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Date:   Thu, 13 Oct 2022 15:03:14 +1000
Message-Id: <CNKJ6FE6U35I.3ERMDQR9MHRLX@bobo>
From:   "Nicholas Piggin" <npiggin@gmail.com>
To:     "Guenter Roeck" <linux@roeck-us.net>,
        "Michael Ellerman" <mpe@ellerman.id.au>
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
        "Linus Torvalds" <torvalds@linux-foundation.org>,
        <ajd@linux.ibm.com>, <aneesh.kumar@linux.ibm.com>,
        <atrajeev@linux.vnet.ibm.com>, <christophe.leroy@csgroup.eu>,
        <cuigaosheng1@huawei.com>, <david@redhat.com>,
        <farosas@linux.ibm.com>, <geoff@infradead.org>,
        <gustavoars@kernel.org>, <haren@linux.ibm.com>,
        <hbathini@linux.ibm.com>, <joel@jms.id.au>, <lihuafei1@huawei.com>,
        <linux-kernel@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>,
        <lukas.bulwahn@gmail.com>, <mikey@neuling.org>,
        <nathan@kernel.org>, <nathanl@linux.ibm.com>,
        <nicholas@linux.ibm.com>, <pali@kernel.org>, <paul@paul-moore.com>,
        <rmclure@linux.ibm.com>, <ruscur@russell.cc>, <windhl@126.com>,
        <wsa+renesas@sang-engineering.com>, <ye.xingchen@zte.com.cn>,
        <yuanjilin@cdjrlc.com>, <zhengyongjun3@huawei.com>
Subject: Re: [GIT PULL] Please pull powerpc/linux.git powerpc-6.1-1 tag
References: <87edvhntv0.fsf@mpe.ellerman.id.au>
 <20221012141827.GA2405914@roeck-us.net> <Y0biBtCUtc2mowbQ@zx2c4.com>
 <20221012164452.GA2990467@roeck-us.net> <Y0b3ZsTRHWG6jGK8@zx2c4.com>
 <20221012221615.GA364143@roeck-us.net> <87bkqgmvxl.fsf@mpe.ellerman.id.au>
 <20221013002148.GA535574@roeck-us.net>
In-Reply-To: <20221013002148.GA535574@roeck-us.net>
Precedence: bulk

On Thu Oct 13, 2022 at 10:21 AM AEST, Guenter Roeck wrote:
> On Thu, Oct 13, 2022 at 11:03:34AM +1100, Michael Ellerman wrote:
> > Guenter Roeck <linux@roeck-us.net> writes:
> > > On Wed, Oct 12, 2022 at 11:20:38AM -0600, Jason A. Donenfeld wrote:
> > >>=20
> > >> I've also managed to not hit this bug a few times. When it triggers,
> > >> after "kprobes: kprobe jump-optimization is enabled. All kprobes are
> > >> optimized if possible.", there's a long hang - tens seconds before i=
t
> > >> continues. When it doesn't trigger, there's no hang at that point in=
 the
> > >> boot process.
> > >>=20
> > >
> > > I managed to bisect the problem. See below for results. Reverting the
> > > offending patch fixes the problem for me.
> >=20
> > Thanks.
> >=20
> > This is probably down to me/us not testing with PREEMPT enabled enough.
> >=20
> Not sure. My configuration has
>
> CONFIG_PREEMPT_NONE=3Dy
> # CONFIG_PREEMPT_VOLUNTARY is not set
> # CONFIG_PREEMPT is not set

Thanks very much for helping with this. The config snippet you posted here
https://lists.ozlabs.org/pipermail/linuxppc-dev/2022-October/249758.html
has CONFIG_PREEMPT=3Dy. How do you turn that into a .config, olddefconfig?

I can't reproduce this so far using your config and qemu command line,
but the patch you've bisected it to definitely could cause this. I'll
keep trying...

Thanks,
Nick

[...]
> > > # first bad commit: [e485f6c751e0a969327336c635ca602feea117f0] powerp=
c/64/interrupt: Fix return to masked context after hard-mask irq becomes pe=
nding