Date:   Fri, 10 Feb 2023 01:39:01 +0100
From:   Frederic Weisbecker <frederic@kernel.org>
To:     Zqiang <qiang1.zhang@intel.com>,
        Nicholas Piggin <npiggin@gmail.com>
Cc:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        paulmck@kernel.org, joel@joelfernandes.org, rcu@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] sched/isolation: Fix illegal CPU value by
 housekeeping_any_cpu() return
Message-ID: <Y+WSJRjlB4qDI1ul@lothringen>
References: <20230210000021.1007853-1-qiang1.zhang@intel.com>
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Thanks for checking this!

On Fri, Feb 10, 2023 at 08:00:21AM +0800, Zqiang wrote:
> For kernels built with CONFIG_NO_HZ_FULL=y, running the following tests:
> 
> runqemu kvm slirp nographic qemuparams="-m 1024 -smp 4" bootparams=
> "console=ttyS0 nohz_full=0,1 rcu_nocbs=0,1 sched_verbose" -d

Has this ever worked? Again I'm tempted to just:

    git revert 08ae95f4fd3b38b257f5dc7e6507e071c27ba0d5

> 
> root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu2/online
> root@qemux86-64:~# echo 0 > /sys/devices/system/cpu/cpu3/online
> 
> [   22.838290] BUG: unable to handle page fault for address: ffffffff84cd48c0