On 7/22/20 1:49 AM, Baoquan He wrote:
> On 07/20/20 at 05:38pm, Mike Kravetz wrote:
>>> +   if (count != h->max_huge_pages) {
>>> +           char buf[32];
>>> +
>>> +           string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
>>> +           pr_warn("HugeTLB: %s %lu of page size %s failed. Only %s %lu 
>>> hugepages.\n",
>>> +                   count > old_max ? "increasing" : "decreasing",
>>> +                   abs(count - old_max), buf,
>>> +                   count > old_max ? "increased" : "decreased",
>>> +                   abs(old_max - h->max_huge_pages));
>>> +   }
>>>     spin_unlock(&hugetlb_lock);
>>
>> I would prefer if we drop the lock before logging the message.  That would
>> involve grabbing the value of h->max_huge_pages before dropping the lock.
> 
> Do you think the below change is OK to you to move the message logging
> after lock dropping? If yes, I will repost with updated patches.
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6a9b7556ce5b..b5aa32a13569 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2661,7 +2661,7 @@ static int adjust_pool_surplus(struct hstate *h, 
> nodemask_t *nodes_allowed,
>  static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
>                             nodemask_t *nodes_allowed)
>  {
> -     unsigned long min_count, ret, old_max;
> +     unsigned long min_count, ret, old_max, new_max;
>       NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);
>  
>       /*
> @@ -2780,7 +2780,10 @@ static int set_max_huge_pages(struct hstate *h, 
> unsigned long count, int nid,
>       }
>  out:
>       h->max_huge_pages = persistent_huge_pages(h);
> -     if (count != h->max_huge_pages) {
> +     new_max = h->max_huge_pages;
> +     spin_unlock(&hugetlb_lock);
> +
> +     if (count != new_max) {
>               char buf[32];
>  
>               string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
> @@ -2788,9 +2791,8 @@ static int set_max_huge_pages(struct hstate *h, 
> unsigned long count, int nid,
>                       count > old_max ? "increasing" : "decreasing",
>                       abs(count - old_max), buf,
>                       count > old_max ? "increased" : "decreased",
> -                     abs(old_max - h->max_huge_pages));
> +                     abs(old_max - new_max));
>       }
> -     spin_unlock(&hugetlb_lock);
>  
>       NODEMASK_FREE(node_alloc_noretry);

Yes, that looks better.  Thank you.

-- 
Mike Kravetz

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