From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shirley Ma Subject: Re: [V2 PATCH 2/9] macvtap: zerocopy: fix truesize underestimation Date: Tue, 15 May 2012 10:26:49 -0700 Message-ID: <1337102809.8220.10.camel@oc3660625478.ibm.com> References: <20120502033901.11782.13157.stgit@amd-6168-8-1.englab.nay.redhat.com> <20120502034144.11782.88947.stgit@amd-6168-8-1.englab.nay.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, davem@davemloft.net To: Jason Wang Return-path: In-Reply-To: <20120502034144.11782.88947.stgit@amd-6168-8-1.englab.nay.redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 2012-05-02 at 11:41 +0800, Jason Wang wrote: > 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 > --- > drivers/net/macvtap.c | 6 ++++-- > 1 files 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; Here should be truesize = size * PAGE_SIZE - offset, right? > 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); > >