In the case of an affinity change during a migrate_disable section, __set_cpus_allowed_ptr will not try to move the task from a CPU in which it cannot execute anymore.
So, after enabling migration, if the current task cannot execute in the current CPU anymore, migrate it away. Signed-off-by: Daniel Bristot de Oliveira <[email protected]> Cc: Luis Claudio R. Goncalves <[email protected]> Cc: Clark Williams <[email protected]> Cc: Luiz Capitulino <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: LKML <[email protected]> Cc: linux-rt-users <[email protected]> --- kernel/sched/core.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0396bf2..207bc85 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3462,6 +3462,34 @@ void migrate_enable(void) task_rq(p)->dl.dl_nr_migratory++; } + /* + * Check if the task can still run on this CPU. In the case of an + * affinity change during a migrate_disable section, + * __set_cpus_allowed_ptr will not try to move the task from a CPU + * that the task cannot execute anymore. + * + * So, if the current task cannot execute in the current CPU anymore, + * migrate it away. + */ + if (unlikely(!cpumask_test_cpu(task_cpu(p), &p->cpus_allowed))) { + const struct cpumask *cpu_mask = (p->flags & PF_KTHREAD) ? + cpu_online_mask : cpu_active_mask; + + int dest_cpu = cpumask_any_and(cpu_mask, &p->cpus_allowed); + struct migration_arg arg = {p, dest_cpu}; + + /* Need help from migration thread: drop lock and wait. */ + task_rq_unlock(rq, p, &rf); + unpin_current_cpu(); + preempt_enable(); + preempt_lazy_enable(); + + stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); + tlb_migrate_finish(p->mm); + + return; + } + task_rq_unlock(rq, p, &rf); unpin_current_cpu(); preempt_enable(); -- 2.9.4
