https://bugzilla.kernel.org/show_bug.cgi?id=75331 Bug ID: 75331 Summary: "soft lockup CPU#0 stuck for 23s" regression on 32bit 3.13.0+ kernels. Product: Virtualization Version: unspecified Kernel Version: 3.13.0+ Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: iive@xxxxxxxxx Regression: No Created attachment 134761 --> https://bugzilla.kernel.org/attachment.cgi?id=134761&action=edit dmesg log and kernel .config I'm getting "soft lockup CPU#0 stuck for 23s" when running qemu 1.7.0 with kvm on vanilla kernels 3.13.0 and above. All builds are 32 bit. The lockup happens shortly after starting the guest OS, sometimes even before the guest boot is complete. The cpu graph shows one core running in kernel mode, the guest freezes, qemu is still responsive. Sometimes the lockup goes away after a while, then comes back. The first time I didn't kill qemu and it managed to lock my system. I'm not using virtio/xen or other frameworks. Just bare qemu. I've tried to remove network and sound devices but it had no measurable impact. Having -usb and -smp 4 seems to make triggering the lockup much easier/faster but removing them doesn't eliminate lockups. (Or lockups may be random and not related to these options.) With some help, I started a `git bisect` on the Linus' repository. I did manage to locate a commit that when reversed eliminates the problem completely (tested on 3.14.1 kernel that previously had this problem). The commit is : --------- commit e0f6dec35f9286e78879fe1ac92803fd69fc4fdc Author: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Date: Wed Dec 4 14:31:28 2013 -0800 x86, bitops: Correct the assembly constraints to testing bitops --------- I'm with gcc-4.8.2 on latest Slackware. To this bugreport I'm attaching tgz archive with the 3.14.0 kernel `.config` file and `dmesg` extracted from the vmcore. On request I could provide vmcore and vmlinux of 3.14.0 compiled with debug info. (75MB each, when gzipped/stripped by `makedumpfile`) Qemu is compiled with: ./configure --disable-strip --audio-drv-list=oss,alsa,sdl --disable-bsd-user --enable-vnc --target-list=i386-softmmu,i386-linux-user Qemu is started with : qemu -smp 4 -usb -enable-kvm -vga cirrus -net none -ctrl-grab -display sdl -hda guest.qcow2 -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
