lkml.org 
[lkml]   [2014]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [tip:sched/core] sched/numa: Move task_numa_free() to __put_task_struct()


On Mon, 7 Apr 2014, Mike Galbraith wrote:

> On Mon, 2014-04-07 at 10:16 +0200, Peter Zijlstra wrote:
>> On Mon, Apr 07, 2014 at 09:30:30AM +0200, Mike Galbraith wrote:
>>> - double_lock(&my_grp->lock, &grp->lock);
>>> + BUG_ON(irqs_disabled());
>>> + double_lock_irq(&my_grp->lock, &grp->lock);
>>
>> So either make this:
>>
>> local_irq_disable();
>> double_lock();
>>
>> or
>>
>>>
>>> for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
>>> my_grp->faults[i] -= p->numa_faults_memory[i];
>>> @@ -1692,6 +1693,7 @@ static void task_numa_group(struct task_
>>>
>>> spin_unlock(&my_grp->lock);
>>> spin_unlock(&grp->lock);
>>> + local_irq_enable();
>>
>> use:
>> spin_unlock()
>> spin_unlock_irq()
>>
>> or so, but this imbalance is making my itch :-)
>
> sched, numa: fix task_numa_free() lockdep splat
>
> Sasha reports that lockdep claims 156654f491dd8d52687a5fbe1637f472a52ce75b made
> numa_group.lock interrupt unsafe. While I don't see how that could be given the
> commit in question moved task_numa_free() from one irq enabled region to another,
> the below does make both gripes and lockups upon gripe with numa=fake=4 go away.
>

Hi

I Am hitting this bug quite frequently. I do not see the problem after applying
this patch.

Thanks

Tested-by: Govindarajulu Varadarajan <govindx7c6@gmail.com>

> Reported-by: Sasha Levin <sasha.levin@oracle.com>
> Signed-off-by: Mike Galbraith <bitbucket@online.de>
> ---
> kernel/sched/fair.c | 13 +++++++------
> kernel/sched/sched.h | 9 +++++++++
> 2 files changed, 16 insertions(+), 6 deletions(-)
>
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1497,7 +1497,7 @@ static void task_numa_placement(struct t
> /* If the task is part of a group prevent parallel updates to group stats */
> if (p->numa_group) {
> group_lock = &p->numa_group->lock;
> - spin_lock(group_lock);
> + spin_lock_irq(group_lock);
> }
>
> /* Find the node with the highest number of faults */
> @@ -1572,7 +1572,7 @@ static void task_numa_placement(struct t
> }
> }
>
> - spin_unlock(group_lock);
> + spin_unlock_irq(group_lock);
> }
>
> /* Preferred node as the node with the most faults */
> @@ -1677,7 +1677,8 @@ static void task_numa_group(struct task_
> if (!join)
> return;
>
> - double_lock(&my_grp->lock, &grp->lock);
> + BUG_ON(irqs_disabled());
> + double_lock_irq(&my_grp->lock, &grp->lock);
>
> for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
> my_grp->faults[i] -= p->numa_faults_memory[i];
> @@ -1691,7 +1692,7 @@ static void task_numa_group(struct task_
> grp->nr_tasks++;
>
> spin_unlock(&my_grp->lock);
> - spin_unlock(&grp->lock);
> + spin_unlock_irq(&grp->lock);
>
> rcu_assign_pointer(p->numa_group, grp);
>
> @@ -1710,14 +1711,14 @@ void task_numa_free(struct task_struct *
> void *numa_faults = p->numa_faults_memory;
>
> if (grp) {
> - spin_lock(&grp->lock);
> + spin_lock_irq(&grp->lock);
> for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
> grp->faults[i] -= p->numa_faults_memory[i];
> grp->total_faults -= p->total_numa_faults;
>
> list_del(&p->numa_entry);
> grp->nr_tasks--;
> - spin_unlock(&grp->lock);
> + spin_unlock_irq(&grp->lock);
> rcu_assign_pointer(p->numa_group, NULL);
> put_numa_group(grp);
> }
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1388,6 +1388,15 @@ static inline void double_lock(spinlock_
> spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
> }
>
> +static inline void double_lock_irq(spinlock_t *l1, spinlock_t *l2)
> +{
> + if (l1 > l2)
> + swap(l1, l2);
> +
> + spin_lock_irq(l1);
> + spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
> +}
> +
> static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2)
> {
> if (l1 > l2)
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>


\
 
 \ /
  Last update: 2014-04-13 23:21    [W:0.059 / U:0.452 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site