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

Dave Hansen
2017-11-27T16:14:35Z

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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.

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---

b/drivers/acpi/osl.c | 4 ++++
1 file changed, 4 insertions(+)

diff -puN drivers/acpi/osl.c~acpi-off-but-still-called drivers/acpi/osl.c
--- a/drivers/acpi/osl.c~acpi-off-but-still-called 2017-11-27 08:05:53.161611164 -0800
+++ b/drivers/acpi/osl.c 2017-11-27 08:06:55.288611009 -0800
@@ -191,6 +191,8 @@ acpi_physical_address __init acpi_os_get
{
acpi_physical_address pa = 0;

+ if (acpi_disabled)
+ return pa;
#ifdef CONFIG_KEXEC
if (acpi_rsdp)
return acpi_rsdp;
@@ -318,6 +320,8 @@ acpi_os_map_iomem(acpi_physical_address
acpi_physical_address pg_off;
acpi_size pg_sz;

+ WARN_ON(acpi_disabled);
+
if (phys > ULONG_MAX) {
printk(KERN_ERR PREFIX "Cannot map memory that high\n");
return NULL;
_