 padata_replace(pinst, pd);
         }
 
+out:
         return 0;
 }
 
@@ -732,7 +769,7 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
                                      struct workqueue_struct *wq)
 {
         struct padata_instance *pinst;
-        struct parallel_data *pd;
+        struct parallel_data *pd = NULL;
 
         pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
         if (!pinst)
@@ -740,12 +777,14 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
 
         get_online_cpus();
 
-        pd = padata_alloc_pd(pinst, cpumask);
-        if (!pd)
+        if (!alloc_cpumask_var(&pinst->cpumask, GFP_KERNEL))
                 goto err_free_inst;
 
-        if (!alloc_cpumask_var(&pinst->cpumask, GFP_KERNEL))
-                goto err_free_pd;
+        if (padata_validate_cpumask(pinst, cpumask)) {
+                pd = padata_alloc_pd(pinst, cpumask);
+                if (!pd)
+                        goto err_free_mask;
+        }
 
         rcu_assign_pointer(pinst->pd, pd);
 
@@ -767,8 +806,8 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
 
         return pinst;
 
-err_free_pd:
-        padata_free_pd(pd);
+err_free_mask:
+        free_cpumask_var(pinst->cpumask);
 err_free_inst:
         kfree(pinst);
         put_online_cpus();