Dear Devs, i was able to trace two of the segfaults with the trace-cmd as describes on the KVM bug reporting website. As I can not attach those big files here are the links to the files: https://share.ziegi.de/compile_switch_wlan_on_segfault-1.txt.gz https://share.ziegi.de/compile_switch_wlan_on_segfault-2.txt.gz It would be great if someone could give me a feedback on this, or direct me to where to post my question if this is not the right place for it. Thanks, Torsten Am 18.02.20 um 22:47 schrieb Torsten Ziegler: > Dear KVM Developers, > > i have a strange problem with segfaults in a guest system > while compiling a linux kernel. > > The basic setup (details below) is a ryzen cpu on a ab350 mainboard, > the host running ubuntu linux and guests running also debian based > linux. > Now i am compiling a vanilla linux kernel in the guest. > This will fail with random segfaults as soon as i enable a WLAN (USB > RTL8187L) connection in > the host system. > Apart from this everything is working fine. > As this WLAN is my default internet connection i did try different > virtualization setups > for almost a week until I could track down the problem. > > > The details: > CPU: Ryzen 7 2700X > same result using a Ryzen 5 1600 > > Mainboard: GA-AB350M-Gaming 3 > Bios: i tested with three versions: F31, F41d, F50a > > host system: > i tested with the following systems as host all x86_64 > ubuntu 19.10 kernel 5.3.0-26-generic > ubuntu 19.10 kernel 5.3.0-29-generic > ubuntu 20(development) kernel 5.4.0-14-generic > > kvm: > 4.0 (ubutu 19.10) and 4.2.0 (ubuntu 19.10 installed from sources) > 4.2.0 (ubuntu 20 dev) > > guest: > ubuntu 18.10 kernel 4.18.0-10-generic > debian 10 kernel 5.4.0-3-amd64 > > I use libvirt to launch the guests, so two example XML files are attached, > also the hypervisor info. > I tried a lot of different settings for cpu type and and cpu pinning > without much > difference. > > task: > Compile linux kernel on guest using debian linuc sources 5.4.8 or > vanilla 5.5.2 > > This works fine as long as I do not enable my WLAN internet connection > on the host (USB stick: NetGear, Inc. WG111v2 54 Mbps Wireless [RealTek > RTL8187L]) > > If I enable the WLAN (in the host) the guest starts producing random > compiler errors like these; > > ./include/linux/mm.h:2041:1: internal compiler error: Segmentation fault > static inline spinlock_t *pud_lockptr(struct mm_struct *mm, pud_t *pud) > ^~~~~~ > > ./include/linux/quota.h:338:1: internal compiler error: in tree_to_uhwi, at tree.h:4278 > }; > ^ > ./arch/x86/include/asm/pgtable.h:163:1: internal compiler error: Segmentation fault > { > ^ > elf.c:685:1: internal compiler error: Segmentation fault > } > ^ > > As soon as I disable the USB WLAN connection on the host (the USB stick > still > inserted) I can compile the kernels without any problem. > > No valuable messages in the log files of the host and the guest system. > > So I tested removing all Network Interfaces from the guest systems, > but this had no effect. Even without any networking a guest fails > compiling as soon as I > start the WLAN on the host system. > > I checked for electrical interference by > - using a long USB cable to get the WLAN stick away from the PC -> > compilation fails > - using a laptop operating the USB WLAN stick right beside the PC -> > compilation works fine > > I intensely tested the hosts RAM with memtest86+ > stressed the host system with compile jobs, > even did memtests on the guests. > But everythings seems rock solid. > > Does anyone have a clue, whats going on here, > or how i can debug this situation ? > > Thanks, > Torsten >
