Re: [PATCH V4 2/2] perf/x86/intel/ds: Delay the threshold update

[Peter Zijlstra]

On Thu, May 04, 2023 at 11:11:23AM +0200, Peter Zijlstra wrote:
> On Tue, Apr 25, 2023 at 03:16:29PM +0800, kernel test robot wrote:
> > Hello,
> > 
> > kernel test robot noticed "Kernel_panic-not_syncing:Timeout:Not_all_CPUs_entered_broadcast_exception_handler" on:
> > 
> > commit: a17c97370d1fb9b2eac75c85136a1f70ec44eded ("[PATCH V4 2/2] perf/x86/intel/ds: Delay the threshold update")
> > url: https://github.com/intel-lab-lkp/linux/commits/kan-liang-linux-intel-com/perf-x86-intel-ds-Delay-the-threshold-update/20230422-024743
> > base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 15def34e2635ab7e0e96f1bc32e1b69609f14942
> > patch link: https://lore.kernel.org/all/20230421184529.3320912-2-kan.liang@xxxxxxxxxxxxxxx/
> > patch subject: [PATCH V4 2/2] perf/x86/intel/ds: Delay the threshold update
> > 
> > in testcase: kvm-unit-tests-qemu
> > 
> > compiler: gcc-11
> > test machine: 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480+ (Sapphire Rapids) with 256G memory
> > 
> > (please refer to attached dmesg/kmsg for entire log/backtrace)
> > 
> > 
> > If you fix the issue, kindly add following tag
> > | Reported-by: kernel test robot <yujie.liu@xxxxxxxxx>
> > | Link: https://lore.kernel.org/oe-lkp/202304251457.d108dbb3-yujie.liu@xxxxxxxxx
> > 
> > 
> > [  179.997768][ T2324] 2023-04-23 15:30:10 ./run_tests.sh
> > ...
> > [  180.442663][T20263] x86/split lock detection: #AC: qemu-system-x86/20263 took a split_lock trap at address: 0x1e3
> > [  182.372875][ T2324] 
> 
> I'm going to try and replicate this on my ADL which should have
> split_lock crud on. How does one run this kvm-unit-test stuff, inside
> kvm or on bare metal?

Bare metal it is..

Anyway, on the ADL I can see the split lock thing with or without the
patches in question so thta can't be it.