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)
[<ffffffff813fdac8>] acpi_container_offline+0x32/0x4e
[<ffffffff81469e59>] container_offline+0x19/0x20
[<ffffffff81462955>] device_offline+0x95/0xc0
[<ffffffff813b9e53>] acpi_bus_offline+0xbc/0x126 --> LOCK
[<ffffffff813bb83d>] acpi_device_hotplug+0x236/0x46b
[<ffffffff813b4c75>] acpi_hotplug_work_fn+0x1e/0x29
[<ffffffff810a6c10>] process_one_work+0x220/0x710
[<ffffffff810a6ba4>] ? process_one_work+0x1b4/0x710
[<ffffffff810a721b>] worker_thread+0x11b/0x3a0
[<ffffffff810a7100>] ? process_one_work+0x710/0x710
[<ffffffff810b061d>] kthread+0xed/0x100
[<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
[<ffffffff816f663c>] ret_from_fork+0x7c/0xb0
[<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
This deadlock was introduced by commit caa73ea
("ACPI / hotplug / driver core: Handle containers in a special way").
In this patch, we just introduced a lockless version __acpi_scan_is_offline()
for acpi_container_offline(), to avoid this deadlock.
Cc: <stable@xxxxxxxxxxxxxxx> # v3.14+
Signed-off-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
---
drivers/acpi/container.c | 2 +-
drivers/acpi/internal.h | 1 +
drivers/acpi/scan.c | 15 ++++++++++++---
3 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index c8ead9f..43bda3b2 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -50,7 +50,7 @@ static int acpi_container_offline(struct container_dev *cdev)
/* Check all of the dependent devices' physical companions. */
list_for_each_entry(child, &adev->children, node)
- if (!acpi_scan_is_offline(child, false))
+ if (!__acpi_scan_is_offline(child, false))
return -EBUSY;
return 0;
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 56b321a..3b7a07b 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -80,6 +80,7 @@ void acpi_apd_init(void);
acpi_status acpi_hotplug_schedule(struct acpi_device *adev, u32 src);
bool acpi_queue_hotplug_work(struct work_struct *work);
void acpi_device_hotplug(struct acpi_device *adev, u32 src);
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
/* --------------------------------------------------------------------------
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bbca783..ea55a9a 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -293,13 +293,12 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
-bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+/* Must be called under physical_node_lock. */
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
{
struct acpi_device_physical_node *pn;
bool offline = true;
- mutex_lock(&adev->physical_node_lock);
-
list_for_each_entry(pn, &adev->physical_node_list, node)
if (device_supports_offline(pn->dev) && !pn->dev->offline) {
if (uevent)
@@ -309,7 +308,17 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
break;
}
+ return offline;
+}
+
+bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+{
+ bool offline = true;
+
+ mutex_lock(&adev->physical_node_lock);
+ offline = __acpi_scan_is_offline(adev, uevent);
mutex_unlock(&adev->physical_node_lock);
+
return offline;
}
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
