1 files changed, 38 insertions, 20 deletions

diff --git a/kernel/sched_cpupri.c b/kernel/sched_cpupri.c
index 1e00bfacf9b8..0f052fc674d5 100644
--- a/kernel/sched_cpupri.c
+++ b/kernel/sched_cpupri.c
@@ -55,7 +55,7 @@ static int convert_prio(int prio)
  * cpupri_find - find the best (lowest-pri) CPU in the system
  * @cp: The cpupri context
  * @p: The task
- * @lowest_mask: A mask to fill in with selected CPUs
+ * @lowest_mask: A mask to fill in with selected CPUs (or NULL)
  *
  * Note: This function returns the recommended CPUs as calculated during the
  * current invokation.  By the time the call returns, the CPUs may have in
@@ -81,7 +81,21 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
                 if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
                         continue;
 
-                cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+                if (lowest_mask) {
+                        cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+
+                        /*
+                         * We have to ensure that we have at least one bit
+                         * still set in the array, since the map could have
+                         * been concurrently emptied between the first and
+                         * second reads of vec->mask.  If we hit this
+                         * condition, simply act as though we never hit this
+                         * priority level and continue on.
+                         */
+                        if (cpumask_any(lowest_mask) >= nr_cpu_ids)
+                                continue;
+                }
+
                 return 1;
         }
 
@@ -113,21 +127,11 @@ void cpupri_set(struct cpupri *cp, int cpu, int newpri)
 
         /*
          * If the cpu was currently mapped to a different value, we
-         * first need to unmap the old value
+         * need to map it to the new value then remove the old value.
+         * Note, we must add the new value first, otherwise we risk the
+         * cpu being cleared from pri_active, and this cpu could be
+         * missed for a push or pull.
          */
-        if (likely(oldpri != CPUPRI_INVALID)) {
-                struct cpupri_vec *vec  = &cp->pri_to_cpu[oldpri];
-
-                spin_lock_irqsave(&vec->lock, flags);
-
-                vec->count--;
-                if (!vec->count)
-                        clear_bit(oldpri, cp->pri_active);
-                cpumask_clear_cpu(cpu, vec->mask);
-
-                spin_unlock_irqrestore(&vec->lock, flags);
-        }
-
         if (likely(newpri != CPUPRI_INVALID)) {
                 struct cpupri_vec *vec = &cp->pri_to_cpu[newpri];
 
@@ -140,6 +144,18 @@ void cpupri_set(struct cpupri *cp, int cpu, int newpri)
 
                 spin_unlock_irqrestore(&vec->lock, flags);
         }
+        if (likely(oldpri != CPUPRI_INVALID)) {
+                struct cpupri_vec *vec  = &cp->pri_to_cpu[oldpri];
+
+                spin_lock_irqsave(&vec->lock, flags);
+
+                vec->count--;
+                if (!vec->count)
+                        clear_bit(oldpri, cp->pri_active);
+                cpumask_clear_cpu(cpu, vec->mask);
+
+                spin_unlock_irqrestore(&vec->lock, flags);
+        }
 
         *currpri = newpri;
 }
@@ -151,10 +167,14 @@ void cpupri_set(struct cpupri *cp, int cpu, int newpri)
  *
  * Returns: -ENOMEM if memory fails.
  */
-int __init_refok cpupri_init(struct cpupri *cp, bool bootmem)
+int cpupri_init(struct cpupri *cp, bool bootmem)
 {
+        gfp_t gfp = GFP_KERNEL;
         int i;
 
+        if (bootmem)
+                gfp = GFP_NOWAIT;
+
         memset(cp, 0, sizeof(*cp));
 
         for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) {
@@ -162,9 +182,7 @@ int __init_refok cpupri_init(struct cpupri *cp, bool bootmem)
 
                 spin_lock_init(&vec->lock);
                 vec->count = 0;
-                if (bootmem)
-                        alloc_bootmem_cpumask_var(&vec->mask);
-                else if (!alloc_cpumask_var(&vec->mask, GFP_KERNEL))
+                if (!zalloc_cpumask_var(&vec->mask, gfp))
                         goto cleanup;
         }