On Thu, May 22, 2025 at 4:54 PM Saeed Mahameed [off-list ref] wrote:

quoted

quoted

 static inline void
 mlx5e_copy_skb_header(struct mlx5e_rq *rq, struct sk_buff *skb,
-                     struct page *page, dma_addr_t addr,
+                     netmem_ref netmem, dma_addr_t addr,
                      int offset_from, int dma_offset, u32 headlen)
 {
-       const void *from = page_address(page) + offset_from;
+       const void *from = netmem_address(netmem) + offset_from;

I think this needs a check that netmem_address != NULL and safe error
handling in case it is? If the netmem is unreadable, netmem_address
will return NULL, and because you add offset_from to it, you can't
NULL check from as well.

Nope, this code path is not for GRO_HW, it is always safe to assume this is
not iov_netmem.

OK, thanks for checking. It may be worth it to add
DEBUG_NET_WARN_ON_ONCE(netmem_address(netmem)); in these places where
you're assuming the netmem is readable and has a valid address. It
would be a very subtle bug later on if someone moves the code or
something and suddenly you have unreadable netmem being funnelled
through these code paths. But up to you.

-- 
Thanks,
Mina