[Devel] [PATCH]net: Restore default sock_alloc_send_pskb() changed by initial cumulative patch

[Kirill Tkhai]

Some of pre-2.6.32 kernel need linear skb allocation for these places. The most
probably, it's connected with problems of memory accounting then.

But now, these hunks creates problem for VMs, because allocation of continuous
big skbs fails there.

Restore the default behaviour to fix the problem.

https://jira.sw.ru/browse/PSBM-52390

Reported-by: Roman Kagan <rkagan at virtuozzo.com>
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a128823..d589b6d 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -605,7 +605,12 @@ static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad,
 {
 	struct sk_buff *skb;
 
-	skb = sock_alloc_send_skb(sk, prepad + linear, noblock, err);
+	/* Under a page?  Don't bother with paged skb. */
+	if (prepad + len < PAGE_SIZE || !linear)
+		linear = len;
+
+	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
+				   err, 0);
 	if (!skb)
 		return NULL;
 
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index dabe51c..75c627b 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1028,8 +1028,12 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
 	struct sk_buff *skb;
 	int err;
 
-	linear = len;
-	skb = sock_alloc_send_skb(sk, prepad + linear, noblock, &err);
+	/* Under a page?  Don't bother with paged skb. */
+	if (prepad + len < PAGE_SIZE || !linear)
+		linear = len;
+
+	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
+				   &err, 0);
 	if (!skb)
 		return ERR_PTR(err);