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[PATCH for v4.9 LTS 30/86] gianfar: Do not reuse pages from emergency reserve

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 69fed99baac186013840ced3524562841296034f ]

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@xxxxxxxxxx>
Cc: Claudiu Manoil <claudiu.manoil@xxxxxxxxxxxxx>
Acked-by: Claudiu Manoil <claudiu.manoil@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
 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 d391beebe591..3f4e71148808 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2951,7 +2951,7 @@ 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 */