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Date:   Mon, 27 Nov 2017 08:14:35 -0800
From:   Dave Hansen <dave.hansen@...ux.intel.com>
To:     Ingo Molnar <mingo@...nel.org>,
        kernel test robot <fengguang.wu@...el.com>
Cc:     LKP <lkp@...org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        wfg@...ux.intel.com, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-acpi@...r.kernel.org, "Brown, Len" <len.brown@...el.com>,
        Jesse Barnes <jbarnes@...tuousgeek.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: 2f47e7e19f ("x86/mm/kaiser: Use PCID feature to make user and
 .."): WARNING: CPU: 0 PID: 1 at mm/early_ioremap.c:114 __early_ioremap

On 11/27/2017 02:18 AM, Ingo Molnar wrote:
> [    0.031000] Call Trace:
> [    0.031000]  ? kernfs_add_one+0x1d9/0x1f0
> [    0.031000]  early_memremap+0x33/0x3d
> [    0.031000]  ? cnb20le_res+0x2f2/0x2f2
> [    0.031000]  __acpi_map_table+0x1d/0x28
> [    0.031000]  acpi_os_map_iomem+0x1cf/0x2a0
> [    0.031000]  ? cnb20le_res+0x2f2/0x2f2
> [    0.031000]  acpi_os_map_memory+0xd/0x20
> [    0.031000]  acpi_find_root_pointer+0x1f/0x1ec
> [    0.031000]  ? cnb20le_res+0x2f2/0x2f2
> [    0.031000]  acpi_os_get_root_pointer+0x18/0x25
> [    0.031000]  broadcom_postcore_init+0xc/0x6c
> [    0.031000]  do_one_initcall+0xc4/0x1f7
> [    0.031000]  kernel_init_freeable+0x1c2/0x2b2
> [    0.031000]  ? rest_init+0x1a0/0x1a0
> [    0.031000]  kernel_init+0xd/0x1bc
> [    0.031000]  ret_from_fork+0x1f/0x30

I've been able to reproduce this.  The bug here (at least on my system)
is that we're calling into the ACPI code while 'acpi_disabled=1'.  The
ACPI code then notices that it hasn't been initialized (because it
should be off) and calls into the early_ioremap() code thinking that
it's in early boot.

I don't know why the bisect pinned this on the kaiser patches, or why
it's only showing up now.  It's possible that some botched TLB flush
_caused_ ACPI to get disabled at a weird time which then caused this
warning.

There are some recent changes around broadcom_postcore_init().

ACPI folks, any suggestions on what to do here?  Should we be bailing
out of acpi_os_get_root_pointer() like the attached patch?

It might also be worth an audit of all of the 'acpi_permanent_mmap'
call-sites to make sure they check acpi_disabled first.

View attachment "acpi-off-but-still-called.patch" of type "text/x-patch" (735 bytes)

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