From: Nicholas Piggin <npiggin@gmail•com>
To: bugzilla-daemon@bugzilla•kernel.org, linuxppc-dev@lists•ozlabs.org
Subject: Re: [Bug 206669] Little-endian kernel crashing on POWER8 on heavy big-endian PowerKVM load
Date: Wed, 26 Feb 2020 21:03:51 +1000 [thread overview]
Message-ID: <1582714660.bopln5sr51.astroid@bobo.none> (raw)
In-Reply-To: <bug-206669-206035-ZVCbFl0u4b@https.bugzilla.kernel.org/>
bugzilla-daemon@bugzilla•kernel.org's on February 26, 2020 8:28 pm:
> https://bugzilla.kernel.org/show_bug.cgi?id=206669
>
> --- Comment #4 from John Paul Adrian Glaubitz (glaubitz@physik•fu-berlin.de) ---
> (In reply to npiggin from comment #3)
>> Do you have tracing / ftrace enabled in the host kernel for any
>> reason? Turning that off might let the oops message get printed.
>
> Seems that this is the case in the Debian kernel, yes:
>
> root@watson:~# grep -i ftrace /boot/config-5.4.0-0.bpo.3-powerpc64le
> CONFIG_KPROBES_ON_FTRACE=y
> CONFIG_HAVE_KPROBES_ON_FTRACE=y
> CONFIG_HAVE_DYNAMIC_FTRACE=y
> CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS=y
> CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
> CONFIG_FTRACE=y
> CONFIG_FTRACE_SYSCALLS=y
> CONFIG_DYNAMIC_FTRACE=y
> CONFIG_DYNAMIC_FTRACE_WITH_REGS=y
> CONFIG_FTRACE_MCOUNT_RECORD=y
> # CONFIG_FTRACE_STARTUP_TEST is not set
> root@watson:~#
>
> Do you have the kernel command option at hand which disables ftrace on the
> command line? Is it just ftrace=off?
Hmm, not sure, Documentation/admin-guide/kernel-parameters.txt seems
to say that wouldn't work.
I thought it might only be going down that path if you have already done
some tracing. Perhaps ensure /sys/kernel/debug/tracing/tracing_on is set
to 0, and then `echo 1 > /sys/kernel/debug/tracing/free_buffer` before
you start the test.
>> > FWIW, the kernel image comes from this Debian package:
>> >
>> >>
>> >>
>> >>
>> http://snapshot.debian.org/archive/debian/20200211T210433Z/pool/main/l/linux/linux-image-5.4.0-0.bpo.3-powerpc64le_5.4.13-1%7Ebpo10%2B1_ppc64el.deb
>>
>> Okay. Any chance you could test an upstream kernel?
>
> Sure, absolutely. Any preference on the version number?
Current head if you're feeling lucky, but v5.5 if not. But you can
give the ftrace test a try with the debian kernel first if you've got
it ready to go.
>> Don't bother testing that after the above -- panic_on_oops happens
>> after oops_begin(), so it won't help unfortunately.
>
> Okay.
>
>> Attmepting to get into xmon might though, if you boot with xmon=on.
>> Try that if tracing wasn't enabled, or disabling it doesn't help.
>
> Okay. I will try to disable ftrace first, then retrigger the crash.
Cool
Thanks,
Nick
next prev parent reply other threads:[~2020-02-26 11:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-25 15:26 [Bug 206669] New: Little-endian kernel crashing on POWER8 on heavy big-endian PowerKVM load bugzilla-daemon
2020-02-26 4:02 ` Nicholas Piggin
2020-02-26 4:06 ` [Bug 206669] " bugzilla-daemon
2020-02-26 7:26 ` bugzilla-daemon
2020-02-26 9:25 ` Nicholas Piggin
2020-02-26 9:29 ` bugzilla-daemon
2020-02-26 10:28 ` bugzilla-daemon
2020-02-26 11:03 ` Nicholas Piggin [this message]
2020-02-26 11:08 ` bugzilla-daemon
2020-02-26 12:02 ` bugzilla-daemon
2020-02-27 16:07 ` bugzilla-daemon
2020-03-07 21:56 ` bugzilla-daemon
2020-03-10 12:25 ` bugzilla-daemon
2020-03-10 12:28 ` bugzilla-daemon
2020-03-14 10:08 ` bugzilla-daemon
2020-03-16 18:13 ` bugzilla-daemon
2020-03-19 20:22 ` bugzilla-daemon
2021-09-10 9:40 ` bugzilla-daemon
2021-09-13 8:52 ` bugzilla-daemon
2021-09-13 9:24 ` bugzilla-daemon
2021-09-30 15:44 ` bugzilla-daemon
2021-10-25 8:45 ` bugzilla-daemon
2022-01-31 9:53 ` bugzilla-daemon
2022-07-29 7:02 ` bugzilla-daemon
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