On Sat, 23 Dec 2017 08:27:25 +0000 "Zhoujian (jay)" <jianjay.z...@huawei.com> wrote:
> > > > -----Original Message----- > > From: Igor Mammedov [mailto:imamm...@redhat.com] > > Sent: Saturday, December 23, 2017 2:49 AM > > To: Zhoujian (jay) <jianjay.z...@huawei.com> > > Cc: qemu-devel@nongnu.org; m...@redhat.com; Huangweidong (C) > > <weidong.hu...@huawei.com>; Gonglei (Arei) <arei.gong...@huawei.com>; > > wangxin (U) <wangxinxin.w...@huawei.com>; Liuzhe (Cloud Open Labs, NFV) > > <gary.liu...@huawei.com>; dgilb...@redhat.com > > Subject: Re: [PATCH v2 2/2] vhost: double check used memslots number > > > > On Fri, 15 Dec 2017 16:45:55 +0800 > > Jay Zhou <jianjay.z...@huawei.com> wrote: > > > > > If the VM already has N(N>8) available memory slots for vhost user, > > > the VM will be crashed in vhost_user_set_mem_table if we try to > > > hotplug the first vhost user NIC. > > > This patch checks if memslots number exceeded or not after updating > > > vhost_user_used_memslots. > > Can't understand commit message, pls rephrase (what is being fixed, and > > how it's fixed) also include reproducing steps for crash and maybe > > describe call flow/backtrace that triggers crash. > > Sorry about my pool english > > > > > PS: > > I wasn't able to reproduce crash > > Steps to reproduce: > (1) start up a VM successfully without any vhost device > (2) hotplug 8 DIMM memory successfully > (3) hotplug a vhost-user NIC, the VM crashed, it asserted > at the line > assert(fd_num < VHOST_MEMORY_MAX_NREGIONS); quick fix for this crash could be: diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 093675ed98..07a37537dd 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -321,7 +321,9 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev, msg.payload.memory.regions[fd_num].memory_size = reg->memory_size; msg.payload.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr; msg.payload.memory.regions[fd_num].mmap_offset = offset; - assert(fd_num < VHOST_MEMORY_MAX_NREGIONS); + if (fd_num == VHOST_MEMORY_MAX_NREGIONS) { + return -1; + } fds[fd_num++] = fd; } } it should gracefully prevent device to start. > in vhost_user_set_mem_table() > > Regards, > Jay [...]
