linux-kernel - Re: Hibernate resume bug around 3,18-rc2

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Date:	Fri, 20 Nov 2015 09:47:08 +0100
From:	Juergen Gross <jgross@...e.com>
To:	vasvir@....demokritos.gr
Cc:	linux-kernel@...r.kernel.org, Toshi Kani <toshi.kani@...com>,
	"Luis R. Rodriguez" <mcgrof@...e.com>
Subject: Re: Hibernate resume bug around 3,18-rc2 - Full PAT support

On 20/11/15 06:25, Vassilis Virvilis wrote:
> On 11/19/2015 10:35 PM, Vassilis Virvilis wrote:
>>
>> I compiled and I am running 4.3 right now.
>>
> 
> It failed this morning. Last night I did 3 hibernate / resume cycles. In
> the last one I I also turned off the PSU (this seems to push it over the
> edge - but it may be random behavior) and it worked. This morning 7h
> later failed to resume - but it didn't hang on _lapic_resume. This time
> it rebooted - and I seem to recall this behavior for 4.2+ kernels. I
> forgot to mention it because my testing with 4.x kernels were one month
> before.
> 
> So 4.3 kernel - reboots on resume after a long hibernation time.
> 
> I am testing with 4.3 and nopat right now.

I've just found a potential issue: In case MTRR is disabled by the BIOS
the PAT register of the boot processor won't be restored after resume.

Can you check whether pr_info("MTRR: Disabled\n") has been executed in
early boot? If yes, this might be a BIOS option.


Juergen




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