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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Huazhong tan <tanhuazhong@huawei.com>,
        Salil Mehta <salil.mehta@huawei.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 193/228] net: hns: fix skb->truesize underestimation
Date:   Tue,  2 Oct 2018 06:24:50 -0700
Message-Id: <20181002132511.116117481@linuxfoundation.org>
In-Reply-To: <20181002132459.032960735@linuxfoundation.org>
References: <20181002132459.032960735@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Huazhong Tan <tanhuazhong@huawei.com>

[ Upstream commit b1ccd4c0ab6ef499f47dd84ed4920502a7147bba ]

skb->truesize is not meant to be tracking amount of used bytes in a skb,
but amount of reserved/consumed bytes in memory.

For instance, if we use a single byte in last page fragment, we have to
account the full size of the fragment.

So skb_add_rx_frag needs to calculate the length of the entire buffer into
turesize.

Fixes: 9cbe9fd5214e ("net: hns: optimize XGE capability by reducing cpu usage")
Signed-off-by: Huazhong tan <tanhuazhong@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/hisilicon/hns/hns_enet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
@@ -530,7 +530,7 @@ static void hns_nic_reuse_page(struct sk
 	}
 
 	skb_add_rx_frag(skb, i, desc_cb->priv, desc_cb->page_offset + pull_len,
-			size - pull_len, truesize - pull_len);
+			size - pull_len, truesize);
 
 	 /* avoid re-using remote pages,flag default unreuse */
 	if (unlikely(page_to_nid(desc_cb->priv) != numa_node_id()))