> -----Original Message-----
> From: Pavel Begunkov <[email protected]>
> Sent: Wednesday, December 17, 2025 2:16 PM
> To: Loktionov, Aleksandr <[email protected]>; Byungchul
> Park <[email protected]>; [email protected]; [email protected]
> Cc: [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; Nguyen, Anthony L
> <[email protected]>; Kitszel, Przemyslaw
> <[email protected]>; [email protected];
> [email protected]; [email protected]; [email protected]; intel-
> [email protected]
> Subject: Re: [Intel-wired-lan] [PATCH net-next] ice: access @pp
> through netmem_desc instead of page
>
> On 12/17/25 11:46, Loktionov, Aleksandr wrote:
> >
> >
> >> -----Original Message-----
> >> From: Intel-wired-lan <[email protected]> On
> Behalf
> >> Of Byungchul Park
> >> Sent: Tuesday, December 16, 2025 5:07 AM
> >> To: [email protected]; [email protected]
> >> Cc: [email protected]; [email protected];
> >> [email protected]; [email protected]; [email protected];
> >> [email protected]; [email protected]; [email protected];
> >> Nguyen, Anthony L <[email protected]>; Kitszel, Przemyslaw
> >> <[email protected]>; [email protected];
> >> [email protected]; [email protected]; [email protected]; intel-
> >> [email protected]
> >> Subject: [Intel-wired-lan] [PATCH net-next] ice: access @pp through
> >> netmem_desc instead of page
> >>
> >> To eliminate the use of struct page in page pool, the page pool
> users
> >> should use netmem descriptor and APIs instead.
> >>
> >> Make ice driver access @pp through netmem_desc instead of page.
> >>
> > Please add test info: HW/ASIC + PF/VF/SR-IOV, kernel version/branch,
> exact repro steps, before/after results (expected vs. observed).
> >
> >> Signed-off-by: Byungchul Park <[email protected]>
> >> ---
> >> drivers/net/ethernet/intel/ice/ice_ethtool.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c
> >> b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> >> index 969d4f8f9c02..ae8a4e35cb10 100644
> >> --- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
> >> +++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> >> @@ -1251,7 +1251,7 @@ static int ice_lbtest_receive_frames(struct
> >> ice_rx_ring *rx_ring)
> >> rx_buf = &rx_ring->rx_fqes[i];
> >> page = __netmem_to_page(rx_buf->netmem);
> >> received_buf = page_address(page) + rx_buf->offset +
> >> - page->pp->p.offset;
> >> + pp_page_to_nmdesc(page)->pp->p.offset;
> > If rx_buf->netmem is not backed by a page pool (e.g., fallback
> allocation), pp will be NULL and this dereferences NULL.
> > I think the loopback test runs in a controlled environment, but the
> code must verify pp is valid before dereferencing.
> > Isn't it?
>
> Considering "page->pp->p.offset" poking into the pool, if that can
> happen it's a pre-existing problem, which should be fixed first.
>
> --
> Pavel Begunkov
Good day, Hi Byungchul, Pavel,
Thanks for pushing the driver toward netmem — I fully support removing direct
struct page accesses from the networking stack.
Regarding this change in ice_lbtest_receive_frames():
received_buf = page_address(page) + rx_buf->offset +
pp_page_to_nmdesc(page)->pp->p.offset;
Pavel, you're right that if page->pp could be NULL, it's a pre-existing bug
that should be fixed.
However, looking at the loopback test path, I'm concerned this code doesn't
handle non-page-pool allocations safely.
The netmem model explicitly allows for buffers that aren't page-pool backed.
While the loopback test likely runs in a controlled environment, the code
should verify pp is valid before dereferencing,
or use the netmem helpers that handle this gracefully:
struct netmem_desc *ndesc = __netmem_to_nmdesc(rx_buf->netmem);
void *addr = netmem_address(rx_buf->netmem);
struct page_pool *pp;
if (!addr)
continue; /* unreadable netmem */
pp = __netmem_get_pp(ndesc);
received_buf = addr + rx_buf->offset + (pp ? pp->p.offset : 0);
Alternatively, guard the existing code with page_pool_page_is_pp(page) before
calling pp_page_to_nmdesc().
This would complete the netmem conversion while fixing the unsafe dereference,
aligning with Matthew's earlier suggestion to use descriptor/address accessors.
Also, please add test details to the commit message:
HW/ASIC (e.g., E810/E823)
PF vs VF, SR-IOV configuration
Kernel tree/commit (net-next @ <sha>)
Repro steps: ethtool -t $dev offline
Before/after behavior
Happy to review v2 with these changes.
Best regards,
Alex
