netdev - RE: [PATCH bpf-next] mm: implement no-MMU variant of vmalloc_user_node

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Date:   Mon, 25 Nov 2019 12:36:05 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Andrii Nakryiko <andriin@...com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, ast@...com, daniel@...earbox.net
Cc:     andrii.nakryiko@...il.com, kernel-team@...com,
        Andrii Nakryiko <andriin@...com>,
        Johannes Weiner <hannes@...xchg.org>
Subject: RE: [PATCH bpf-next] mm: implement no-MMU variant of
 vmalloc_user_node_flags

Andrii Nakryiko wrote:
> To fix build with !CONFIG_MMU, implement it for no-MMU configurations as well.
> 
> Cc: Johannes Weiner <hannes@...xchg.org>
> Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
> Reported-by: kbuild test robot <lkp@...el.com>
> Signed-off-by: Andrii Nakryiko <andriin@...com>
> ---
>  mm/nommu.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 99b7ec318824..7de592058ab4 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -155,11 +155,11 @@ void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags)
>  	return __vmalloc(size, flags, PAGE_KERNEL);
>  }
>  
> -void *vmalloc_user(unsigned long size)
> +static void *__vmalloc_user_flags(unsigned long size, gfp_t flags)
>  {
>  	void *ret;
>  
> -	ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
> +	ret = __vmalloc(size, flags, PAGE_KERNEL);
>  	if (ret) {
>  		struct vm_area_struct *vma;
>  
> @@ -172,8 +172,19 @@ void *vmalloc_user(unsigned long size)
>  
>  	return ret;
>  }
> +
> +void *vmalloc_user(unsigned long size)
> +{
> +	return __vmalloc_user_flags(size, GFP_KERNEL | __GFP_ZERO);
> +}
>  EXPORT_SYMBOL(vmalloc_user);
>  
> +void *vmalloc_user_node_flags(unsigned long size, int node, gfp_t flags)
> +{
> +	return __vmalloc_user_flags(size, flags | __GFP_ZERO);
> +}
> +EXPORT_SYMBOL(vmalloc_user_node_flags);
> +

Hi Andrii, my first reaction was that it seemed not ideal to just ignore
the node value like this but everything I came up with was uglier. I
guess only user is BPF at the moment so it should be fine.

Acked-by: John Fastabend <john.fastabend@...il.com>