[PATCH net] gianfar: Do not reuse pages from emergency reserve

[PATCH net] gianfar: Do not reuse pages from emergency reserve

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

A driver using dev_alloc_page() must not reuse a page that had to
use 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 the RX
ring buffer would suffer from drops.

Fixes: 75354148ce69 ("gianfar: Add paged allocation and Rx S/G")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Claudiu Manoil <claudiu.manoil@freescale.com>
---
 drivers/net/ethernet/freescale/gianfar.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index a6e7afa878befd1abe00404b2cd4becfa174d103..c1b6716679208a69bc66f017a68e5b6e35c60064 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2948,7 +2948,7 @@ static bool gfar_add_rx_frag(struct gfar_rx_buff *rxb, u32 lstatus,
 	}
 
 	/* try reuse page */
-	if (unlikely(page_count(page) != 1))
+	if (unlikely(page_count(page) != 1 || page_is_pfmemalloc(page)))
 		return false;
 
 	/* change offset to the other half */

RE: [PATCH net] gianfar: Do not reuse pages from emergency reserve

[Claudiu Manoil]

>-----Original Message-----
>From: Eric Dumazet [mailto:eric.dumazet@gmail.com]
>Sent: Thursday, January 19, 2017 5:45 AM
>To: David Miller <davem@davemloft.net>
>Cc: netdev <netdev@vger.kernel.org>; Claudiu Manoil
><claudiu.manoil@freescale.com>
>Subject: [PATCH net] gianfar: Do not reuse pages from emergency reserve
>
>From: Eric Dumazet <edumazet@google.com>
>
>A driver using dev_alloc_page() must not reuse a page that had to
>use 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 the RX
>ring buffer would suffer from drops.
>
>Fixes: 75354148ce69 ("gianfar: Add paged allocation and Rx S/G")
>Signed-off-by: Eric Dumazet <edumazet@google.com>
>Cc: Claudiu Manoil <claudiu.manoil@freescale.com>

Thanks.

Acked-by: Claudiu Manoil <claudiu.manoil@nxp.com>

Re: [PATCH net] gianfar: Do not reuse pages from emergency reserve

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 18 Jan 2017 19:44:42 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> A driver using dev_alloc_page() must not reuse a page that had to
> use 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 the RX
> ring buffer would suffer from drops.
> 
> Fixes: 75354148ce69 ("gianfar: Add paged allocation and Rx S/G")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied.