linux-kernel - [BUG] GPF on reboot of box

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Date:   Fri, 6 Oct 2017 21:39:56 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Nadav Amit <nadav.amit@...il.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [BUG] GPF on reboot of box

Starting with v4.14-rc1 my box crashes during a reboot. All I get is
the following:

[  250.615793] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[  250.635639] reboot: Restarting system
[  250.639671] reboot: machine restart
[  250.643842] general protection fault: 0000 [#1] PREEMPT SMP KASAN

Then nothing. No reboot, it just hangs there.

I bisected it down to this commit:

660da7c9228f ("x86/mm: Enable CR4.PCIDE on supported systems")

If I comment out the setting of X86_CR4_PCIDE in that commit, it boots
fine. But...

I noticed that commit c7ad5ad29 ("x86/mm/64: Initialize CR4.PCIDE
early") moved the problem code from arch/x86/kernel/cpu/common.c to
arch/x86/mm/init.c

If I comment it out in v4.14-rc1, it crashes on boot up.

It appears that my box doesn't like having X86_CR4_PCIDE set. it causes
reboot to fail. But it also appears that setting that is required for
some other code to work.

Help!

-- Steve