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Subject: Re: [PATCH][RESEND] Revert "PM: ACPI: reboot: Use S5 for reboot"
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        "kernel-team@fb.com" <kernel-team@fb.com>
References: <b8db79e6857c41dab4ef08bdf826ea7c47e3bafc.1615947283.git.josef@toxicpanda.com>
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 <CAAd53p7eJk9EtMTLjB5i7RdoKA3WS1W4TRjQs08adi7iAux_jQ@mail.gmail.com>
From:   Josef Bacik <josef@toxicpanda.com>
Message-ID: <78dfcd55-442d-dcc0-c37f-5576f65f91b5@toxicpanda.com>
Date:   Wed, 17 Mar 2021 13:25:51 -0400
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On 3/17/21 12:14 PM, Kai-Heng Feng wrote:
> On Wed, Mar 17, 2021 at 11:19 PM Josef Bacik <josef@toxicpanda.com> wrote:
>>
>> On 3/16/21 10:50 PM, Kai-Heng Feng wrote:
>>> Hi,
>>>
>>> On Wed, Mar 17, 2021 at 10:17 AM Josef Bacik <josef@toxicpanda.com> wrote:
>>>>
>>>> This reverts commit d60cd06331a3566d3305b3c7b566e79edf4e2095.
>>>>
>>>> This patch causes a panic when rebooting my Dell Poweredge r440.  I do
>>>> not have the full panic log as it's lost at that stage of the reboot and
>>>> I do not have a serial console.  Reverting this patch makes my system
>>>> able to reboot again.
>>>
>>> But this patch also helps many HP laptops, so maybe we should figure
>>> out what's going on on Poweredge r440.
>>> Does it also panic on shutdown?
>>>
>>
>> Sure I'll test whatever to get it fixed, but I just wasted 3 days bisecting and
>> lost a weekend of performance testing on btrfs because of this regression, so
>> until you figure out how it broke it needs to be reverted so people don't have
>> to figure out why reboot suddenly isn't working.
> 
> That's unfortunate to hear. However, I've been spending tons of time
> on bisecting kernels. To me it's just a normal part of kernel
> development so I won't call it "wasted".
> 
> Feel free to revert the patch though.
> 
>>
>> Running "halt" has the same effect with and without your patch, it gets to
>> "system halted" and just sits there without powering off.  Not entirely sure why
>> that is, but there's no panic.
> 
> What about shutdown? pm_power_off_prepare() is used by shutdown but
> it's not used by halt.

"shutdown now" works fine with and without your patch.  Thanks,

Josef