netdev - Re: [RFC] tcp md5 use of alloc

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Date:	Thu, 23 Oct 2014 19:17:47 +0300
From:	Crestez Dan Leonard <cdleonard@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Jonathan Toppins <jtoppins@...ulusnetworks.com>,
	David Ahern <dsahern@...il.com>, netdev@...r.kernel.org
Subject: Re: [RFC] tcp md5 use of alloc_percpu

On 10/23/2014 05:43 PM, Eric Dumazet wrote:
> On Thu, 2014-10-23 at 06:21 -0700, Eric Dumazet wrote:
>> On Thu, 2014-10-23 at 02:58 -0400, Jonathan Toppins wrote:
>>
>>>> +		if (!pool) {
>>>> +			pool = kzalloc_node(sizeof(*pool), GFP_KERNEL,
>>> GFP_DMA | GFP_KERNEL
>>> This memory will possibly be used in a DMA correct? (thinking crypto
>>> hardware offload)
>>
>> I am not sure this is the case, but this certainly can be added.
>>
> 
> Yes, this is not the case.
> 
> 
> The real problem is because sg_set_buf() does the following :
> sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
> 
> So it assumes a memory range is not spanning multiple pages.
Doesn't virt_to_page also assume that the memory is not from vmalloc?

Making this portable would require checking if is_vmalloc_addr and doing
vmalloc_to_page instead. Easier to just kmalloc instead.

Regards,
Leonard
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