Messages in this thread | | | Date | Fri, 06 Jun 2014 08:39:31 -0400 | From | "Jason J. Herne" <> | Subject | Re: workqueue: WARN at at kernel/workqueue.c:2176 |
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On 06/05/2014 06:54 AM, Lai Jiangshan wrote: > The patch is not tested by Jason, I don't know whether the patch fix the problem. > The changlog including the "Reported-by:" and "Tested-by:" need to be updated > after it is proved. >
With this patch, my workload ran overnight without hitting the warning. This seems promising. I would like to run a day or two more before declaring success though. Just to be sure :).
> ------------ > > Subject: [PATCH] sched: migrate the waking tasks > > Current code skips to migrate the waking task silently when TTWU_QUEUE is enabled. > > When a task is waking, it is pending on the wake_list of the rq, but > it is not on queue (task->on_rq == 0). In this case, set_cpus_allowed_ptr() > and __migrate_task() will not migrate it due to it is not on queue. > > This behavior is incorrect, because the task had been already waken-up, it will > be running on the wrong CPU without correct placement until the next wake-up > or update for cpus_allowed. > > To fix this problem, we need to make the waking tasks on-queue (transfer > the waking tasks to running state) before migrate them. > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 268a45e..d05a5a1 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1474,20 +1474,24 @@ static int ttwu_remote(struct task_struct *p, int wake_flags) > } > > #ifdef CONFIG_SMP > -static void sched_ttwu_pending(void) > +static void sched_ttwu_pending_locked(struct rq *rq) > { > - struct rq *rq = this_rq(); > struct llist_node *llist = llist_del_all(&rq->wake_list); > struct task_struct *p; > > - raw_spin_lock(&rq->lock); > - > while (llist) { > p = llist_entry(llist, struct task_struct, wake_entry); > llist = llist_next(llist); > ttwu_do_activate(rq, p, 0); > } > +} > > +static void sched_ttwu_pending(void) > +{ > + struct rq *rq = this_rq(); > + > + raw_spin_lock(&rq->lock); > + sched_ttwu_pending_locked(rq); > raw_spin_unlock(&rq->lock); > } > > @@ -4530,6 +4534,11 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) > goto out; > > dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); > + > + /* Ensure it is on rq for migration if it is waking */ > + if (p->state == TASK_WAKING) > + sched_ttwu_pending_locked(rq); > + > if (p->on_rq) { > struct migration_arg arg = { p, dest_cpu }; > /* Need help from migration thread: drop lock and wait. */ > @@ -4576,6 +4585,10 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) > if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) > goto fail; > > + /* Ensure it is on rq for migration if it is waking */ > + if (p->state == TASK_WAKING) > + sched_ttwu_pending_locked(rq_src); > + > /* > * If we're not on a rq, the next wake-up will ensure we're > * placed properly. >
-- -- Jason J. Herne (jjherne@linux.vnet.ibm.com)
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