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Subjectmmotm 2009-07-16-14-32 - sudden OOPS at boot in ACPI code
On Thu, 16 Jul 2009 14:34:02 PDT, said:
> The mm-of-the-moment snapshot 2009-07-16-14-32 has been uploaded to

Dies a horrid death during early boot. Dell Latitude D820, and this graphics:

01:00.0 VGA compatible controller: nVidia Corporation G72M [Quadro NVS 110M/GeForce Go 7300] (rev a1)

Traceback (hand-copied from a very crappy cell-phone picture)

? __driver_attach+0x58/0x7c
? __driver_attach+0x58/0x7c
? acpi_video_init+0x0/0x17

Analysis shows it's the following code from (inlined) acpi_device_install_notify_handler

static int acpi_device_install_notify_handler(struct acpi_device *device)
acpi_status status;
char *hid;

hid = acpi_device_hid(device);
if (!strcmp(hid, ACPI_BUTTON_HID_POWERF))

but we never check if hid is non-trash before feeding it to strcmp. Looks
like something in this linux-next commit is involved:

commit ed444824932d2a563858d82ec1ea29b0aa775e91
Author: Bob Moore <>
Date: Mon Jun 29 13:39:29 2009 +0800

I suspect something in acpi_get_object_info() is going astray, causing
acpi_device_set_id() to set the ->pnp.hardware_id to NULL in this code:

if (hid) {
device->pnp.hardware_id = ACPI_ALLOCATE_ZEROED(strlen (hid) + 1);
if (device->pnp.hardware_id) {
strcpy(device->pnp.hardware_id, hid);
device->flags.hardware_id = 1;
} else
device->pnp.hardware_id = NULL;

The else clause is new in this commit.

Looking at the old code, it *may* be that the ACPI code on my laptop is just
busticated and/or there's no _HID method for the graphics card, and the old
code Just Happened To Work in previous kernels because ->pnp.hardware_id
wouldn't actually get set *at all* in acpi_device_set_id, so we'd get random
stale data that was bogus, but didn't give strcmp() indigestion...

Any wisdom on debugging this further (including how to tell if the ACPI
tables have a sane _HID method for the graphics card) would be appreciated...

Or is the correct fix in fact to just add a 'if (!hid) return -EINVAL;' to

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