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From:   Miaohe Lin <linmiaohe@huawei.com>
To:     <davem@davemloft.net>, <kuba@kernel.org>,
        <martin.varghese@nokia.com>, <fw@strlen.de>, <pshelar@ovn.org>,
        <dcaratti@redhat.com>, <edumazet@google.com>,
        <steffen.klassert@secunet.com>, <pabeni@redhat.com>,
        <shmulik@metanetworks.com>, <kyk.segfault@gmail.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linmiaohe@huawei.com>
Subject: [PATCH] net: Relax the npages test against MAX_SKB_FRAGS
Date:   Tue, 18 Aug 2020 07:57:12 -0400
Message-ID: <20200818115712.36497-1-linmiaohe@huawei.com>
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The npages test against MAX_SKB_FRAGS can be relaxed if we succeed to
allocate high order pages as the note in comment said.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 net/core/skbuff.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 2f7dd689bccc..ca432bbfd90b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5758,13 +5758,6 @@ struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
 	struct page *page;
 	int i;
 
-	*errcode = -EMSGSIZE;
-	/* Note this test could be relaxed, if we succeed to allocate
-	 * high order pages...
-	 */
-	if (npages > MAX_SKB_FRAGS)
-		return NULL;
-
 	*errcode = -ENOBUFS;
 	skb = alloc_skb(header_len, gfp_mask);
 	if (!skb)
@@ -5775,6 +5768,10 @@ struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
 	for (i = 0; npages > 0; i++) {
 		int order = max_page_order;
 
+		if (unlikely(i >= MAX_SKB_FRAGS)) {
+			*errcode = -EMSGSIZE;
+			goto failure;
+		}
 		while (order) {
 			if (npages >= 1 << order) {
 				page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
-- 
2.19.1