BUG: 'list_empty(&vgdev->free_vbufs)' is true!
jslaby at suse.cz
Thu Dec 15 13:01:12 UTC 2016
On 11/16/2016, 02:12 PM, Gerd Hoffmann wrote:
> On Fr, 2016-11-11 at 17:28 +0100, Jiri Slaby wrote:
>> On 11/09/2016, 09:01 AM, Gerd Hoffmann wrote:
>>> On Di, 2016-11-08 at 22:37 +0200, Michael S. Tsirkin wrote:
>>>> On Mon, Nov 07, 2016 at 09:43:24AM +0100, Jiri Slaby wrote:
>>>>> I can relatively easily reproduce this bug:
>> Run dmesg -w in the qemu window (virtio_gpu) to see a lot of output.
>> Run pps  without exit(0); on e.g. serial console.
>> Wait a bit. The lot of output causes the BUG.
>>  https://github.com/jirislaby/collected_sources/blob/master/pps.c
> Doesn't reproduce here.
> Running "while true; do dmesg; done" on the virtio-gpu fbcon.
> Running the pps fork bomb on the serial console.
> Can watch dmesg printing the kernel messages over and over, until the
> shell can't spawn dmesg any more due to the fork bomb hitting the
> process limit. No BUG() triggered.
> Tried spice, gtk and sdl.
> Any ideas what else might be needed to reproduce it?
I can reproduce even with count = 32 :(. And without the fork bomb (i.e.
with the code from the repository).
This is how I start qemu:
/usr/bin/qemu-system-x86_64 -machine accel=kvm -k en-us -smp 4 -m 2371
-usb -device virtio-rng-pci -drive
-device virtio-scsi-pci,id=scsi -device scsi-hd,drive=hd -soundhw hda
-net nic,model=virtio -serial pty -balloon virtio -device
virtio-tablet-pci -vga virtio -kernel
/home/latest/my/arch/x86/boot/bzImage -append root=/dev/sda1
console=ttyS0,115200 loglevel=debug -snapshot
dmesg -w # on the console
and on serial console:
while :; do for aa in `seq 1 10`; do ./pps & done; wait; done
Note the latter can cause interrupt "storm" (~ 700 irqs per second) as
much output is generated. This can lead to some race condition. serial
is on IRQ4 and virtio gpu on IRQ10 which has lower priority AFAIK.
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