Thread (6 messages) flat view 6 messages, 3 authors, 2017-01-20

Re: [PATCH net-next] mlx4: support __GFP_MEMALLOC for rx

From: Konstantin Khlebnikov <hidden>
Date: 2017-01-18 09:31:21
Also in: linux-mm

On 18.01.2017 07:14, Eric Dumazet wrote:
From: Eric Dumazet <edumazet@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.
quoted hunk ↗ jump to hunk
Note that this driver does not reuse pages (yet) so we do not have to
add anything else.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Konstantin Khlebnikov <redacted>
Cc: Tariq Toukan <redacted>
---
 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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