[Patch v4 0/7] acpi,memory-hotplug : implement framework for hot removing memory

[Patch v4 0/7] acpi,memory-hotplug : implement framework for hot removing memory

[Wen Congyang]

The memory device can be removed by 2 ways:
1. send eject request by SCI
2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject

In the 1st case, acpi_memory_disable_device() will be called.
In the 2nd case, acpi_memory_device_remove() will be called.
acpi_memory_device_remove() will also be called when we unbind the
memory device from the driver acpi_memhotplug or a driver initialization
fails.

acpi_memory_disable_device() has already implemented a code which
offlines memory and releases acpi_memory_info struct . But
acpi_memory_device_remove() has not implemented it yet.

So the patch prepares the framework for hot removing memory and
adds the framework into acpi_memory_device_remove().

The last version of this patchset is here:
https://lkml.org/lkml/2012/10/26/175

Note: patch1-2 are in pm tree now. And there is a bug in patch1, so I resend
them. The commit in pm tree is:
patch1: 85fcb3758c10e063a2a30dfad75017097999deed
patch2: d0fbb400b6f3a6191bdc5024f8733b2e2b86338f

Changes from v3 to v4:
1. patch1: unlock list_lock when removing memory fails.
2. patch2: just rebase them
3. patch3-7: these patches are in -mm tree, and they conflict with this
   patchset, so Adrew Morton drop them from -mm tree. I rebase and merge
   them into this patchset.

Wen Congyang (6):
  acpi,memory-hotplug: introduce a mutex lock to protect the list in
    acpi_memory_device
  acpi_memhotplug.c: fix memory leak when memory device is unbound from
    the module acpi_memhotplug
  acpi_memhotplug.c: free memory device if acpi_memory_enable_device()
    failed
  acpi_memhotplug.c: don't allow to eject the memory device if it is
    being used
  acpi_memhotplug.c: bind the memory device when the driver is being
    loaded
  acpi_memhotplug.c: auto bind the memory device which is hotplugged
    before the driver is loaded

Yasuaki Ishimatsu (1):
  acpi,memory-hotplug : add memory offline code to
    acpi_memory_device_remove()

 drivers/acpi/acpi_memhotplug.c | 168 ++++++++++++++++++++++++++++++++---------
 1 file changed, 133 insertions(+), 35 deletions(-)

-- 
1.8.0

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[Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device

[Wen Congyang]

The memory device can be removed by 2 ways:
1. send eject request by SCI
2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject

This 2 events may happen at the same time, so we may touch
acpi_memory_device.res_list at the same time. This patch
introduce a lock to protect this list.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 The commit in pm tree is 85fcb375
 drivers/acpi/acpi_memhotplug.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 1e90e8f..4c18ee3 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -83,7 +83,8 @@ struct acpi_memory_info {
 struct acpi_memory_device {
 	struct acpi_device * device;
 	unsigned int state;	/* State of the memory device */
-	struct list_head res_list;
+	struct mutex list_lock;
+	struct list_head res_list;	/* protected by list_lock */
 };
 
 static int acpi_hotmem_initialized;
@@ -101,19 +102,23 @@ acpi_memory_get_resource(struct acpi_resource *resource, void *context)
 	    (address64.resource_type != ACPI_MEMORY_RANGE))
 		return AE_OK;
 
+	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry(info, &mem_device->res_list, list) {
 		/* Can we combine the resource range information? */
 		if ((info->caching == address64.info.mem.caching) &&
 		    (info->write_protect == address64.info.mem.write_protect) &&
 		    (info->start_addr + info->length == address64.minimum)) {
 			info->length += address64.address_length;
+			mutex_unlock(&mem_device->list_lock);
 			return AE_OK;
 		}
 	}
 
 	new = kzalloc(sizeof(struct acpi_memory_info), GFP_KERNEL);
-	if (!new)
+	if (!new) {
+		mutex_unlock(&mem_device->list_lock);
 		return AE_ERROR;
+	}
 
 	INIT_LIST_HEAD(&new->list);
 	new->caching = address64.info.mem.caching;
@@ -121,6 +126,7 @@ acpi_memory_get_resource(struct acpi_resource *resource, void *context)
 	new->start_addr = address64.minimum;
 	new->length = address64.address_length;
 	list_add_tail(&new->list, &mem_device->res_list);
+	mutex_unlock(&mem_device->list_lock);
 
 	return AE_OK;
 }
@@ -138,9 +144,11 @@ acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
 	status = acpi_walk_resources(mem_device->device->handle, METHOD_NAME__CRS,
 				     acpi_memory_get_resource, mem_device);
 	if (ACPI_FAILURE(status)) {
+		mutex_lock(&mem_device->list_lock);
 		list_for_each_entry_safe(info, n, &mem_device->res_list, list)
 			kfree(info);
 		INIT_LIST_HEAD(&mem_device->res_list);
+		mutex_unlock(&mem_device->list_lock);
 		return -EINVAL;
 	}
 
@@ -236,6 +244,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 	 * We don't have memory-hot-add rollback function,now.
 	 * (i.e. memory-hot-remove function)
 	 */
+	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry(info, &mem_device->res_list, list) {
 		if (info->enabled) { /* just sanity check...*/
 			num_enabled++;
@@ -256,6 +265,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 		info->enabled = 1;
 		num_enabled++;
 	}
+	mutex_unlock(&mem_device->list_lock);
 	if (!num_enabled) {
 		printk(KERN_ERR PREFIX "add_memory failed\n");
 		mem_device->state = MEMORY_INVALID_STATE;
@@ -316,14 +326,18 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
 	 * Ask the VM to offline this memory range.
 	 * Note: Assume that this function returns zero on success
 	 */
+	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (info->enabled) {
 			result = remove_memory(info->start_addr, info->length);
-			if (result)
+			if (result) {
+				mutex_unlock(&mem_device->list_lock);
 				return result;
+			}
 		}
 		kfree(info);
 	}
+	mutex_unlock(&mem_device->list_lock);
 
 	/* Power-off and eject the device */
 	result = acpi_memory_powerdown_device(mem_device);
@@ -438,6 +452,7 @@ static int acpi_memory_device_add(struct acpi_device *device)
 	mem_device->device = device;
 	sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
 	sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
+	mutex_init(&mem_device->list_lock);
 	device->driver_data = mem_device;
 
 	/* Get the range from the _CRS */
-- 
1.8.0

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Re: [Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device

[Toshi Kani]

On Thu, 2012-11-08 at 19:04 +0800, Wen Congyang wrote:
> The memory device can be removed by 2 ways:
> 1. send eject request by SCI
> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
> 
> This 2 events may happen at the same time, so we may touch
> acpi_memory_device.res_list at the same time. This patch
> introduce a lock to protect this list.

Hi Wen,

This race condition is not unique in memory hot-remove as the sysfs
eject interface is created for all objects with _EJ0.  For CPU
hot-remove, I addressed this race condition by making the notify handler
to run the hot-remove operation on kacpi_hotplug_wq by calling
acpi_os_hotplug_execute().  This serializes the hot-remove operations
among the two events since the sysfs eject also runs on
kacpi_hotplug_wq.  This way is much simpler and is easy to maintain,
although it does not allow both operations to run simultaneously (which
I do not think we need).  Can it be used for memory hot-remove as well?

Thanks,
-Toshi

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Re: [Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device

[Wen Congyang]

At 11/13/2012 05:00 AM, Toshi Kani Wrote:
> On Thu, 2012-11-08 at 19:04 +0800, Wen Congyang wrote:
>> The memory device can be removed by 2 ways:
>> 1. send eject request by SCI
>> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
>>
>> This 2 events may happen at the same time, so we may touch
>> acpi_memory_device.res_list at the same time. This patch
>> introduce a lock to protect this list.
> 
> Hi Wen,
> 
> This race condition is not unique in memory hot-remove as the sysfs
> eject interface is created for all objects with _EJ0.  For CPU
> hot-remove, I addressed this race condition by making the notify handler
> to run the hot-remove operation on kacpi_hotplug_wq by calling
> acpi_os_hotplug_execute().  This serializes the hot-remove operations
> among the two events since the sysfs eject also runs on
> kacpi_hotplug_wq.  This way is much simpler and is easy to maintain,
> although it does not allow both operations to run simultaneously (which
> I do not think we need).  Can it be used for memory hot-remove as well?

Good idea. I will update it.

Thanks
Wen Congyang

> 
> Thanks,
> -Toshi
> 
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Re: [Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device

[Rafael J. Wysocki]

On Tuesday, November 13, 2012 10:04:53 AM Wen Congyang wrote:
> At 11/13/2012 05:00 AM, Toshi Kani Wrote:
> > On Thu, 2012-11-08 at 19:04 +0800, Wen Congyang wrote:
> >> The memory device can be removed by 2 ways:
> >> 1. send eject request by SCI
> >> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
> >>
> >> This 2 events may happen at the same time, so we may touch
> >> acpi_memory_device.res_list at the same time. This patch
> >> introduce a lock to protect this list.
> > 
> > Hi Wen,
> > 
> > This race condition is not unique in memory hot-remove as the sysfs
> > eject interface is created for all objects with _EJ0.  For CPU
> > hot-remove, I addressed this race condition by making the notify handler
> > to run the hot-remove operation on kacpi_hotplug_wq by calling
> > acpi_os_hotplug_execute().  This serializes the hot-remove operations
> > among the two events since the sysfs eject also runs on
> > kacpi_hotplug_wq.  This way is much simpler and is easy to maintain,
> > although it does not allow both operations to run simultaneously (which
> > I do not think we need).  Can it be used for memory hot-remove as well?
> 
> Good idea. I will update it.

Still waiting. :-)

But if you want that in v3.8, please repost ASAP.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

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Re: [Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device

[Wen Congyang]

At 11/15/2012 07:34 AM, Rafael J. Wysocki Wrote:
> On Tuesday, November 13, 2012 10:04:53 AM Wen Congyang wrote:
>> At 11/13/2012 05:00 AM, Toshi Kani Wrote:
>>> On Thu, 2012-11-08 at 19:04 +0800, Wen Congyang wrote:
>>>> The memory device can be removed by 2 ways:
>>>> 1. send eject request by SCI
>>>> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
>>>>
>>>> This 2 events may happen at the same time, so we may touch
>>>> acpi_memory_device.res_list at the same time. This patch
>>>> introduce a lock to protect this list.
>>>
>>> Hi Wen,
>>>
>>> This race condition is not unique in memory hot-remove as the sysfs
>>> eject interface is created for all objects with _EJ0.  For CPU
>>> hot-remove, I addressed this race condition by making the notify handler
>>> to run the hot-remove operation on kacpi_hotplug_wq by calling
>>> acpi_os_hotplug_execute().  This serializes the hot-remove operations
>>> among the two events since the sysfs eject also runs on
>>> kacpi_hotplug_wq.  This way is much simpler and is easy to maintain,
>>> although it does not allow both operations to run simultaneously (which
>>> I do not think we need).  Can it be used for memory hot-remove as well?
>>
>> Good idea. I will update it.
> 
> Still waiting. :-)
> 
> But if you want that in v3.8, please repost ASAP.

I think I will send it today. It is in test now.

Thanks
Wen Congyang

> 
> Thanks,
> Rafael
> 
> 

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[Patch v4 2/7] acpi,memory-hotplug : add memory offline code to acpi_memory_device_remove()

[Wen Congyang]

From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

The memory device can be removed by 2 ways:
1. send eject request by SCI
2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject

In the 1st case, acpi_memory_disable_device() will be called.
In the 2nd case, acpi_memory_device_remove() will be called.
acpi_memory_device_remove() will also be called when we unbind the
memory device from the driver acpi_memhotplug or a driver initialization
fails.

acpi_memory_disable_device() has already implemented a code which
offlines memory and releases acpi_memory_info struct. But
acpi_memory_device_remove() has not implemented it yet.

So the patch move offlining memory and releasing acpi_memory_info struct
codes to a new function acpi_memory_remove_memory(). And it is used by both
acpi_memory_device_remove() and acpi_memory_disable_device().

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 The commit for pm tree is d0fbb400
 drivers/acpi/acpi_memhotplug.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 4c18ee3..e573e87 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -316,16 +316,11 @@ static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
 	return 0;
 }
 
-static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
+static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
 	int result;
 	struct acpi_memory_info *info, *n;
 
-
-	/*
-	 * Ask the VM to offline this memory range.
-	 * Note: Assume that this function returns zero on success
-	 */
 	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (info->enabled) {
@@ -335,10 +330,27 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
 				return result;
 			}
 		}
+
+		list_del(&info->list);
 		kfree(info);
 	}
 	mutex_unlock(&mem_device->list_lock);
 
+	return 0;
+}
+
+static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
+{
+	int result;
+
+	/*
+	 * Ask the VM to offline this memory range.
+	 * Note: Assume that this function returns zero on success
+	 */
+	result = acpi_memory_remove_memory(mem_device);
+	if (result)
+		return result;
+
 	/* Power-off and eject the device */
 	result = acpi_memory_powerdown_device(mem_device);
 	if (result) {
@@ -489,12 +501,17 @@ static int acpi_memory_device_add(struct acpi_device *device)
 static int acpi_memory_device_remove(struct acpi_device *device, int type)
 {
 	struct acpi_memory_device *mem_device = NULL;
-
+	int result;
 
 	if (!device || !acpi_driver_data(device))
 		return -EINVAL;
 
 	mem_device = acpi_driver_data(device);
+
+	result = acpi_memory_remove_memory(mem_device);
+	if (result)
+		return result;
+
 	kfree(mem_device);
 
 	return 0;
-- 
1.8.0

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[Patch v4 3/7] acpi_memhotplug.c: fix memory leak when memory device is unbound from the module acpi_memhotplug

[Wen Congyang]

We allocate memory to store acpi_memory_info, so we should free it before
freeing mem_device.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index e573e87..5e5ac80 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -131,12 +131,22 @@ acpi_memory_get_resource(struct acpi_resource *resource, void *context)
 	return AE_OK;
 }
 
+static void
+acpi_memory_free_device_resources(struct acpi_memory_device *mem_device)
+{
+	struct acpi_memory_info *info, *n;
+
+	mutex_lock(&mem_device->list_lock);
+	list_for_each_entry_safe(info, n, &mem_device->res_list, list)
+		kfree(info);
+	INIT_LIST_HEAD(&mem_device->res_list);
+	mutex_unlock(&mem_device->list_lock);
+}
+
 static int
 acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
 {
 	acpi_status status;
-	struct acpi_memory_info *info, *n;
-
 
 	if (!list_empty(&mem_device->res_list))
 		return 0;
@@ -144,11 +154,7 @@ acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
 	status = acpi_walk_resources(mem_device->device->handle, METHOD_NAME__CRS,
 				     acpi_memory_get_resource, mem_device);
 	if (ACPI_FAILURE(status)) {
-		mutex_lock(&mem_device->list_lock);
-		list_for_each_entry_safe(info, n, &mem_device->res_list, list)
-			kfree(info);
-		INIT_LIST_HEAD(&mem_device->res_list);
-		mutex_unlock(&mem_device->list_lock);
+		acpi_memory_free_device_resources(mem_device);
 		return -EINVAL;
 	}
 
@@ -447,6 +453,15 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
 	return;
 }
 
+static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
+{
+	if (!mem_device)
+		return;
+
+	acpi_memory_free_device_resources(mem_device);
+	kfree(mem_device);
+}
+
 static int acpi_memory_device_add(struct acpi_device *device)
 {
 	int result;
@@ -512,7 +527,7 @@ static int acpi_memory_device_remove(struct acpi_device *device, int type)
 	if (result)
 		return result;
 
-	kfree(mem_device);
+	acpi_memory_device_free(mem_device);
 
 	return 0;
 }
-- 
1.8.0

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[Patch v4 4/7] acpi_memhotplug.c: free memory device if acpi_memory_enable_device() failed

[Wen Congyang]

If acpi_memory_enable_device() fails, acpi_memory_enable_device() will
return a non-zero value, which means we fail to bind the memory device to
this driver.  So we should free memory device before
acpi_memory_device_add() returns.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 5e5ac80..8914399 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -506,9 +506,11 @@ static int acpi_memory_device_add(struct acpi_device *device)
 	if (!acpi_memory_check_device(mem_device)) {
 		/* call add_memory func */
 		result = acpi_memory_enable_device(mem_device);
-		if (result)
+		if (result) {
 			printk(KERN_ERR PREFIX
 				"Error in acpi_memory_enable_device\n");
+			acpi_memory_device_free(mem_device);
+		}
 	}
 	return result;
 }
-- 
1.8.0

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[Patch v4 5/7] acpi_memhotplug.c: don't allow to eject the memory device if it is being used

[Wen Congyang]

We eject the memory device even if it is in use.  It is very dangerous,
and it will cause the kernel to be panicked.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 46 +++++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 8914399..1fb1342 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -78,6 +78,7 @@ struct acpi_memory_info {
 	unsigned short caching;	/* memory cache attribute */
 	unsigned short write_protect;	/* memory read/write attribute */
 	unsigned int enabled:1;
+	unsigned int failed:1;
 };
 
 struct acpi_memory_device {
@@ -266,9 +267,23 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 			node = memory_add_physaddr_to_nid(info->start_addr);
 
 		result = add_memory(node, info->start_addr, info->length);
-		if (result)
+
+		/*
+		 * If the memory block has been used by the kernel, add_memory()
+		 * returns -EEXIST. If add_memory() returns the other error, it
+		 * means that this memory block is not used by the kernel.
+		 */
+		if (result && result != -EEXIST) {
+			info->failed = 1;
 			continue;
-		info->enabled = 1;
+		}
+
+		if (!result)
+			info->enabled = 1;
+		/*
+		 * Add num_enable even if add_memory() returns -EEXIST, so the
+		 * device is bound to this driver.
+		 */
 		num_enabled++;
 	}
 	mutex_unlock(&mem_device->list_lock);
@@ -324,25 +339,36 @@ static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
 
 static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
-	int result;
+	int result = 0;
 	struct acpi_memory_info *info, *n;
 
 	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
-		if (info->enabled) {
-			result = remove_memory(info->start_addr, info->length);
-			if (result) {
-				mutex_unlock(&mem_device->list_lock);
-				return result;
-			}
+		if (info->failed)
+			/* The kernel does not use this memory block */
+			continue;
+
+		if (!info->enabled) {
+			/*
+			 * The kernel uses this memory block, but it may be not
+			 * managed by us.
+			 */
+			result = -EBUSY;
+			goto out;
 		}
 
+		result = remove_memory(info->start_addr, info->length);
+		if (result)
+			goto out;
+
 		list_del(&info->list);
 		kfree(info);
 	}
+
+out:
 	mutex_unlock(&mem_device->list_lock);
 
-	return 0;
+	return result;
 }
 
 static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
-- 
1.8.0

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[Patch v4 6/7] acpi_memhotplug.c: bind the memory device when the driver is being loaded

[Wen Congyang]

We had introduced acpi_hotmem_initialized to avoid strange add_memory fail
message.  But the memory device may not be used by the kernel, and the
device should be bound when the driver is being loaded.  Remove
acpi_hotmem_initialized to allow that the device can be bound when the
driver is being loaded.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 1fb1342..8a8716f 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -88,8 +88,6 @@ struct acpi_memory_device {
 	struct list_head res_list;	/* protected by list_lock */
 };
 
-static int acpi_hotmem_initialized;
-
 static acpi_status
 acpi_memory_get_resource(struct acpi_resource *resource, void *context)
 {
@@ -520,15 +518,6 @@ static int acpi_memory_device_add(struct acpi_device *device)
 
 	printk(KERN_DEBUG "%s \n", acpi_device_name(device));
 
-	/*
-	 * Early boot code has recognized memory area by EFI/E820.
-	 * If DSDT shows these memory devices on boot, hotplug is not necessary
-	 * for them. So, it just returns until completion of this driver's
-	 * start up.
-	 */
-	if (!acpi_hotmem_initialized)
-		return 0;
-
 	if (!acpi_memory_check_device(mem_device)) {
 		/* call add_memory func */
 		result = acpi_memory_enable_device(mem_device);
@@ -644,7 +633,6 @@ static int __init acpi_memory_device_init(void)
 		return -ENODEV;
 	}
 
-	acpi_hotmem_initialized = 1;
 	return 0;
 }
 
-- 
1.8.0

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[Patch v4 7/7] acpi_memhotplug.c: auto bind the memory device which is hotplugged before the driver is loaded

[Wen Congyang]

If the memory device is hotplugged before the driver is loaded, the user
cannot see this device under the directory /sys/bus/acpi/devices/, and the
user cannot bind it by hand after the driver is loaded.  This patch
introduces a new feature to bind such device when the driver is being
loaded.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 8a8716f..24bfa6e 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -52,6 +52,9 @@ MODULE_LICENSE("GPL");
 #define MEMORY_POWER_ON_STATE	1
 #define MEMORY_POWER_OFF_STATE	2
 
+static bool auto_probe;
+module_param(auto_probe, bool, S_IRUGO | S_IWUSR);
+
 static int acpi_memory_device_add(struct acpi_device *device);
 static int acpi_memory_device_remove(struct acpi_device *device, int type);
 
@@ -581,12 +584,44 @@ acpi_memory_register_notify_handler(acpi_handle handle,
 				    u32 level, void *ctxt, void **retv)
 {
 	acpi_status status;
-
+	struct acpi_memory_device *mem_device = NULL;
+	unsigned long long current_status;
 
 	status = is_memory_device(handle);
 	if (ACPI_FAILURE(status))
 		return AE_OK;	/* continue */
 
+	if (auto_probe) {
+		/* Get device present/absent information from the _STA */
+		status = acpi_evaluate_integer(handle, "_STA", NULL,
+					       &current_status);
+		if (ACPI_FAILURE(status))
+			goto install;
+
+		/*
+		 * Check for device status. Device should be
+		 * present/enabled/functioning.
+		 */
+		if (!(current_status &
+		      (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED |
+		       ACPI_STA_DEVICE_FUNCTIONING)))
+			goto install;
+
+		if (acpi_memory_get_device(handle, &mem_device))
+			goto install;
+
+		/* We have bound this device while we register the driver */
+		if (mem_device->state == MEMORY_POWER_ON_STATE)
+			goto install;
+
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+				  "\nauto probe memory device\n"));
+
+		if (acpi_memory_enable_device(mem_device))
+			pr_err(PREFIX "Cannot enable memory device\n");
+	}
+
+install:
 	status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
 					     acpi_memory_device_notify, NULL);
 	/* continue */
-- 
1.8.0

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