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Message-ID: <bfa768e7-fc4f-4511-ad3a-67772f41d50c@paulmck-laptop>
Date: Sun, 30 Jul 2023 20:54:46 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Joel Fernandes <joel@...lfernandes.org>,
Pavel Machek <pavel@...x.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, patches@...ts.linux.dev,
linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, shuah@...nel.org, patches@...nelci.org,
lkft-triage@...ts.linaro.org, jonathanh@...dia.com,
f.fainelli@...il.com, sudipm.mukherjee@...il.com,
srw@...dewatkins.net, rwarsow@....de, conor@...nel.org,
rcu@...r.kernel.org
Subject: Re: [PATCH 6.4 000/227] 6.4.7-rc1 review
On Thu, Jul 27, 2023 at 09:22:52PM -0700, Guenter Roeck wrote:
> On 7/27/23 13:33, Paul E. McKenney wrote:
> [ ... ]
>
> > So which of the following Kconfig options is defined in your .config?
> > CONFIG_TASKS_RCU, CONFIG_TASKS_RUDE_RCU, and CONFIG_TASKS_TRACE_RCU.
> >
>
> Only CONFIG_TASKS_RCU. I added another log message after call_rcu_tasks().
> It never returns from that function.
>
> [ 1.168993] Running RCU synchronous self tests
> [ 1.169219] Running RCU synchronous self tests
> [ 1.285795] smpboot: CPU0: Intel Xeon Processor (Cascadelake) (family: 0x6, model: 0x55, stepping: 0x6)
> [ 1.302827] RCU Tasks: Setting shift to 0 and lim to 1 rcu_task_cb_adjust=1.
> [ 1.304526] Running RCU Tasks wait API self tests
>
> ... and then nothing for at least 10 minutes (then I gave up and stopped the test).
>
> Qemu command line:
>
> qemu-system-x86_64 -kernel \
> arch/x86/boot/bzImage -M q35 -cpu Cascadelake-Server -no-reboot \
> -snapshot -device e1000e,netdev=net0 -netdev user,id=net0 -m 256 \
> -drive file=rootfs.iso,format=raw,if=ide,media=cdrom \
> --append "earlycon=uart8250,io,0x3f8,9600n8 panic=-1 slub_debug=FZPUA root=/dev/sr0 rootwait console=ttyS0 noreboot" \
> -d unimp,guest_errors -nographic -monitor none
>
> Again, this doesn't happen all the time. With Cascadelake-Server
> I see it maybe once every 5 boot attempts. I tried with qemu v8.0
> and v8.1. Note that it does seem to happen with various CPU types,
> only for some it seems to me more likely to happen (so maybe the
> CPU type was a red herring). It does seem to depend on the system
> load, and happen more often if the system is under heavy load.
Hmmm... What kernel are you using as your qemu/KVM hypervisor?
And I echo Joel's requests for your .config file.
Thanx, Paul
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