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-rw-r--r--kernel/sched/core.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e205c191b7fb..7e5946698711 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2273,7 +2273,6 @@ static int migration_cpu_stop(void *data)
struct migration_arg *arg = data;
struct set_affinity_pending *pending = arg->pending;
struct task_struct *p = arg->task;
- int dest_cpu = arg->dest_cpu;
struct rq *rq = this_rq();
bool complete = false;
struct rq_flags rf;
@@ -2311,19 +2310,15 @@ static int migration_cpu_stop(void *data)
if (pending) {
p->migration_pending = NULL;
complete = true;
- }
- if (dest_cpu < 0) {
if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask))
goto out;
-
- dest_cpu = cpumask_any_distribute(&p->cpus_mask);
}
if (task_on_rq_queued(p))
- rq = __migrate_task(rq, &rf, p, dest_cpu);
+ rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
else
- p->wake_cpu = dest_cpu;
+ p->wake_cpu = arg->dest_cpu;
/*
* XXX __migrate_task() can fail, at which point we might end
@@ -2606,7 +2601,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
init_completion(&my_pending.done);
my_pending.arg = (struct migration_arg) {
.task = p,
- .dest_cpu = -1, /* any */
+ .dest_cpu = dest_cpu,
.pending = &my_pending,
};
@@ -2614,6 +2609,15 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
} else {
pending = p->migration_pending;
refcount_inc(&pending->refs);
+ /*
+ * Affinity has changed, but we've already installed a
+ * pending. migration_cpu_stop() *must* see this, else
+ * we risk a completion of the pending despite having a
+ * task on a disallowed CPU.
+ *
+ * Serialized by p->pi_lock, so this is safe.
+ */
+ pending->arg.dest_cpu = dest_cpu;
}
}
pending = p->migration_pending;