On 18.01.2017 07:14, Eric Dumazet wrote:
From: Eric Dumazet <eduma...@google.com>

Commit 04aeb56a1732 ("net/mlx4_en: allocate non 0-order pages for RX
ring with __GFP_NOMEMALLOC") added code that appears to be not needed at
that time, since mlx4 never used __GFP_MEMALLOC allocations anyway.

As using memory reserves is a must in some situations (swap over NFS or
iSCSI), this patch adds this flag.

AFAIK __GFP_MEMALLOC is used for TX, not for RX: for allocations which are 
required by memory reclaimer to free some pages.

Allocation RX buffers with __GFP_MEMALLOC is a straight way to depleting all 
reserves by flood from network.


Note that this driver does not reuse pages (yet) so we do not have to
add anything else.

Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Konstantin Khlebnikov <khlebni...@yandex-team.ru>
Cc: Tariq Toukan <tar...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c 
b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 
eac527e25ec902c2a586e9952272b9e8e599e2c8..e362f99334d03c0df4d88320977670015870dd9c
 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -706,7 +706,8 @@ static bool mlx4_en_refill_rx_buffers(struct mlx4_en_priv 
*priv,
        do {
                if (mlx4_en_prepare_rx_desc(priv, ring,
                                            ring->prod & ring->size_mask,
-                                           GFP_ATOMIC | __GFP_COLD))
+                                           GFP_ATOMIC | __GFP_COLD |
+                                           __GFP_MEMALLOC))
                        break;
                ring->prod++;
        } while (--missing);




--
Konstantin

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