Re: Excessive memory usage when infiniband config is enabled

[Leon Romanovsky <leon@kernel.org>]

On Mon, May 06, 2024 at 05:15:55PM +0200, Brian Baboch wrote:
> Hello,
> 
> 
> We discovered that the CONFIG_INFINIBAND_IRDMA configuration option in the
> linux kernel is causing excessive memory usage on idle mode on specific
> servers like the DELL VEP4600
> (https://www.dell.com/en-us/shop/ipovw/virtual-edge-platform-4600.
> 
> By default we were using Debian's linux-image-6.1.0-13-amd64 which is the
> stable 6.1.55-1 amd64, we then compiled the kernel again with the same
> config file from the stable 6.1.55 tag and had the same problem. We were
> able to resolve the memory problem by removing the `CONFIG_INFINIBAND_IRDMA`
> option from the kernel config.
> 
> The tag used to reproduce the problem is v6.1.55.
> adding the following config `CONFIG_INFINIBAND_IRDMA=m` causes the excessive
> memory usage to go from 1.4Gb to 7Gb.

Hi Brian,

Why do you think that this is a bug?
DELL VEP4600 supports RDMA, so by enabling CONFIG_INFINIBAND_IRDMA, you
compiled RDMA support for Intel NIC.
https://dl.dell.com/topicspdf/vep4600_tech_guide_en-us.pdf

You can unload irdma.ko module and restore memory footprint.

Thanks