Re: [PATCH] net: skbuff: keep the page_pool fragment offset aligned in skb_pp_cow_data()

[Bruno Xavier <bfxavier@gmail.com>]

On Sun, Aug 30, 2026 at 09:23:27PM +0000, Fabricio Gava wrote:
> That version has already been sent, by Florian Schauer, the day before
> this patch -- "page_pool: keep frag_offset aligned for odd-sized requests",
> now at v2:

Thanks for linking the threads, I had not seen Florian's v1.

> xdp_copy_frags_from_zc() does the same, net/core/xdp.c:700-705:

I mispoke in my own notes on this one. I checked system_page_pool for
other consumers before sending and read it as having exactly one,
net/core/dev.c:5619. xdp.c:753 is the second. So fixing skb_pp_cow_data()
alone leaves the defect reachable through the zero-copy path.

Florian's patch is the right fix. Please drop this one.

On veth, drivers/net/veth.c:762 passes its own rq->page_pool rather than
the per-cpu one, so I don't think it widens the sharing. It widens where
the misaligning loop runs, which is the part your reading of the Fixes tag
gets at.

I have the reproducer and an A/B kernel harness here. Building v2 now,
numbers on Florian's thread.

Thanks,
Bruno