Hi, Imre

> From: Deak, Imre
> Subject: Re: 4.9-rc1: [TMP_] ACPI namespace lookup failure, AE_ALREADY_EXISTS
> 
> On Fri, 2016-10-21 at 22:46 +0300, Zheng, Lv wrote:
> > [...]
> > I checked the code, only found one issue.
> > And I'm not sure if it is related.
> > Please send me the full dmesg containing the errors and the acpidump
> > output.
> 
> I attached the dmesg containing the error during boot (happened 1 out
> of 200 boots), during reboot (20 out of 200 reboots), during suspend
> (happened all the time).

I just checked the error and the related code.

1. What the error is
The error message is generated by an old method auto-serial mechanism.
However this mechanism should have been disabled by new auto-serial approach.

See: the error is generated by the code in drivers/acpi/acpica/psparse.c:
			if ((status == AE_ALREADY_EXISTS) &&
			    (!(walk_state->method_desc->method.
			       info_flags & ACPI_METHOD_SERIALIZED))) {
				/*
				 * Method is not serialized and tried to create an object
				 * twice. The probable cause is that the method cannot
				 * handle reentrancy. Mark as "pending serialized" now, and
				 * then mark "serialized" when the last thread exits.
				 */
				walk_state->method_desc->method.info_flags |=
				    ACPI_METHOD_SERIALIZED_PENDING;
			}
It can only happen when ACPI_METHOD_SERIALIZED flag is not set.
However, in the upstream kernel, this flag is set by the code in drivers/acpi/acpica/dsinit.c:
		if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
			info->serial_method_count++;
			break;
		}

		if (acpi_gbl_auto_serialize_methods) {

			/* Parse/scan method and serialize it if necessary */

			acpi_ds_auto_serialize_method(node, obj_desc);
			if (obj_desc->method.
			    info_flags & ACPI_METHOD_SERIALIZED) {

				/* Method was just converted to Serialized */

				info->serial_method_count++;
				info->serialized_method_count++;
				break;
			}
		}
Which is invoked by acpi_ds_initialize_objects(), always invoked in acpi_ns_load_table().
Unless acpi_gbl_auto_serialize_methods = false or acpi_ns_parse_table() failed, the flag won't be remained unset.

The error message is generated by old auto-serialize implementation.
And acpi_gbl_auto_serialize_methods is meant to mute the warnings.

Both mechanism should work, thus this error message is not fatal.
It just makes ACPICA to fall back to use old auto-serial method.
So the issue is not urgent.

2. Why the error message is caused
I couldn't see whether the bisected commit can be related to this feature.
It seems we need your help to debug what the problem is.

First, please try the mentioned branch here:
https://github.com/zetalog/linux
acpica-lock branch.

As I may need to ask for several debugging steps, let me file a kernel Bugzilla bug for this.
So that we can communicate there in order not to bother others:

https://bugzilla.kernel.org/show_bug.cgi?id=180111

Thanks and best regards
Lv


> 
> I attached the acpidump output.
> 
> > Please give the fix a try (see attachment).
> 
> The patch didn't apply on 4.9-rc1 or Linus' master, please see the
> attached patch for my attempt to resolve the conflicts. With the patch
> applied I could still trigger the same problem during suspend.
> 
> --Imre
> 
> > I'm sorry for sending fix patch using attachment.
> > It's not convenient for me due to my current working environment.
> >
> > Thanks and best regards
> > Lv