Subject: Re: [PATCH net] bpf: fix allocation warnings in bpf maps and integer overflow

From: Daniel Borkmann <[email-masked]>
Date: Mon, 30 Nov 2015 15:13:47 +0100

On 11/30/2015 02:57 PM, Dmitry Vyukov wrote:
...
> kamlloc produces a WARNING if you try to allocate more than it ever
> possibly can (KMALLOC_SHIFT_MAX).

Sure, I understand that.

The kzalloc() in array_map_alloc() is however with __GFP_NOWARN flag already.
The warning only triggers in mm if:

   WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));

Your test case is using ca.map_type = 1, which is BPF_MAP_TYPE_HASH. So on
update you're triggering the kmalloc() in htab_map_update_elem().

I'm just asking about the added change in array map.

Thanks,
Daniel