From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932176Ab3KNVHQ (ORCPT ); Thu, 14 Nov 2013 16:07:16 -0500 Received: from shards.monkeyblade.net ([149.20.54.216]:52829 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758020Ab3KNVGr (ORCPT ); Thu, 14 Nov 2013 16:06:47 -0500 Date: Thu, 14 Nov 2013 16:06:44 -0500 (EST) Message-Id: <20131114.160644.936677620948788988.davem@davemloft.net> To: jasowang@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, stefanha@redhat.com, gregory.v.rose@intel.com Subject: Re: [PATCH net V2 2/2] macvtap: limit head length of skb allocated From: David Miller In-Reply-To: <1384322440-29038-2-git-send-email-jasowang@redhat.com> References: <1384322440-29038-1-git-send-email-jasowang@redhat.com> <1384322440-29038-2-git-send-email-jasowang@redhat.com> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.1 (shards.monkeyblade.net [0.0.0.0]); Thu, 14 Nov 2013 13:06:46 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jason Wang Date: Wed, 13 Nov 2013 14:00:40 +0800 > 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 > Cc: Michael S. Tsirkin > Signed-off-by: Jason Wang Applied and queued up for -stable.