lkml.org 
[lkml]   [2009]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: -next: Nov 12 - kernel BUG at kernel/sched.c:7359!
    Peter Zijlstra wrote:
    > Well, it boots for me, but then, I've not been able to reproduce any
    > issues anyway :/
    >
    > /me goes try a PREEMPT=n kernel, since that is what Mike reports boot
    > funnies with..
    >
    > Full running diff against -tip:
    >
    Peter i still can recreate this issue with today's next(20091123).
    Looks like the following patch haven't been merged yet.

    Thanks
    -Sachin

    > ---
    > diff --git a/kernel/sched.c b/kernel/sched.c
    > index 1f2e99d..7089063 100644
    > --- a/kernel/sched.c
    > +++ b/kernel/sched.c
    > @@ -2374,17 +2374,24 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
    > if (task_contributes_to_load(p))
    > rq->nr_uninterruptible--;
    > p->state = TASK_WAKING;
    > - task_rq_unlock(rq, &flags);
    > + __task_rq_unlock(rq);
    >
    > +again:
    > cpu = p->sched_class->select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
    > + if (!cpu_online(cpu))
    > + cpu = cpumask_any_and(&p->cpus_allowed, cpu_online_mask);
    > + if (cpu >= nr_cpu_ids) {
    > + printk(KERN_ERR "Breaking affinity on %d/%s\n", p->pid, p->comm);
    > + cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
    > + goto again;
    > + }
    > +
    > if (cpu != orig_cpu) {
    > - local_irq_save(flags);
    > rq = cpu_rq(cpu);
    > update_rq_clock(rq);
    > set_task_cpu(p, cpu);
    > - local_irq_restore(flags);
    > }
    > - rq = task_rq_lock(p, &flags);
    > + rq = __task_rq_lock(p);
    >
    > WARN_ON(p->state != TASK_WAKING);
    > cpu = task_cpu(p);
    > @@ -7620,6 +7627,8 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
    > unsigned long flags;
    > struct rq *rq;
    >
    > + printk(KERN_ERR "migration call\n");
    > +
    > switch (action) {
    >
    > case CPU_UP_PREPARE:
    > @@ -9186,6 +9195,8 @@ int __init sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
    > static int update_sched_domains(struct notifier_block *nfb,
    > unsigned long action, void *hcpu)
    > {
    > + printk(KERN_ERR "update_sched_domains\n");
    > +
    > switch (action) {
    > case CPU_ONLINE:
    > case CPU_ONLINE_FROZEN:
    > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
    > index 5488a5d..0ff21af 100644
    > --- a/kernel/sched_fair.c
    > +++ b/kernel/sched_fair.c
    > @@ -1345,6 +1345,37 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
    > }
    >
    > /*
    > + * Try and locate an idle CPU in the sched_domain.
    > + */
    > +static int
    > +select_idle_sibling(struct task_struct *p, struct sched_domain *sd, int target)
    > +{
    > + int cpu = smp_processor_id();
    > + int prev_cpu = task_cpu(p);
    > + int i;
    > +
    > + /*
    > + * If this domain spans both cpu and prev_cpu (see the SD_WAKE_AFFINE
    > + * test in select_task_rq_fair) and the prev_cpu is idle then that's
    > + * always a better target than the current cpu.
    > + */
    > + if (target == cpu && !cpu_rq(prev_cpu)->cfs.nr_running)
    > + return prev_cpu;
    > +
    > + /*
    > + * Otherwise, iterate the domain and find an elegible idle cpu.
    > + */
    > + for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) {
    > + if (!cpu_rq(i)->cfs.nr_running) {
    > + target = i;
    > + break;
    > + }
    > + }
    > +
    > + return target;
    > +}
    > +
    > +/*
    > * sched_balance_self: balance the current task (running on cpu) in domains
    > * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
    > * SD_BALANCE_EXEC.
    > @@ -1398,37 +1429,34 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
    > want_sd = 0;
    > }
    >
    > - if (want_affine && (tmp->flags & SD_WAKE_AFFINE)) {
    > - int candidate = -1, i;
    > + /*
    > + * While iterating the domains looking for a spanning
    > + * WAKE_AFFINE domain, adjust the affine target to any idle cpu
    > + * in cache sharing domains along the way.
    > + */
    > + if (want_affine) {
    > + int target = -1;
    >
    > + /*
    > + * If both cpu and prev_cpu are part of this domain,
    > + * cpu is a valid SD_WAKE_AFFINE target.
    > + */
    > if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp)))
    > - candidate = cpu;
    > + target = cpu;
    >
    > /*
    > - * Check for an idle shared cache.
    > + * If there's an idle sibling in this domain, make that
    > + * the wake_affine target instead of the current cpu.
    > */
    > - if (tmp->flags & SD_PREFER_SIBLING) {
    > - if (candidate == cpu) {
    > - if (!cpu_rq(prev_cpu)->cfs.nr_running)
    > - candidate = prev_cpu;
    > - }
    > + if (tmp->flags & SD_PREFER_SIBLING)
    > + target = select_idle_sibling(p, tmp, target);
    >
    > - if (candidate == -1 || candidate == cpu) {
    > - for_each_cpu(i, sched_domain_span(tmp)) {
    > - if (!cpumask_test_cpu(i, &p->cpus_allowed))
    > - continue;
    > - if (!cpu_rq(i)->cfs.nr_running) {
    > - candidate = i;
    > - break;
    > - }
    > - }
    > + if (target >= 0) {
    > + if (tmp->flags & SD_WAKE_AFFINE) {
    > + affine_sd = tmp;
    > + want_affine = 0;
    > }
    > - }
    > -
    > - if (candidate >= 0) {
    > - affine_sd = tmp;
    > - want_affine = 0;
    > - cpu = candidate;
    > + cpu = target;
    > }
    > }
    >
    >
    >
    >


    --

    ---------------------------------
    Sachin Sant
    IBM Linux Technology Center
    India Systems and Technology Labs
    Bangalore, India
    ---------------------------------



    \
     
     \ /
      Last update: 2009-11-23 10:57    [W:0.033 / U:0.064 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site