netdev - Re: [PATCH net-next] net/smc: Use kvzalloc for allocating smc_link

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Date:   Thu, 20 Jan 2022 15:50:26 +0100
From:   Karsten Graul <kgraul@...ux.ibm.com>
To:     Tony Lu <tonylu@...ux.alibaba.com>
Cc:     kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH net-next] net/smc: Use kvzalloc for allocating
 smc_link_group

On 20/01/2022 15:09, Tony Lu wrote:
> When analyzed memory usage of SMC, we found that the size of struct
> smc_link_group is 16048 bytes, which is too big for a busy machine to
> allocate contiguous memory. Using kvzalloc instead that falls back to
> vmalloc if there has not enough contiguous memory.

I am wondering where the needed contiguous memory for the required RMB buffers should come from when 
you don't even get enough storage for the initial link group?

The idea is that when the system is so low on contiguous memory then a link group creation should fail 
early, because most of the later buffer allocations will also fail then later.