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Date: Fri, 15 Jul 2016 10:28:25 +1000
From: Anton Blanchard <anton@samba.org>
To: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Bharata B Rao <bharata@linux.vnet.ibm.com>,
        Christophe Jaillet <christophe.jaillet@wanadoo.fr>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>,
        Paul Mackerras <paulus@samba.org>,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [patch V2 30/67] powerpc/numa: Convert to hotplug state machine
Message-ID: <20160715102825.34d60395@kryten>
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Hi Anna-Maria,

> >> Install the callbacks via the state machine and let the core invoke
> >> the callbacks on the already online CPUs.  
> >
> > This is causing an oops on ppc64le QEMU, looks like a NULL
> > pointer:  
> 
> Did you tested it against tip WIP.hotplug?

I noticed tip started failing in my CI environment which tests on QEMU.
The failure bisected to commit 425209e0abaf2c6e3a90ce4fedb935c10652bf80

It reproduces running ppc64le QEMU on a x86-64 box. On Ubuntu:

sudo apt-get install qemu-system-ppc gcc-powerpc64le-linux-gnu

make ARCH=powerpc pseries_le_defconfig

make ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- vmlinux -j4

qemu-system-ppc64 -nographic -vga none -kernel vmlinux 

Anton