Subject: [PATCH 24/32] net/mlx5e: Do not recycle pages from emergency reserve

From: Eric Dumazet <[email-masked]>
Date: Wed, 18 Jan 2017 23:03:08 -0800

[ Upstream commit e048fc50d7bde23136e098e04a324d7e3404408d ]

A driver using dev_alloc_page() must not reuse a page allocated from
emergency memory reserve.

Otherwise all packets using this page will be immediately dropped,
unless for very specific sockets having SOCK_MEMALLOC bit set.

This issue might be hard to debug, because only a fraction of received
packets would be dropped.

Fixes: 4415a0319f92 ("net/mlx5e: Implement RX mapped page cache for page recycle")
Signed-off-by: Eric Dumazet <[email-masked]>
Cc: Tariq Toukan <[email-masked]>
Cc: Saeed Mahameed <[email-masked]>
Acked-by: Saeed Mahameed <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 33495d8..e7b2158 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -193,6 +193,9 @@ static inline bool mlx5e_rx_cache_put(struct mlx5e_rq *rq,
 		return false;
 	}
 
+	if (unlikely(page_is_pfmemalloc(dma_info->page)))
+		return false;
+
 	cache->page_cache[cache->tail] = *dma_info;
 	cache->tail = tail_next;
 	return true;
-- 
2.4.11