Re: [PATCH 5.15 00/10] 5.15.62-rc2 review

[Guenter Roeck]

On Sun, Aug 21, 2022 at 03:32:55PM +0000, Stafford Horne wrote:
> On Sun, Aug 21, 2022 at 05:09:03AM -0700, Guenter Roeck wrote:
> > On Sat, Aug 20, 2022 at 08:23:24PM +0200, Greg Kroah-Hartman wrote:
> > > This is the start of the stable review cycle for the 5.15.62 release.
> > > There are 10 patches in this series, all will be posted as a response
> > > to this one.  If anyone has any issues with these being applied, please
> > > let me know.
> > > 
> > > Responses should be made by Mon, 22 Aug 2022 18:23:01 +0000.
> > > Anything received after that time might be too late.
> > > 
> > 
> > Build results:
> > 	total: 159 pass: 159 fail: 0
> > Qemu test results:
> > 	total: 485 pass: 484 fail: 1
> > Failed tests:
> > 	openrisc:or1ksim_defconfig
> > 
> > The openrisc failure is a soft lockup during restart. I only recently
> > enabled the soft lockup detector, so this is probably either a false
> > positive or not a new problem. I'll try to track it down, but it is
> > not a concern for now.
> > 
> > Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> 
> Hi Guenter,
> 
> If you need help let me know, just let me know how to reproduce it.  I am
> currently working on some qemu patches to convert qemu to multithread-tcg.  I
> have fixed some lockup issues, but there are still some cases we get soft
> lockups.
> 
> If you have any details I can see if it's a similar issue.
> 

All I can say is that it happens with qemu 7.0, it happens more or less
randomly with all kernel versions as far as I can see, and it isn't a real
lockup but something wrong with time management. The lockup is reported
almost immediately on shutdown. It reports something like

reboot: Restarting system
watchdog: BUG: soft lockup - CPU#0 stuck for 371s! [init:225]
Modules linked in:
CPU: 0 PID: 225 Comm: init Not tainted 6.0.0-rc1-00303-g963a70bee588 #1

but it doesn't really wait for that much time; the message is seen almost
immediately. I don't do anything special, just boot the openrisc emulation
and restart. I have the following options enabled.

CONFIG_LOCKUP_DETECTOR CONFIG_SOFTLOCKUP_DETECTOR CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC
CONFIG_DETECT_HUNG_TASK CONFIG_BOOTPARAM_HUNG_TASK_PANIC

The problem is not seen without those options.

Guenter