Re: [PATCH v2] RDMA/srpt: Make slab cache names unique

[Leon Romanovsky <leonro@nvidia.com>]

On Mon, Oct 07, 2024 at 01:37:26PM -0700, Bart Van Assche wrote:
> Since commit 4c39529663b9 ("slab: Warn on duplicate cache names when
> DEBUG_VM=y"), slab complains about duplicate cache names. Hence this
> patch. The approach is as follows:
> - Maintain an xarray with the slab size as index and a reference count
>   and a kmem_cache pointer as contents. Use srpt-${slab_size} as kmem
>   cache name.
> - Use 512-byte alignment for all slabs instead of only for some of the
>   slabs.
> - Increment the reference count instead of calling kmem_cache_create().
> - Decrement the reference count instead of calling kmem_cache_destroy().
> 
> Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Closes: https://lore.kernel.org/linux-block/xpe6bea7rakpyoyfvspvin2dsozjmjtjktpph7rep3h25tv7fb@ooz4cu5z6bq6/
> Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Fixes: 5dabcd0456d7 ("RDMA/srpt: Add support for immediate data")
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/infiniband/ulp/srpt/ib_srpt.c | 79 +++++++++++++++++++++++----
>  1 file changed, 67 insertions(+), 12 deletions(-)
> 
> Changes compared to v1:
>  - Instead of using an ida to make slab names unique, maintain an xarray
>    with the slab size as index and the slab pointer and a reference count as
>    contents.

<...>

> +	if (IS_ERR(xa_store(&srpt_memory_caches, object_size, e, GFP_KERNEL)))

xarray API needs to be checked with xa_is_err() instead of IS_ERR().

Thanks