Re: [PATCH] IB/cache: Check GID table references before attempting deletion

[Jason Gunthorpe <jgg@ziepe.ca>]

On Mon, May 18, 2026 at 10:36:57AM +0800, Chenguang Zhao wrote:
>  After calling kref_put(&entry->kref) in put_gid_entry_locked(), the reference count does not drop to zero.
> This is because the GID entry is still held by NFS via call paths such as
> cma_acquire_dev_by_src_ip() -> cma_validate_port() -> rdma_find_gid_by_port() -> get_gid_entry().
> Consequently, the GID entry cannot be freed. Meanwhile, the corresponding GID has already been removed 
> from hardware/driver layer via ib_dev->ops.del_gid(). Subsequent ifup attempts keep inserting new entries
>  into the GID table, and repeated cycles of ifdown and ifup eventually exhaust the entire GID table space.

This is a bug in NFS/etc to hold on to GID entries forever.

> To resolve this issue, we add a check before removing GID entries in the driver. We forbid the deletion
> operation if entry->kref is not equal to 1 (the initial reference count value). With this constraint, existing 
> valid entries will be detected and reused after ifup, avoiding redundant insertion into the GID table.

Definately no, you cannot keep GID entries alive that are removed from
the netdev.

Jason