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Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull scheduler fixes from Thomas Gleixner:
 "Three small fixes in the scheduler/core:

   - use after free in the numa code
   - crash in the numa init code
   - a simple spelling fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  pid: Fix spelling in comments
  sched/numa: Fix use-after-free bug in the task_numa_compare
  sched: Fix crash in sched_init_numa()
This commit is contained in:
Linus Torvalds 2016-01-31 15:44:04 -08:00
commit 7ab85d4a85
3 changed files with 25 additions and 9 deletions
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2
kernel/pid.c
View File

@ -588,7 +588,7 @@ void __init pidhash_init(void)
void __init pidmap_init(void)
{
/* Veryify no one has done anything silly */
/* Verify no one has done anything silly: */
BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);
/* bump default and minimum pid_max based on number of cpus */

2
kernel/sched/core.c
View File

@ -6840,7 +6840,7 @@ static void sched_init_numa(void)
sched_domains_numa_masks[i][j] = mask;
for (k = 0; k < nr_node_ids; k++) {
for_each_node(k) {
if (node_distance(j, k) > sched_domains_numa_distance[i])
continue;

30
kernel/sched/fair.c
View File

@ -1220,8 +1220,6 @@ static void task_numa_assign(struct task_numa_env *env,
{
if (env->best_task)
put_task_struct(env->best_task);
if (p)
get_task_struct(p);
env->best_task = p;
env->best_imp = imp;
@ -1289,20 +1287,30 @@ static void task_numa_compare(struct task_numa_env *env,
long imp = env->p->numa_group ? groupimp : taskimp;
long moveimp = imp;
int dist = env->dist;
bool assigned = false;
rcu_read_lock();
raw_spin_lock_irq(&dst_rq->lock);
cur = dst_rq->curr;
/*
* No need to move the exiting task, and this ensures that ->curr
* wasn't reaped and thus get_task_struct() in task_numa_assign()
* is safe under RCU read lock.
* Note that rcu_read_lock() itself can't protect from the final
* put_task_struct() after the last schedule().
* No need to move the exiting task or idle task.
*/
if ((cur->flags & PF_EXITING) || is_idle_task(cur))
cur = NULL;
else {
/*
* The task_struct must be protected here to protect the
* p->numa_faults access in the task_weight since the
* numa_faults could already be freed in the following path:
* finish_task_switch()
* --> put_task_struct()
* --> __put_task_struct()
* --> task_numa_free()
*/
get_task_struct(cur);
}
raw_spin_unlock_irq(&dst_rq->lock);
/*
@ -1386,6 +1394,7 @@ balance:
*/
if (!load_too_imbalanced(src_load, dst_load, env)) {
imp = moveimp - 1;
put_task_struct(cur);
cur = NULL;
goto assign;
}
@ -1411,9 +1420,16 @@ balance:
env->dst_cpu = select_idle_sibling(env->p, env->dst_cpu);
assign:
assigned = true;
task_numa_assign(env, cur, imp);
unlock:
rcu_read_unlock();
/*
* The dst_rq->curr isn't assigned. The protection for task_struct is
* finished.
*/
if (cur && !assigned)
put_task_struct(cur);
}
static void task_numa_find_cpu(struct task_numa_env *env,