[Devel] [PATCH rh7 2/2] net/sock: teach sock_kmalloc() to call kvmalloc() when possible

[Andrey Ryabinin]

On 03/21/2018 02:11 PM, Konstantin Khorenko wrote:
> sock_setsockopt()
>  sk_attach_filter()
>   sock_kmalloc()
> 
> Memory size to be allocated depends on the number of rules provided by
> userspace, but not more than net.core.optmem_max (20480 by default),
> which still allows to allocate 3rd order pages via kmalloc() =>
> it's better to substitute it with kvmalloc().
> 
> But sock_kmalloc() can be called with GFP_ATOMIC from some places,
> so we cannot unconditionally call kvmalloc() instead of kmalloc().
> 
> Hopefully sk_attach_filter() calls sock_kmalloc() with GFP_KERNEL,
> so kvmalloc() can be used there.
> 
> => use kvmalloc_check() which calls kvmalloc() if it's allowed
> by provided flags.
> 

seems fishy. What we are going to do when we GFP_ATOMIC will ask for 3 order?

> https://jira.sw.ru/browse/PSBM-82593
> 
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
> ---
>  net/core/sock.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/sock.c b/net/core/sock.c
> index b4abbbf35797..5d2016807042 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -1707,7 +1707,7 @@ void *sock_kmalloc(struct sock *sk, int size, gfp_t priority)
>  		 * might sleep.
>  		 */
>  		atomic_add(size, &sk->sk_omem_alloc);
> -		mem = kmalloc(size, priority);
> +		mem = kvmalloc_check(size, priority);
>  		if (mem)
>  			return mem;
>  		atomic_sub(size, &sk->sk_omem_alloc);
> @@ -1721,7 +1721,7 @@ EXPORT_SYMBOL(sock_kmalloc);
>   */
>  void sock_kfree_s(struct sock *sk, void *mem, int size)
>  {
> -	kfree(mem);
> +	kvfree(mem);
>  	atomic_sub(size, &sk->sk_omem_alloc);
>  }
>  EXPORT_SYMBOL(sock_kfree_s);
>