Tejun,
On 6/2/2016 10:39 PM, Tejun Heo wrote:
> On Thu, Jun 02, 2016 at 03:48:51PM +0800, Wang Sheng-Hui wrote:
>> +static int __init lru_init(void)
>> +{
>> + lru_add_drain_wq = alloc_workqueue("lru-add-drain",
>> + WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
> Why is it unbound?
Sorry, I just pasted from other wq create statement.
WQ_MEM_RECLAIM is the key. Will drop WQ_UNBOUND in new version patch.
>> + if (WARN(!lru_add_drain_wq,
>> + "Failed to create workqueue lru_add_drain_wq"))
>> + return -ENOMEM;
> I don't think we need an explicit warn here. Doesn't error return
> from an init function trigger boot failure anyway?
Will drop the warn and return -ENOMEM directly on failure.
>> + return 0;
>> +}
>> +early_initcall(lru_init);
>> +
>> void lru_add_drain_all(void)
>> {
>> static DEFINE_MUTEX(lock);
>> static struct cpumask has_work;
>> int cpu;
>>
>> + struct workqueue_struct *lru_wq = lru_add_drain_wq ?: system_wq;
>> +
>> + WARN_ONCE(!lru_add_drain_wq,
>> + "Use system_wq to do lru_add_drain_all()");
> Ditto. The system is crashing for sure. What's the point of this
> warning?
It's for above warn failure. Will crash instead of falling back to system_wq
>
> Thanks.
>
Thanks,
Sheng-Hui
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