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

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

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 <eduma...@google.com>
Cc: Tariq Toukan <tar...@mellanox.com>
Cc: Saeed Mahameed <sae...@mellanox.com>
---
 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 
0e2fb3ed1790900ccdc0bbbef8bc5c33267df092..ce46409bde2736ea4d1246ca97855098f052f271
 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;