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Date:   Fri, 5 Jun 2020 11:02:45 -0700 (PDT)
From:   Christian Kujau <lists@nerdbynature.de>
To:     =?UTF-8?Q?J=C3=BCrgen_Gro=C3=9F?= <jgross@suse.com>
cc:     linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org
Subject: Re: 5.7.0 / BUG: kernel NULL pointer dereference /
 setup_cpu_watcher
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On Fri, 5 Jun 2020, Jürgen Groß wrote:
> Do you happen to start the guest with vcpus < maxvcpus?

Indeed, I was booting with vcpus=2, maxvcpus=4. Setting both to the same 
value made the domU boot.

> If yes there is already a patch pending for 5.8:
> https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git/commit/?h=for-linus-5.8&id=c54b071c192dfe8061336f650ceaf358e6386e0b

Applied that manually and now the system boots even with vcpus < maxvcpus. 
So, if this still matters:
 
   Tested-by: Christian Kujau <lists@nerdbynature.de>

Thank you for your response, and the fix!

Christian.
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