From: Jason Wang <jasowang@redhat.com>
To: davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, mst@redhat.com,
stefanha@redhat.com
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH net 1/2] tuntap: limit head length of skb allocated
Date: Tue, 12 Nov 2013 18:02:56 +0800 [thread overview]
Message-ID: <1384250577-20330-1-git-send-email-jasowang@redhat.com> (raw)
We currently use hdr_len as a hint of head length which is advertised by
guest. But when guest advertise a very big value, it can lead to an 64K+
allocating of kmalloc() which has a very high possibility of failure when host
memory is fragmented or under heavy stress. The huge hdr_len also reduce the
effect of zerocopy or even disable if a gso skb is linearized in guest.
To solves those issues, this patch introduces an upper limit (PAGE_SIZE) of the
head, which guarantees an order 0 allocation each time.
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
The patch was needed for stable.
---
drivers/net/tun.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7cb105c..5537b65 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -954,6 +954,11 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
struct sock *sk = tfile->socket.sk;
struct sk_buff *skb;
int err;
+ int good_linear = SKB_MAX_HEAD(prepad);
+
+ /* Don't use huge linear part */
+ if (linear > good_linear)
+ linear = good_linear;
/* Under a page? Don't bother with paged skb. */
if (prepad + len < PAGE_SIZE || !linear)
--
1.8.3.2
next reply other threads:[~2013-11-12 10:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-12 10:02 Jason Wang [this message]
2013-11-12 10:02 ` [PATCH net 2/2] macvtap: limit head length of skb allocated Jason Wang
2013-11-12 11:20 ` Michael S. Tsirkin
2013-11-12 17:45 ` Greg Rose
2013-11-13 5:58 ` Jason Wang
2013-11-12 11:20 ` [PATCH net 1/2] tuntap: " Michael S. Tsirkin
2013-11-12 14:21 ` Jason Wang
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