linux-kernel - Re: KASLR causes intermittent boot failures on some systems

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Date:   Fri, 07 Apr 2017 10:51:21 -0400
From:   Jeff Moyer <jmoyer@...hat.com>
To:     Thomas Garnier <thgarnie@...gle.com>
Cc:     Ingo Molnar <mingo@...nel.org>, Baoquan He <bhe@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-nvdimm@...ts.01.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: KASLR causes intermittent boot failures on some systems

Thomas Garnier <thgarnie@...gle.com> writes:

> CCing Kees for information.
>
> On Fri, Apr 7, 2017 at 7:41 AM, Jeff Moyer <jmoyer@...hat.com> wrote:
>> Hi,
>>
>> commit 021182e52fe01 ("x86/mm: Enable KASLR for physical mapping memory
>> regions") causes some of my systems with persistent memory (whether real
>> or emulated) to fail to boot with a couple of different crash
>> signatures.  The first signature is a NMI watchdog lockup of all but 1
>> cpu, which causes much difficulty in extracting useful information from
>> the console.  The second variant is an invalid paging request, listed
>> below.
>>
>> On some systems, I haven't hit this problem at all.  Other systems
>> experience a failed boot maybe 20-30% of the time.  To reproduce it,
>> configure some emulated pmem on your system.  You can find directions
>> for that here: https://nvdimm.wiki.kernel.org/
>
> Did you try to repro on qemu?

I did not.

-Jeff