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Subject: Re: [PATCH 4.4 103/105] Revert "x86/mm/pat: Ensure cpa->pfn only
 contains page frame numbers"
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Roland Dreier <roland@purestorage.com>,
        Ben Hutchings <ben.hutchings@codethink.co.uk>,
        LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
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        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>, luto@kernel.org,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>, bp@alien8.de,
        brgerst@gmail.com, davej@codemonkey.org.uk, dvlasenk@redhat.com,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        sai.praneeth.prakhya@intel.com, sds@tycho.nsa.gov,
        Thomas Gleixner <tglx@linutronix.de>, toshi.kani@hp.com,
        linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Yazen.Ghannam@amd.com
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From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <c2e61e43-6cd5-567a-8c3c-3cc3ff456c31@roeck-us.net>
Date:   Sat, 25 Aug 2018 19:30:53 -0700
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On 08/25/2018 08:07 AM, Greg Kroah-Hartman wrote:
> On Sat, Aug 25, 2018 at 06:52:32AM -0700, Guenter Roeck wrote:
>> Hi Roland,
>>
>> On 08/24/2018 01:04 PM, Roland Dreier wrote:
>>>> Ok, so what patch should be reverted?  I'm seeing other reports of
>>>> problems all around this same area, but I can't figure out exactly what
>>>> to do.
>>>
>>> Are any of those reports public?  If so can you point me at them, I'm
>>> curious if the symptoms match up.
>>>
>>> I don't think we want to revert anything.  I think you should pull in
>>> edc3b9129cec and at least the first three patches that Ben listed:
>>>
>>> 21cdb6b56843 x86/mm: Page align the '_end' symbol to avoid pfn conversion bugs
>>> b61a76f8850d x86/efi: Map RAM into the identity page table for mixed mode
>>> 753b11ef8e92 x86/efi: Setup separate EFI page tables in kexec paths
>>>
>>> the first patch takes a bit of massaging (mostly because some of it is
>>> already touched by 02ff2769edbc, which keeps the changes from
>>> edc3b9129cec, and so we can drop a good bit when applying).  The other
>>> three apply cleanly.
>>>
>>> I'm currently testing that and can send you the state of my tree in a bit.
>>>
>>
>> Have you made any progress ? On my side I am still out of luck since I can not
>> reproduce the problem.
> 
> Perhaps just the patch that Andi posted to the stable list helps out
> here?
> 

For reference:

https://www.spinics.net/lists/stable/msg253357.html

That would be the most straightforward and simple fix, so I would prefer
to go with it if it works.

Guenter