On 25/11/16 18:11, Guenter Roeck wrote:
> Hi,
>
> I am using virtio on sparc64 for my Linux kernel runtime tests.
>
> Starting with qemu v2.7, I noticed that the kernel either gets stuck or
> crashes.
> After adding some debug information to the kernel, I found that the
> problem happens
> in vp_reset().
>
> Interestingly, when running v4.9-rc6 without modification, the kernel
> crashes on me.
> If I add pr_info just before and after the vp_iowrite8() in
> virtio_pci_modern.c:vp_reset(),
> the kernel gets stuck in the vp_iowrite8().
>
> Here is the relevant part of the crash:
>
> [ 3.151167] Unable to handle kernel NULL pointer dereference
> [ 3.151809] tsk->{mm,active_mm}->context = 0000000000000000
> [ 3.152430] tsk->{mm,active_mm}->pgd = fffff80000402000
> [ 3.153032] \|/ ____ \|/
> [ 3.153032] "@'/ .. \`@"
> [ 3.153032] /_| \__/ |_\
> [ 3.153032] \__U_/
> [ 3.154042] swapper(1): Oops [#1]
> [ 3.154773] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0-rc5+ #4
> [ 3.155375] task: fffff8001f0af620 task.stack: fffff8001f0b0000
> [ 3.155958] TSTATE: 0000009980001606 TPC: 00000000006edf44 TNPC:
> 00000000006edf48 Y: 00000000 Not tainted
> [ 3.156901] TPC: <vp_reset+0x4/0x40>
>
> None of the pointers used in vp_reset() is NULL. As mentioned above,
> adding a pr_info
> just before vp_iowrite8() makes the crash disappear and the kernel is
> stuck instead.
> Here is how it looks like:
>
> [ 3.104243] Hi there
> [ 26.912509] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 23s!
> [swapper:1]
> [ 26.913102] Modules linked in:
> [ 26.914061] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0-rc5+ #5
> [ 26.914633] task: fffff8001f0af620 task.stack: fffff8001f0b0000
> [ 26.915156] TSTATE: 0000004480001605 TPC: 00000000006edf50 TNPC:
> 00000000006edf54 Y: 00000412 Not tainted
> [ 26.915954] TPC: <vp_reset+0x10/0x60>
>
> Another pr_info() after vp_iowrite8() is never printed, suggesting that
> the code never
> gets to that point.
>
> The kernel configuration is sparc64_defconfig with the following
> configuration
> options enabled.
>
> CONFIG_DEVTMPFS=y
> CONFIG_VIRTIO=y
> CONFIG_VIRTIO_PCI=y
> CONFIG_VIRTIO_BLK=y
> CONFIG_VIRTIO_NET=y
> CONFIG_VIRTIO_BALLOON=y
> CONFIG_VIRTIO_CONSOLE=y
> CONFIG_SCSI_VIRTIO=y
>
> Command line is
>
> qemu-system-sparc64 -M sun4u -cpu "TI UltraSparc IIi" -m 512 \
> -drive file=simple-root-filesystem-sparc.ext3,if=virtio,format=raw \
> -kernel arch/sparc/boot/image -no-reboot \
> -append "root=/dev/vda init=/sbin/init.sh console=ttyS0" \
> -nographic -monitor none
>
> Does anyone have an idea what might be wrong ?
>
> Thanks,
> Guenter
Hi Guenter,
Have you been able to investigate this issue any further? Does the 2.8
release solve the issue for you?
ATB,
Mark.
