From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH] vhost-net: fall back to vmalloc if high-order allocation fails Date: Fri, 25 Jan 2013 13:15:51 +0800 Message-ID: <4164122.3gtdQVSA24@jason-thinkpad-t430s> References: <87k3r31vbc.fsf@silenus.orebokech.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Cong Wang Return-path: Received: from mx1.redhat.com ([209.132.183.28]:3764 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776Ab3AYFP4 (ORCPT ); Fri, 25 Jan 2013 00:15:56 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Friday, January 25, 2013 03:03:13 AM Cong Wang wrote: > ["Followup-To:" header set to gmane.linux.network.] > > On Wed, 23 Jan 2013 at 20:46 GMT, Romain Francoise wrote: > > Creating a vhost-net device allocates an object large enough (34320 bytes > > on x86-64) to trigger an order-4 allocation, which may fail if memory if > > > > fragmented: > > libvirtd: page allocation failure: order:4, mode:0x2000d0 > > ... > > SLAB: Unable to allocate memory on node 0 (gfp=0xd0) > > > > cache: size-65536, object size: 65536, order: 4 > > node 0: slabs: 8/8, objs: 8/8, free: 0 > > > > In that situation, rather than forcing the caller to use regular > > virtio-net, try to allocate the descriptor with vmalloc(). > > The real problem is vhost_net struct is really big, it > should be reduced rather than workarounded like this. > Looks like iov in vhost_virtqueue is a little big: struct iovec iov[UIO_MAXIOV]; Maybe we can use pointer and allocate it like indirect in vhost_dev_alloc_iovecs(). > > +static void vhost_net_kvfree(void *addr) > > +{ > > + if (is_vmalloc_addr(addr)) > > + vfree(addr); > > + else > > + kfree(addr); > > +} > > + > > This kind of stuff should really go to mm, not netdev. > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html