linux-kernel - Re: [PATCH 4/9] ila: simplify a strange allocation pattern

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Date:   Mon, 30 Jan 2017 16:21:08 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     David Rientjes <rientjes@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Al Viro <viro@...iv.linux.org.uk>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Tom Herbert <tom@...bertland.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH 4/9] ila: simplify a strange allocation pattern

On 01/30/2017 10:49 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
>
> alloc_ila_locks seemed to c&p from alloc_bucket_locks allocation
> pattern which is quite unusual. The default allocation size is 320 *
> sizeof(spinlock_t) which is sub page unless lockdep is enabled when the
> performance benefit is really questionable and not worth the subtle code
> IMHO. Also note that the context when we call ila_init_net (modprobe or
> a task creating a net namespace) has to be properly configured.
>
> Let's just simplify the code and use kvmalloc helper which is a
> transparent way to use kmalloc with vmalloc fallback.
>
> Cc: Tom Herbert <tom@...bertland.com>
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  net/ipv6/ila/ila_xlat.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/net/ipv6/ila/ila_xlat.c b/net/ipv6/ila/ila_xlat.c
> index af8f52ee7180..2fd5ca151dcf 100644
> --- a/net/ipv6/ila/ila_xlat.c
> +++ b/net/ipv6/ila/ila_xlat.c
> @@ -41,13 +41,7 @@ static int alloc_ila_locks(struct ila_net *ilan)
>  	size = roundup_pow_of_two(nr_pcpus * LOCKS_PER_CPU);
>
>  	if (sizeof(spinlock_t) != 0) {
> -#ifdef CONFIG_NUMA
> -		if (size * sizeof(spinlock_t) > PAGE_SIZE)
> -			ilan->locks = vmalloc(size * sizeof(spinlock_t));
> -		else
> -#endif
> -		ilan->locks = kmalloc_array(size, sizeof(spinlock_t),
> -					    GFP_KERNEL);
> +		ilan->locks = kvmalloc(size * sizeof(spinlock_t), GFP_KERNEL);
>  		if (!ilan->locks)
>  			return -ENOMEM;
>  		for (i = 0; i < size; i++)
>