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authorIngo Molnar <mingo@elte.hu>2007-02-13 13:26:24 +0100
committerAndi Kleen <andi@basil.nowhere.org>2007-02-13 13:26:24 +0100
commit5d0e600d903caa09e790824cc5812f0d97113b23 (patch)
treea9650a9a77d6aa394e98d766aef67ac14666ccc6 /drivers/acpi/namespace
parent310adfdd9153f6ae818981a38a48dd2330990d8d (diff)
[PATCH] x86: fix laptop bootup hang in init_acpi()
During kernel bootup, a new T60 laptop (CoreDuo, 32-bit) hangs about 10%-20% of the time in acpi_init(): Calling initcall 0xc055ce1a: topology_init+0x0/0x2f() Calling initcall 0xc055d75e: mtrr_init_finialize+0x0/0x2c() Calling initcall 0xc05664f3: param_sysfs_init+0x0/0x175() Calling initcall 0xc014cb65: pm_sysrq_init+0x0/0x17() Calling initcall 0xc0569f99: init_bio+0x0/0xf4() Calling initcall 0xc056b865: genhd_device_init+0x0/0x50() Calling initcall 0xc056c4bd: fbmem_init+0x0/0x87() Calling initcall 0xc056dd74: acpi_init+0x0/0x1ee() It's a hard hang that not even an NMI could punch through! Frustratingly, adding printks or function tracing to the ACPI code made the hangs go away ... After some time an additional detail emerged: disabling the NMI watchdog made these occasional hangs go away. So i spent the better part of today trying to debug this and trying out various theories when i finally found the likely reason for the hang: if acpi_ns_initialize_devices() executes an _INI AML method and an NMI happens to hit that AML execution in the wrong moment, the machine would hang. (my theory is that this must be some sort of chipset setup method doing stores to chipset mmio registers?) Unfortunately given the characteristics of the hang it was sheer impossible to figure out which of the numerous AML methods is impacted by this problem. As a workaround i wrote an interface to disable chipset-based NMIs while executing _INI sections - and indeed this fixed the hang. I did a boot-loop of 100 separate reboots and none hung - while without the patch it would hang every 5-10 attempts. Out of caution i did not touch the nmi_watchdog=2 case (it's not related to the chipset anyway and didnt hang). I implemented this for both x86_64 and i686, tested the i686 laptop both with nmi_watchdog=1 [which triggered the hangs] and nmi_watchdog=2, and tested an Athlon64 box with the 64-bit kernel as well. Everything builds and works with the patch applied. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Andi Kleen <ak@suse.de> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/acpi/namespace')
-rw-r--r--drivers/acpi/namespace/nsinit.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/acpi/namespace/nsinit.c b/drivers/acpi/namespace/nsinit.c
index 326af8fc0ce..33db2241044 100644
--- a/drivers/acpi/namespace/nsinit.c
+++ b/drivers/acpi/namespace/nsinit.c
@@ -45,6 +45,7 @@
#include <acpi/acnamesp.h>
#include <acpi/acdispat.h>
#include <acpi/acinterp.h>
+#include <linux/nmi.h>
#define _COMPONENT ACPI_NAMESPACE
ACPI_MODULE_NAME("nsinit")
@@ -534,7 +535,15 @@ acpi_ns_init_one_device(acpi_handle obj_handle,
info->parameter_type = ACPI_PARAM_ARGS;
info->flags = ACPI_IGNORE_RETURN_VALUE;
+ /*
+ * Some hardware relies on this being executed as atomically
+ * as possible (without an NMI being received in the middle of
+ * this) - so disable NMIs and initialize the device:
+ */
+ acpi_nmi_disable();
status = acpi_ns_evaluate(info);
+ acpi_nmi_enable();
+
if (ACPI_SUCCESS(status)) {
walk_info->num_INI++;