On Tuesday, April 07, 2015 01:22:52 PM Rafael J. Wysocki wrote:
> On Tuesday, April 07, 2015 05:03:12 PM Xie XiuQi wrote:
> > I meet a deadlock during cpu hotplug. The code path is bellow:
> >
> > Call Trace:
> > [<ffffffff816e373c>] dump_stack+0x19/0x1b
> > [<ffffffff810fd85a>] validate_chain.isra.43+0xf4a/0x1120
> > [<ffffffff810236c9>] ? sched_clock+0x9/0x10
> > [<ffffffff810ca8bd>] ? sched_clock_local+0x1d/0x80
> > [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff810fe846>] __lock_acquire+0x3c6/0xb70
> > [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
> > [<ffffffff810ff7e2>] lock_acquire+0xa2/0x1f0
> > [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> > [<ffffffff816e7a14>] mutex_lock_nested+0x94/0x3f0
> > [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> > [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> > [<ffffffff810fe0fd>] ? trace_hardirqs_on+0xd/0x10
> > [<ffffffff813ba132>] acpi_scan_is_offline+0x2c/0xa3 --> LOCK (DEADLOCK)
>
> Is it the same device, actually? acpi_container_offline() walks the *children*
> of the container while acpi_bus_offline() locks the container itself.
So the patch below should make the splat go away too if I'm not mistaken.
---
drivers/acpi/scan.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
struct acpi_device_physical_node *pn;
bool offline = true;
- mutex_lock(&adev->physical_node_lock);
+ /*
+ * acpi_container_offline() calls this for all of the container's
+ * children under the container's physical_node_lock lock.
+ */
+ mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
list_for_each_entry(pn, &adev->physical_node_list, node)
if (device_supports_offline(pn->dev) && !pn->dev->offline) {
--
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