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Subject[ 017/108] macvtap: zerocopy: fix truesize underestimation
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Jason Wang <jasowang@redhat.com>

commit 4ef67ebedffa44ed9939b34708ac2fee06d2f65f upstream.

As the skb fragment were pinned/built from user pages, we should
account the page instead of length for truesize.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/net/macvtap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index bd4a70d..7cb2684 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -519,6 +519,7 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
struct page *page[MAX_SKB_FRAGS];
int num_pages;
unsigned long base;
+ unsigned long truesize;

len = from->iov_len - offset;
if (!len) {
@@ -533,10 +534,11 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
(num_pages > MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags))
/* put_page is in skb free */
return -EFAULT;
+ truesize = size * PAGE_SIZE;
skb->data_len += len;
skb->len += len;
- skb->truesize += len;
- atomic_add(len, &skb->sk->sk_wmem_alloc);
+ skb->truesize += truesize;
+ atomic_add(truesize, &skb->sk->sk_wmem_alloc);
while (len) {
int off = base & ~PAGE_MASK;
int size = min_t(int, len, PAGE_SIZE - off);




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