6.15-stable review patch. If anyone has any objections, please let me know.
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From: Jakub Kicinski kuba@kernel.org
[ Upstream commit e407fceeaf1b2959892b4fc9b584843d3f2bfc05 ]
Alex added page bias of LONG_MAX, which is admittedly quite a clever way of catching overflows of the pp ref count. The page pool code was "optimized" to leave the ref at 1 for freed pages so it can't catch basic bugs by itself any more. (Something we should probably address under DEBUG_NET...)
Unfortunately for fbnic since commit f7dc3248dcfb ("skbuff: Optimization of SKB coalescing for page pool") core _may_ actually take two extra pp refcounts, if one of them is returned before driver gives up the bias the ret < 0 check in page_pool_unref_netmem() will trigger.
While at it add a FBNIC_ to the name of the driver constant.
Fixes: 0cb4c0a13723 ("eth: fbnic: Implement Rx queue alloc/start/stop/free") Link: https://patch.msgid.link/20250801170754.2439577-1-kuba@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/meta/fbnic/fbnic_txrx.c | 4 ++-- drivers/net/ethernet/meta/fbnic/fbnic_txrx.h | 6 ++---- 2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c index ac11389a764c..f9543d03485f 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c +++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c @@ -661,8 +661,8 @@ static void fbnic_page_pool_init(struct fbnic_ring *ring, unsigned int idx, { struct fbnic_rx_buf *rx_buf = &ring->rx_buf[idx];
- page_pool_fragment_page(page, PAGECNT_BIAS_MAX); - rx_buf->pagecnt_bias = PAGECNT_BIAS_MAX; + page_pool_fragment_page(page, FBNIC_PAGECNT_BIAS_MAX); + rx_buf->pagecnt_bias = FBNIC_PAGECNT_BIAS_MAX; rx_buf->page = page; }
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h index f46616af41ea..37b4dadbfc6c 100644 --- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h +++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h @@ -91,10 +91,8 @@ struct fbnic_queue_stats { struct u64_stats_sync syncp; };
-/* Pagecnt bias is long max to reserve the last bit to catch overflow - * cases where if we overcharge the bias it will flip over to be negative. - */ -#define PAGECNT_BIAS_MAX LONG_MAX +#define FBNIC_PAGECNT_BIAS_MAX PAGE_SIZE + struct fbnic_rx_buf { struct page *page; long pagecnt_bias;