Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754089Ab2EPPEY (ORCPT ); Wed, 16 May 2012 11:04:24 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:50688 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753220Ab2EPPEW (ORCPT ); Wed, 16 May 2012 11:04:22 -0400 Subject: Re: [V2 PATCH 2/9] macvtap: zerocopy: fix truesize underestimation From: Shirley Ma To: Jason Wang Cc: eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, davem@davemloft.net In-Reply-To: <4FB3192E.4030803@redhat.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> <1337102809.8220.10.camel@oc3660625478.ibm.com> <4FB3192E.4030803@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 16 May 2012 08:03:05 -0700 Message-ID: <1337180585.10741.6.camel@oc3660625478.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-24.el6) Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12051615-6148-0000-0000-000005E56964 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1511 Lines: 40 On Wed, 2012-05-16 at 11:04 +0800, Jason Wang wrote: > >> 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? > > > > We get the whole user page, so need to account them all. Also this is > aligned with skb_copy_ubufs(). Then this would double count the size of "first" offset left from previous copy, both skb->len and truesize. Thanks Shirley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/