Re: [PATCH rdma-rc] RDMA/mlx5: Fix DevX umem page size truncation for pages >= 4G

[Jason Gunthorpe]

On Wed, Nov 04, 2026 at 12:07:47PM +0200, Leon Romanovsky wrote:

> Isn't this fix enough?
> https://patch.msgid.link/r/1-v1-88303e9e509f+f7-ib_umem_types_jgg@xxxxxxxxxx
> 15fe76e23615 ("RDMA/umem: Fix truncation for block sizes >= 4G")

No, the long AI generated commit message buried what the bug here is:

> > -static unsigned int devx_umem_find_best_pgsize(struct ib_umem *umem,
> > -					       unsigned long pgsz_bitmap)
> > +static unsigned long devx_umem_find_best_pgsize(struct ib_umem *umem,
> > +						unsigned long pgsz_bitmap)
> >  {

That 'int' is an integer truncation if the page size is > 4G. The
entire page size path from the core code has to be unsigned long if
the pgsz_bitmap is unsigned long.

Similar root cause of truncate, but different code.

Jason