Re: [PATCH][v2] netfilter: use kvzalloc to allocate memory for hashtable

[Eric Dumazet]

On 07/24/2018 10:34 PM, Li RongQing wrote:
> nf_ct_alloc_hashtable is used to allocate memory for conntrack,
> NAT bysrc and expectation hashtable. Assuming 64k bucket size,
> which means 7th order page allocation, __get_free_pages, called
> by nf_ct_alloc_hashtable, will trigger the direct memory reclaim
> and stall for a long time, when system has lots of memory stress

...

>       sz = nr_slots * sizeof(struct hlist_nulls_head);
> -     hash = (void *)__get_free_pages(GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
> -                                     get_order(sz));
> -     if (!hash)
> -             hash = vzalloc(sz);
> +     hash = kvzalloc(sz, GFP_KERNEL);


You could remove the @sz computation and call 

hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL);

Thanks to kvmalloc_array() check, you also could remove the :

if (nr_slots > (UINT_MAX / sizeof(struct hlist_nulls_head)))
    return NULL;

That would remove a lot of stuff now we have proper helpers.