Patchwork [RFC,v2,4/13] memory-hotplug : remove /sys/firmware/memmap/X sysfs

login
register
mail settings
Submitter Yasuaki Ishimatsu
Date July 3, 2012, 5:56 a.m.
Message ID <4FF28996.10702@jp.fujitsu.com>
Download mbox | patch
Permalink /patch/168707/
State Not Applicable
Headers show

Comments

Yasuaki Ishimatsu - July 3, 2012, 5:56 a.m.
When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
sysfs files are created. But there is no code to remove these files. The patch
implements the function to remove them.

Note : The code does not free firmware_map_entry since there is no way to free
       memory which is allocated by bootmem.

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>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

---
 drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/firmware-map.h |    6 +++
 mm/memory_hotplug.c          |    6 +++
 3 files changed, 81 insertions(+), 1 deletion(-)
Wen Congyang - July 3, 2012, 6:35 a.m.
At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
> sysfs files are created. But there is no code to remove these files. The patch
> implements the function to remove them.
> 
> Note : The code does not free firmware_map_entry since there is no way to free
>        memory which is allocated by bootmem.
> 
> 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>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> 
> ---
>  drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/firmware-map.h |    6 +++
>  mm/memory_hotplug.c          |    6 +++
>  3 files changed, 81 insertions(+), 1 deletion(-)
> 
> Index: linux-3.5-rc4/mm/memory_hotplug.c
> ===================================================================
> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
> 
>  int remove_memory(int nid, u64 start, u64 size)
>  {
> -	return -EBUSY;
> +	lock_memory_hotplug();
> +	/* remove memmap entry */
> +	firmware_map_remove(start, start + size - 1, "System RAM");
> +	unlock_memory_hotplug();
> +	return 0;
> 
>  }
>  EXPORT_SYMBOL_GPL(remove_memory);
> Index: linux-3.5-rc4/include/linux/firmware-map.h
> ===================================================================
> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
> @@ -25,6 +25,7 @@
> 
>  int firmware_map_add_early(u64 start, u64 end, const char *type);
>  int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
> +int firmware_map_remove(u64 start, u64 end, const char *type);
> 
>  #else /* CONFIG_FIRMWARE_MEMMAP */
> 
> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>  	return 0;
>  }
> 
> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
> +{
> +	return 0;
> +}
> +
>  #endif /* CONFIG_FIRMWARE_MEMMAP */
> 
>  #endif /* _LINUX_FIRMWARE_MAP_H */
> Index: linux-3.5-rc4/drivers/firmware/memmap.c
> ===================================================================
> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>  	.show = memmap_attr_show,
>  };
> 
> +static void release_firmware_map_entry(struct kobject *kobj)
> +{
> +	/*
> +	 * FIXME : There is no idea.
> +	 *         How to free the entry which allocated bootmem?
> +	 */

I find a function free_bootmem(), but I am not sure whether it can work here.
Another problem: how to check whether the entry uses bootmem?

Thanks
Wen Congyang

> +}
> +
>  static struct kobj_type memmap_ktype = {
> +	.release	= release_firmware_map_entry,
>  	.sysfs_ops	= &memmap_attr_ops,
>  	.default_attrs	= def_attrs,
>  };
> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>  	return 0;
>  }
> 
> +/**
> + * firmware_map_remove_entry() - Does the real work to remove a firmware
> + * memmap entry.
> + * @entry: removed entry.
> + **/
> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
> +{
> +	list_del(&entry->list);
> +}
> +
>  /*
>   * Add memmap entry on sysfs
>   */
> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>  	return 0;
>  }
> 
> +/*
> + * Remove memmap entry on sysfs
> + */
> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
> +{
> +	kobject_put(&entry->kobj);
> +}
> +
> +/*
> + * Search memmap entry
> + */
> +
> +struct firmware_map_entry * __meminit
> +find_firmware_map_entry(u64 start, u64 end, const char *type)
> +{
> +	struct firmware_map_entry *entry;
> +
> +	list_for_each_entry(entry, &map_entries, list)
> +		if ((entry->start == start) && (entry->end == end) &&
> +		    (!strcmp(entry->type, type)))
> +			return entry;
> +
> +	return NULL;
> +}
> +
>  /**
>   * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>   * memory hotplug.
> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>  	return firmware_map_add_entry(start, end, type, entry);
>  }
> 
> +/**
> + * firmware_map_remove() - remove a firmware mapping entry
> + * @start: Start of the memory range.
> + * @end:   End of the memory range (inclusive).
> + * @type:  Type of the memory range.
> + *
> + * removes a firmware mapping entry.
> + *
> + * Returns 0 on success, or -EINVAL if no entry.
> + **/
> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
> +{
> +	struct firmware_map_entry *entry;
> +
> +	entry = find_firmware_map_entry(start, end, type);
> +	if (!entry)
> +		return -EINVAL;
> +
> +	/* remove the memmap entry */
> +	remove_sysfs_fw_map_entry(entry);
> +
> +	firmware_map_remove_entry(entry);
> +
> +	return 0;
> +}
> +
>  /*
>   * Sysfs functions -------------------------------------------------------------
>   */
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
Yasuaki Ishimatsu - July 4, 2012, 4:45 a.m.
Hi Wen,

2012/07/03 15:35, Wen Congyang wrote:
> At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
>> sysfs files are created. But there is no code to remove these files. The patch
>> implements the function to remove them.
>>
>> Note : The code does not free firmware_map_entry since there is no way to free
>>         memory which is allocated by bootmem.
>>
>> 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>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>
>> ---
>>   drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/firmware-map.h |    6 +++
>>   mm/memory_hotplug.c          |    6 +++
>>   3 files changed, 81 insertions(+), 1 deletion(-)
>>
>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>> ===================================================================
>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
>>
>>   int remove_memory(int nid, u64 start, u64 size)
>>   {
>> -	return -EBUSY;
>> +	lock_memory_hotplug();
>> +	/* remove memmap entry */
>> +	firmware_map_remove(start, start + size - 1, "System RAM");
>> +	unlock_memory_hotplug();
>> +	return 0;
>>
>>   }
>>   EXPORT_SYMBOL_GPL(remove_memory);
>> Index: linux-3.5-rc4/include/linux/firmware-map.h
>> ===================================================================
>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
>> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
>> @@ -25,6 +25,7 @@
>>
>>   int firmware_map_add_early(u64 start, u64 end, const char *type);
>>   int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
>> +int firmware_map_remove(u64 start, u64 end, const char *type);
>>
>>   #else /* CONFIG_FIRMWARE_MEMMAP */
>>
>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>>   	return 0;
>>   }
>>
>> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
>> +{
>> +	return 0;
>> +}
>> +
>>   #endif /* CONFIG_FIRMWARE_MEMMAP */
>>
>>   #endif /* _LINUX_FIRMWARE_MAP_H */
>> Index: linux-3.5-rc4/drivers/firmware/memmap.c
>> ===================================================================
>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
>> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>>   	.show = memmap_attr_show,
>>   };
>>
>> +static void release_firmware_map_entry(struct kobject *kobj)
>> +{
>> +	/*
>> +	 * FIXME : There is no idea.
>> +	 *         How to free the entry which allocated bootmem?
>> +	 */
> 
> I find a function free_bootmem(), but I am not sure whether it can work here.

It cannot work here.

> Another problem: how to check whether the entry uses bootmem?

When firmware_map_entry is allocated by kzalloc(), the page has PG_slab.
So we can check whether the entry was allocated by bootmem or not.
If the eantry was allocated by kzalloc(), we can free the entry by kfree().
But if the entry was allocated by bootmem, we have no way to free the entry.

Thanks,
Yasuaki Ishimatsu

> 
> Thanks
> Wen Congyang
> 
>> +}
>> +
>>   static struct kobj_type memmap_ktype = {
>> +	.release	= release_firmware_map_entry,
>>   	.sysfs_ops	= &memmap_attr_ops,
>>   	.default_attrs	= def_attrs,
>>   };
>> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>>   	return 0;
>>   }
>>
>> +/**
>> + * firmware_map_remove_entry() - Does the real work to remove a firmware
>> + * memmap entry.
>> + * @entry: removed entry.
>> + **/
>> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
>> +{
>> +	list_del(&entry->list);
>> +}
>> +
>>   /*
>>    * Add memmap entry on sysfs
>>    */
>> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>>   	return 0;
>>   }
>>
>> +/*
>> + * Remove memmap entry on sysfs
>> + */
>> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
>> +{
>> +	kobject_put(&entry->kobj);
>> +}
>> +
>> +/*
>> + * Search memmap entry
>> + */
>> +
>> +struct firmware_map_entry * __meminit
>> +find_firmware_map_entry(u64 start, u64 end, const char *type)
>> +{
>> +	struct firmware_map_entry *entry;
>> +
>> +	list_for_each_entry(entry, &map_entries, list)
>> +		if ((entry->start == start) && (entry->end == end) &&
>> +		    (!strcmp(entry->type, type)))
>> +			return entry;
>> +
>> +	return NULL;
>> +}
>> +
>>   /**
>>    * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>>    * memory hotplug.
>> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>>   	return firmware_map_add_entry(start, end, type, entry);
>>   }
>>
>> +/**
>> + * firmware_map_remove() - remove a firmware mapping entry
>> + * @start: Start of the memory range.
>> + * @end:   End of the memory range (inclusive).
>> + * @type:  Type of the memory range.
>> + *
>> + * removes a firmware mapping entry.
>> + *
>> + * Returns 0 on success, or -EINVAL if no entry.
>> + **/
>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
>> +{
>> +	struct firmware_map_entry *entry;
>> +
>> +	entry = find_firmware_map_entry(start, end, type);
>> +	if (!entry)
>> +		return -EINVAL;
>> +
>> +	/* remove the memmap entry */
>> +	remove_sysfs_fw_map_entry(entry);
>> +
>> +	firmware_map_remove_entry(entry);
>> +
>> +	return 0;
>> +}
>> +
>>   /*
>>    * Sysfs functions -------------------------------------------------------------
>>    */
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
Wen Congyang - July 4, 2012, 5:08 a.m.
At 07/04/2012 12:45 PM, Yasuaki Ishimatsu Wrote:
> Hi Wen,
> 
> 2012/07/03 15:35, Wen Congyang wrote:
>> At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
>>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
>>> sysfs files are created. But there is no code to remove these files. The patch
>>> implements the function to remove them.
>>>
>>> Note : The code does not free firmware_map_entry since there is no way to free
>>>         memory which is allocated by bootmem.
>>>
>>> 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>
>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>>
>>> ---
>>>   drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>>>   include/linux/firmware-map.h |    6 +++
>>>   mm/memory_hotplug.c          |    6 +++
>>>   3 files changed, 81 insertions(+), 1 deletion(-)
>>>
>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
>>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
>>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
>>>
>>>   int remove_memory(int nid, u64 start, u64 size)
>>>   {
>>> -	return -EBUSY;
>>> +	lock_memory_hotplug();
>>> +	/* remove memmap entry */
>>> +	firmware_map_remove(start, start + size - 1, "System RAM");
>>> +	unlock_memory_hotplug();
>>> +	return 0;
>>>
>>>   }
>>>   EXPORT_SYMBOL_GPL(remove_memory);
>>> Index: linux-3.5-rc4/include/linux/firmware-map.h
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
>>> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
>>> @@ -25,6 +25,7 @@
>>>
>>>   int firmware_map_add_early(u64 start, u64 end, const char *type);
>>>   int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
>>> +int firmware_map_remove(u64 start, u64 end, const char *type);
>>>
>>>   #else /* CONFIG_FIRMWARE_MEMMAP */
>>>
>>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>>>   	return 0;
>>>   }
>>>
>>> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
>>> +{
>>> +	return 0;
>>> +}
>>> +
>>>   #endif /* CONFIG_FIRMWARE_MEMMAP */
>>>
>>>   #endif /* _LINUX_FIRMWARE_MAP_H */
>>> Index: linux-3.5-rc4/drivers/firmware/memmap.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
>>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>>>   	.show = memmap_attr_show,
>>>   };
>>>
>>> +static void release_firmware_map_entry(struct kobject *kobj)
>>> +{
>>> +	/*
>>> +	 * FIXME : There is no idea.
>>> +	 *         How to free the entry which allocated bootmem?
>>> +	 */
>>
>> I find a function free_bootmem(), but I am not sure whether it can work here.
> 
> It cannot work here.
> 
>> Another problem: how to check whether the entry uses bootmem?
> 
> When firmware_map_entry is allocated by kzalloc(), the page has PG_slab.

This is not true. In my test, I find the page does not have PG_slab sometimes.

Thanks
Wen Congyang.

> So we can check whether the entry was allocated by bootmem or not.
> If the eantry was allocated by kzalloc(), we can free the entry by kfree().
> But if the entry was allocated by bootmem, we have no way to free the entry.
> 
> Thanks,
> Yasuaki Ishimatsu
> 
>>
>> Thanks
>> Wen Congyang
>>
>>> +}
>>> +
>>>   static struct kobj_type memmap_ktype = {
>>> +	.release	= release_firmware_map_entry,
>>>   	.sysfs_ops	= &memmap_attr_ops,
>>>   	.default_attrs	= def_attrs,
>>>   };
>>> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>>>   	return 0;
>>>   }
>>>
>>> +/**
>>> + * firmware_map_remove_entry() - Does the real work to remove a firmware
>>> + * memmap entry.
>>> + * @entry: removed entry.
>>> + **/
>>> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
>>> +{
>>> +	list_del(&entry->list);
>>> +}
>>> +
>>>   /*
>>>    * Add memmap entry on sysfs
>>>    */
>>> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>>>   	return 0;
>>>   }
>>>
>>> +/*
>>> + * Remove memmap entry on sysfs
>>> + */
>>> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
>>> +{
>>> +	kobject_put(&entry->kobj);
>>> +}
>>> +
>>> +/*
>>> + * Search memmap entry
>>> + */
>>> +
>>> +struct firmware_map_entry * __meminit
>>> +find_firmware_map_entry(u64 start, u64 end, const char *type)
>>> +{
>>> +	struct firmware_map_entry *entry;
>>> +
>>> +	list_for_each_entry(entry, &map_entries, list)
>>> +		if ((entry->start == start) && (entry->end == end) &&
>>> +		    (!strcmp(entry->type, type)))
>>> +			return entry;
>>> +
>>> +	return NULL;
>>> +}
>>> +
>>>   /**
>>>    * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>>>    * memory hotplug.
>>> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>>>   	return firmware_map_add_entry(start, end, type, entry);
>>>   }
>>>
>>> +/**
>>> + * firmware_map_remove() - remove a firmware mapping entry
>>> + * @start: Start of the memory range.
>>> + * @end:   End of the memory range (inclusive).
>>> + * @type:  Type of the memory range.
>>> + *
>>> + * removes a firmware mapping entry.
>>> + *
>>> + * Returns 0 on success, or -EINVAL if no entry.
>>> + **/
>>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
>>> +{
>>> +	struct firmware_map_entry *entry;
>>> +
>>> +	entry = find_firmware_map_entry(start, end, type);
>>> +	if (!entry)
>>> +		return -EINVAL;
>>> +
>>> +	/* remove the memmap entry */
>>> +	remove_sysfs_fw_map_entry(entry);
>>> +
>>> +	firmware_map_remove_entry(entry);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>   /*
>>>    * Sysfs functions -------------------------------------------------------------
>>>    */
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
> 
> 
> 
>
Yasuaki Ishimatsu - July 4, 2012, 5:52 a.m.
Hi Wen,

2012/07/04 14:08, Wen Congyang wrote:
> At 07/04/2012 12:45 PM, Yasuaki Ishimatsu Wrote:
>> Hi Wen,
>>
>> 2012/07/03 15:35, Wen Congyang wrote:
>>> At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
>>>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
>>>> sysfs files are created. But there is no code to remove these files. The patch
>>>> implements the function to remove them.
>>>>
>>>> Note : The code does not free firmware_map_entry since there is no way to free
>>>>          memory which is allocated by bootmem.
>>>>
>>>> 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>
>>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>>>
>>>> ---
>>>>    drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>>>>    include/linux/firmware-map.h |    6 +++
>>>>    mm/memory_hotplug.c          |    6 +++
>>>>    3 files changed, 81 insertions(+), 1 deletion(-)
>>>>
>>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>>> ===================================================================
>>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
>>>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
>>>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
>>>>
>>>>    int remove_memory(int nid, u64 start, u64 size)
>>>>    {
>>>> -	return -EBUSY;
>>>> +	lock_memory_hotplug();
>>>> +	/* remove memmap entry */
>>>> +	firmware_map_remove(start, start + size - 1, "System RAM");
>>>> +	unlock_memory_hotplug();
>>>> +	return 0;
>>>>
>>>>    }
>>>>    EXPORT_SYMBOL_GPL(remove_memory);
>>>> Index: linux-3.5-rc4/include/linux/firmware-map.h
>>>> ===================================================================
>>>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
>>>> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
>>>> @@ -25,6 +25,7 @@
>>>>
>>>>    int firmware_map_add_early(u64 start, u64 end, const char *type);
>>>>    int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
>>>> +int firmware_map_remove(u64 start, u64 end, const char *type);
>>>>
>>>>    #else /* CONFIG_FIRMWARE_MEMMAP */
>>>>
>>>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>>>>    	return 0;
>>>>    }
>>>>
>>>> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
>>>> +{
>>>> +	return 0;
>>>> +}
>>>> +
>>>>    #endif /* CONFIG_FIRMWARE_MEMMAP */
>>>>
>>>>    #endif /* _LINUX_FIRMWARE_MAP_H */
>>>> Index: linux-3.5-rc4/drivers/firmware/memmap.c
>>>> ===================================================================
>>>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
>>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
>>>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>>>>    	.show = memmap_attr_show,
>>>>    };
>>>>
>>>> +static void release_firmware_map_entry(struct kobject *kobj)
>>>> +{
>>>> +	/*
>>>> +	 * FIXME : There is no idea.
>>>> +	 *         How to free the entry which allocated bootmem?
>>>> +	 */
>>>
>>> I find a function free_bootmem(), but I am not sure whether it can work here.
>>
>> It cannot work here.
>>
>>> Another problem: how to check whether the entry uses bootmem?
>>
>> When firmware_map_entry is allocated by kzalloc(), the page has PG_slab.
> 
> This is not true. In my test, I find the page does not have PG_slab sometimes.

I think that it depends on the allocated size. firmware_map_entry size is
smaller than PAGE_SIZE. So the page has PG_Slab.

Thanks,
Yasuaki Ishimatsu

> 
> Thanks
> Wen Congyang.
> 
>> So we can check whether the entry was allocated by bootmem or not.
>> If the eantry was allocated by kzalloc(), we can free the entry by kfree().
>> But if the entry was allocated by bootmem, we have no way to free the entry.
>>
>> Thanks,
>> Yasuaki Ishimatsu
>>
>>>
>>> Thanks
>>> Wen Congyang
>>>
>>>> +}
>>>> +
>>>>    static struct kobj_type memmap_ktype = {
>>>> +	.release	= release_firmware_map_entry,
>>>>    	.sysfs_ops	= &memmap_attr_ops,
>>>>    	.default_attrs	= def_attrs,
>>>>    };
>>>> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>>>>    	return 0;
>>>>    }
>>>>
>>>> +/**
>>>> + * firmware_map_remove_entry() - Does the real work to remove a firmware
>>>> + * memmap entry.
>>>> + * @entry: removed entry.
>>>> + **/
>>>> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
>>>> +{
>>>> +	list_del(&entry->list);
>>>> +}
>>>> +
>>>>    /*
>>>>     * Add memmap entry on sysfs
>>>>     */
>>>> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>>>>    	return 0;
>>>>    }
>>>>
>>>> +/*
>>>> + * Remove memmap entry on sysfs
>>>> + */
>>>> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
>>>> +{
>>>> +	kobject_put(&entry->kobj);
>>>> +}
>>>> +
>>>> +/*
>>>> + * Search memmap entry
>>>> + */
>>>> +
>>>> +struct firmware_map_entry * __meminit
>>>> +find_firmware_map_entry(u64 start, u64 end, const char *type)
>>>> +{
>>>> +	struct firmware_map_entry *entry;
>>>> +
>>>> +	list_for_each_entry(entry, &map_entries, list)
>>>> +		if ((entry->start == start) && (entry->end == end) &&
>>>> +		    (!strcmp(entry->type, type)))
>>>> +			return entry;
>>>> +
>>>> +	return NULL;
>>>> +}
>>>> +
>>>>    /**
>>>>     * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>>>>     * memory hotplug.
>>>> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>>>>    	return firmware_map_add_entry(start, end, type, entry);
>>>>    }
>>>>
>>>> +/**
>>>> + * firmware_map_remove() - remove a firmware mapping entry
>>>> + * @start: Start of the memory range.
>>>> + * @end:   End of the memory range (inclusive).
>>>> + * @type:  Type of the memory range.
>>>> + *
>>>> + * removes a firmware mapping entry.
>>>> + *
>>>> + * Returns 0 on success, or -EINVAL if no entry.
>>>> + **/
>>>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
>>>> +{
>>>> +	struct firmware_map_entry *entry;
>>>> +
>>>> +	entry = find_firmware_map_entry(start, end, type);
>>>> +	if (!entry)
>>>> +		return -EINVAL;
>>>> +
>>>> +	/* remove the memmap entry */
>>>> +	remove_sysfs_fw_map_entry(entry);
>>>> +
>>>> +	firmware_map_remove_entry(entry);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>    /*
>>>>     * Sysfs functions -------------------------------------------------------------
>>>>     */
>>>>
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>>> the body of a message to majordomo@vger.kernel.org
>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>>
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>
>>
>>
>>
>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
Wen Congyang - July 4, 2012, 10:01 a.m.
At 07/04/2012 01:52 PM, Yasuaki Ishimatsu Wrote:
> Hi Wen,
> 
> 2012/07/04 14:08, Wen Congyang wrote:
>> At 07/04/2012 12:45 PM, Yasuaki Ishimatsu Wrote:
>>> Hi Wen,
>>>
>>> 2012/07/03 15:35, Wen Congyang wrote:
>>>> At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
>>>>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
>>>>> sysfs files are created. But there is no code to remove these files. The patch
>>>>> implements the function to remove them.
>>>>>
>>>>> Note : The code does not free firmware_map_entry since there is no way to free
>>>>>          memory which is allocated by bootmem.
>>>>>
>>>>> 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>
>>>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>>>>
>>>>> ---
>>>>>    drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>>>>>    include/linux/firmware-map.h |    6 +++
>>>>>    mm/memory_hotplug.c          |    6 +++
>>>>>    3 files changed, 81 insertions(+), 1 deletion(-)
>>>>>
>>>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>>>> ===================================================================
>>>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
>>>>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
>>>>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
>>>>>
>>>>>    int remove_memory(int nid, u64 start, u64 size)
>>>>>    {
>>>>> -	return -EBUSY;
>>>>> +	lock_memory_hotplug();
>>>>> +	/* remove memmap entry */
>>>>> +	firmware_map_remove(start, start + size - 1, "System RAM");
>>>>> +	unlock_memory_hotplug();
>>>>> +	return 0;
>>>>>
>>>>>    }
>>>>>    EXPORT_SYMBOL_GPL(remove_memory);
>>>>> Index: linux-3.5-rc4/include/linux/firmware-map.h
>>>>> ===================================================================
>>>>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
>>>>> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
>>>>> @@ -25,6 +25,7 @@
>>>>>
>>>>>    int firmware_map_add_early(u64 start, u64 end, const char *type);
>>>>>    int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
>>>>> +int firmware_map_remove(u64 start, u64 end, const char *type);
>>>>>
>>>>>    #else /* CONFIG_FIRMWARE_MEMMAP */
>>>>>
>>>>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>>>>>    	return 0;
>>>>>    }
>>>>>
>>>>> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
>>>>> +{
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>    #endif /* CONFIG_FIRMWARE_MEMMAP */
>>>>>
>>>>>    #endif /* _LINUX_FIRMWARE_MAP_H */
>>>>> Index: linux-3.5-rc4/drivers/firmware/memmap.c
>>>>> ===================================================================
>>>>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
>>>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
>>>>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>>>>>    	.show = memmap_attr_show,
>>>>>    };
>>>>>
>>>>> +static void release_firmware_map_entry(struct kobject *kobj)
>>>>> +{
>>>>> +	/*
>>>>> +	 * FIXME : There is no idea.
>>>>> +	 *         How to free the entry which allocated bootmem?
>>>>> +	 */
>>>>
>>>> I find a function free_bootmem(), but I am not sure whether it can work here.
>>>
>>> It cannot work here.
>>>
>>>> Another problem: how to check whether the entry uses bootmem?
>>>
>>> When firmware_map_entry is allocated by kzalloc(), the page has PG_slab.
>>
>> This is not true. In my test, I find the page does not have PG_slab sometimes.
> 
> I think that it depends on the allocated size. firmware_map_entry size is
> smaller than PAGE_SIZE. So the page has PG_Slab.

In my test, I add printk in the function firmware_map_add_hotplug() to display
page's flags. And sometimes the page is not allocated by slab(I use PageSlab()
to verify it).

Thanks
Wen Congyang

> 
> Thanks,
> Yasuaki Ishimatsu
> 
>>
>> Thanks
>> Wen Congyang.
>>
>>> So we can check whether the entry was allocated by bootmem or not.
>>> If the eantry was allocated by kzalloc(), we can free the entry by kfree().
>>> But if the entry was allocated by bootmem, we have no way to free the entry.
>>>
>>> Thanks,
>>> Yasuaki Ishimatsu
>>>
>>>>
>>>> Thanks
>>>> Wen Congyang
>>>>
>>>>> +}
>>>>> +
>>>>>    static struct kobj_type memmap_ktype = {
>>>>> +	.release	= release_firmware_map_entry,
>>>>>    	.sysfs_ops	= &memmap_attr_ops,
>>>>>    	.default_attrs	= def_attrs,
>>>>>    };
>>>>> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>>>>>    	return 0;
>>>>>    }
>>>>>
>>>>> +/**
>>>>> + * firmware_map_remove_entry() - Does the real work to remove a firmware
>>>>> + * memmap entry.
>>>>> + * @entry: removed entry.
>>>>> + **/
>>>>> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
>>>>> +{
>>>>> +	list_del(&entry->list);
>>>>> +}
>>>>> +
>>>>>    /*
>>>>>     * Add memmap entry on sysfs
>>>>>     */
>>>>> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>>>>>    	return 0;
>>>>>    }
>>>>>
>>>>> +/*
>>>>> + * Remove memmap entry on sysfs
>>>>> + */
>>>>> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
>>>>> +{
>>>>> +	kobject_put(&entry->kobj);
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * Search memmap entry
>>>>> + */
>>>>> +
>>>>> +struct firmware_map_entry * __meminit
>>>>> +find_firmware_map_entry(u64 start, u64 end, const char *type)
>>>>> +{
>>>>> +	struct firmware_map_entry *entry;
>>>>> +
>>>>> +	list_for_each_entry(entry, &map_entries, list)
>>>>> +		if ((entry->start == start) && (entry->end == end) &&
>>>>> +		    (!strcmp(entry->type, type)))
>>>>> +			return entry;
>>>>> +
>>>>> +	return NULL;
>>>>> +}
>>>>> +
>>>>>    /**
>>>>>     * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>>>>>     * memory hotplug.
>>>>> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>>>>>    	return firmware_map_add_entry(start, end, type, entry);
>>>>>    }
>>>>>
>>>>> +/**
>>>>> + * firmware_map_remove() - remove a firmware mapping entry
>>>>> + * @start: Start of the memory range.
>>>>> + * @end:   End of the memory range (inclusive).
>>>>> + * @type:  Type of the memory range.
>>>>> + *
>>>>> + * removes a firmware mapping entry.
>>>>> + *
>>>>> + * Returns 0 on success, or -EINVAL if no entry.
>>>>> + **/
>>>>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
>>>>> +{
>>>>> +	struct firmware_map_entry *entry;
>>>>> +
>>>>> +	entry = find_firmware_map_entry(start, end, type);
>>>>> +	if (!entry)
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	/* remove the memmap entry */
>>>>> +	remove_sysfs_fw_map_entry(entry);
>>>>> +
>>>>> +	firmware_map_remove_entry(entry);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>    /*
>>>>>     * Sysfs functions -------------------------------------------------------------
>>>>>     */
>>>>>
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>>>> the body of a message to majordomo@vger.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>>>
>>>>
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>>> the body of a message to majordomo@vger.kernel.org
>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>>
>>>
>>>
>>>
>>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
> 
> 
> 
>
Yasuaki Ishimatsu - July 6, 2012, 8:27 a.m.
Hi Wen,

2012/07/04 19:01, Wen Congyang wrote:
> At 07/04/2012 01:52 PM, Yasuaki Ishimatsu Wrote:
>> Hi Wen,
>>
>> 2012/07/04 14:08, Wen Congyang wrote:
>>> At 07/04/2012 12:45 PM, Yasuaki Ishimatsu Wrote:
>>>> Hi Wen,
>>>>
>>>> 2012/07/03 15:35, Wen Congyang wrote:
>>>>> At 07/03/2012 01:56 PM, Yasuaki Ishimatsu Wrote:
>>>>>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
>>>>>> sysfs files are created. But there is no code to remove these files. The patch
>>>>>> implements the function to remove them.
>>>>>>
>>>>>> Note : The code does not free firmware_map_entry since there is no way to free
>>>>>>           memory which is allocated by bootmem.
>>>>>>
>>>>>> 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>
>>>>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>>>>>
>>>>>> ---
>>>>>>     drivers/firmware/memmap.c    |   70 +++++++++++++++++++++++++++++++++++++++++++
>>>>>>     include/linux/firmware-map.h |    6 +++
>>>>>>     mm/memory_hotplug.c          |    6 +++
>>>>>>     3 files changed, 81 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>>>>> ===================================================================
>>>>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
>>>>>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
>>>>>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);
>>>>>>
>>>>>>     int remove_memory(int nid, u64 start, u64 size)
>>>>>>     {
>>>>>> -	return -EBUSY;
>>>>>> +	lock_memory_hotplug();
>>>>>> +	/* remove memmap entry */
>>>>>> +	firmware_map_remove(start, start + size - 1, "System RAM");
>>>>>> +	unlock_memory_hotplug();
>>>>>> +	return 0;
>>>>>>
>>>>>>     }
>>>>>>     EXPORT_SYMBOL_GPL(remove_memory);
>>>>>> Index: linux-3.5-rc4/include/linux/firmware-map.h
>>>>>> ===================================================================
>>>>>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
>>>>>> +++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
>>>>>> @@ -25,6 +25,7 @@
>>>>>>
>>>>>>     int firmware_map_add_early(u64 start, u64 end, const char *type);
>>>>>>     int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
>>>>>> +int firmware_map_remove(u64 start, u64 end, const char *type);
>>>>>>
>>>>>>     #else /* CONFIG_FIRMWARE_MEMMAP */
>>>>>>
>>>>>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl
>>>>>>     	return 0;
>>>>>>     }
>>>>>>
>>>>>> +static inline int firmware_map_remove(u64 start, u64 end, const char *type)
>>>>>> +{
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>>     #endif /* CONFIG_FIRMWARE_MEMMAP */
>>>>>>
>>>>>>     #endif /* _LINUX_FIRMWARE_MAP_H */
>>>>>> Index: linux-3.5-rc4/drivers/firmware/memmap.c
>>>>>> ===================================================================
>>>>>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
>>>>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
>>>>>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att
>>>>>>     	.show = memmap_attr_show,
>>>>>>     };
>>>>>>
>>>>>> +static void release_firmware_map_entry(struct kobject *kobj)
>>>>>> +{
>>>>>> +	/*
>>>>>> +	 * FIXME : There is no idea.
>>>>>> +	 *         How to free the entry which allocated bootmem?
>>>>>> +	 */
>>>>>
>>>>> I find a function free_bootmem(), but I am not sure whether it can work here.
>>>>
>>>> It cannot work here.
>>>>
>>>>> Another problem: how to check whether the entry uses bootmem?
>>>>
>>>> When firmware_map_entry is allocated by kzalloc(), the page has PG_slab.
>>>
>>> This is not true. In my test, I find the page does not have PG_slab sometimes.
>>
>> I think that it depends on the allocated size. firmware_map_entry size is
>> smaller than PAGE_SIZE. So the page has PG_Slab.
> 
> In my test, I add printk in the function firmware_map_add_hotplug() to display
> page's flags. And sometimes the page is not allocated by slab(I use PageSlab()
> to verify it).

How did you check it? Could you send your debug patch?

Thanks,
Yasuaki Ishimatsu

> Thanks
> Wen Congyang
> 
>>
>> Thanks,
>> Yasuaki Ishimatsu
>>
>>>
>>> Thanks
>>> Wen Congyang.
>>>
>>>> So we can check whether the entry was allocated by bootmem or not.
>>>> If the eantry was allocated by kzalloc(), we can free the entry by kfree().
>>>> But if the entry was allocated by bootmem, we have no way to free the entry.
>>>>
>>>> Thanks,
>>>> Yasuaki Ishimatsu
>>>>
>>>>>
>>>>> Thanks
>>>>> Wen Congyang
>>>>>
>>>>>> +}
>>>>>> +
>>>>>>     static struct kobj_type memmap_ktype = {
>>>>>> +	.release	= release_firmware_map_entry,
>>>>>>     	.sysfs_ops	= &memmap_attr_ops,
>>>>>>     	.default_attrs	= def_attrs,
>>>>>>     };
>>>>>> @@ -123,6 +132,16 @@ static int firmware_map_add_entry(u64 st
>>>>>>     	return 0;
>>>>>>     }
>>>>>>
>>>>>> +/**
>>>>>> + * firmware_map_remove_entry() - Does the real work to remove a firmware
>>>>>> + * memmap entry.
>>>>>> + * @entry: removed entry.
>>>>>> + **/
>>>>>> +static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
>>>>>> +{
>>>>>> +	list_del(&entry->list);
>>>>>> +}
>>>>>> +
>>>>>>     /*
>>>>>>      * Add memmap entry on sysfs
>>>>>>      */
>>>>>> @@ -144,6 +163,31 @@ static int add_sysfs_fw_map_entry(struct
>>>>>>     	return 0;
>>>>>>     }
>>>>>>
>>>>>> +/*
>>>>>> + * Remove memmap entry on sysfs
>>>>>> + */
>>>>>> +static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
>>>>>> +{
>>>>>> +	kobject_put(&entry->kobj);
>>>>>> +}
>>>>>> +
>>>>>> +/*
>>>>>> + * Search memmap entry
>>>>>> + */
>>>>>> +
>>>>>> +struct firmware_map_entry * __meminit
>>>>>> +find_firmware_map_entry(u64 start, u64 end, const char *type)
>>>>>> +{
>>>>>> +	struct firmware_map_entry *entry;
>>>>>> +
>>>>>> +	list_for_each_entry(entry, &map_entries, list)
>>>>>> +		if ((entry->start == start) && (entry->end == end) &&
>>>>>> +		    (!strcmp(entry->type, type)))
>>>>>> +			return entry;
>>>>>> +
>>>>>> +	return NULL;
>>>>>> +}
>>>>>> +
>>>>>>     /**
>>>>>>      * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
>>>>>>      * memory hotplug.
>>>>>> @@ -196,6 +240,32 @@ int __init firmware_map_add_early(u64 st
>>>>>>     	return firmware_map_add_entry(start, end, type, entry);
>>>>>>     }
>>>>>>
>>>>>> +/**
>>>>>> + * firmware_map_remove() - remove a firmware mapping entry
>>>>>> + * @start: Start of the memory range.
>>>>>> + * @end:   End of the memory range (inclusive).
>>>>>> + * @type:  Type of the memory range.
>>>>>> + *
>>>>>> + * removes a firmware mapping entry.
>>>>>> + *
>>>>>> + * Returns 0 on success, or -EINVAL if no entry.
>>>>>> + **/
>>>>>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
>>>>>> +{
>>>>>> +	struct firmware_map_entry *entry;
>>>>>> +
>>>>>> +	entry = find_firmware_map_entry(start, end, type);
>>>>>> +	if (!entry)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	/* remove the memmap entry */
>>>>>> +	remove_sysfs_fw_map_entry(entry);
>>>>>> +
>>>>>> +	firmware_map_remove_entry(entry);
>>>>>> +
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>>     /*
>>>>>>      * Sysfs functions -------------------------------------------------------------
>>>>>>      */
>>>>>>
>>>>>> --
>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>>>>> the body of a message to majordomo@vger.kernel.org
>>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>>>>
>>>>>
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>>>> the body of a message to majordomo@vger.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>
>>
>>
>>
>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

Patch

Index: linux-3.5-rc4/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-07-03 14:22:00.190240794 +0900
+++ linux-3.5-rc4/mm/memory_hotplug.c	2012-07-03 14:22:03.549198802 +0900
@@ -661,7 +661,11 @@  EXPORT_SYMBOL_GPL(add_memory);

 int remove_memory(int nid, u64 start, u64 size)
 {
-	return -EBUSY;
+	lock_memory_hotplug();
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size - 1, "System RAM");
+	unlock_memory_hotplug();
+	return 0;

 }
 EXPORT_SYMBOL_GPL(remove_memory);
Index: linux-3.5-rc4/include/linux/firmware-map.h
===================================================================
--- linux-3.5-rc4.orig/include/linux/firmware-map.h	2012-07-03 14:21:45.766421116 +0900
+++ linux-3.5-rc4/include/linux/firmware-map.h	2012-07-03 14:22:03.550198789 +0900
@@ -25,6 +25,7 @@ 

 int firmware_map_add_early(u64 start, u64 end, const char *type);
 int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
+int firmware_map_remove(u64 start, u64 end, const char *type);

 #else /* CONFIG_FIRMWARE_MEMMAP */

@@ -38,6 +39,11 @@  static inline int firmware_map_add_hotpl
 	return 0;
 }

+static inline int firmware_map_remove(u64 start, u64 end, const char *type)
+{
+	return 0;
+}
+
 #endif /* CONFIG_FIRMWARE_MEMMAP */

 #endif /* _LINUX_FIRMWARE_MAP_H */
Index: linux-3.5-rc4/drivers/firmware/memmap.c
===================================================================
--- linux-3.5-rc4.orig/drivers/firmware/memmap.c	2012-07-03 14:21:45.761421180 +0900
+++ linux-3.5-rc4/drivers/firmware/memmap.c	2012-07-03 14:22:03.569198549 +0900
@@ -79,7 +79,16 @@  static const struct sysfs_ops memmap_att
 	.show = memmap_attr_show,
 };

+static void release_firmware_map_entry(struct kobject *kobj)
+{
+	/*
+	 * FIXME : There is no idea.
+	 *         How to free the entry which allocated bootmem?
+	 */
+}
+
 static struct kobj_type memmap_ktype = {
+	.release	= release_firmware_map_entry,
 	.sysfs_ops	= &memmap_attr_ops,
 	.default_attrs	= def_attrs,
 };
@@ -123,6 +132,16 @@  static int firmware_map_add_entry(u64 st
 	return 0;
 }

+/**
+ * firmware_map_remove_entry() - Does the real work to remove a firmware
+ * memmap entry.
+ * @entry: removed entry.
+ **/
+static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
+{
+	list_del(&entry->list);
+}
+
 /*
  * Add memmap entry on sysfs
  */
@@ -144,6 +163,31 @@  static int add_sysfs_fw_map_entry(struct
 	return 0;
 }

+/*
+ * Remove memmap entry on sysfs
+ */
+static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
+{
+	kobject_put(&entry->kobj);
+}
+
+/*
+ * Search memmap entry
+ */
+
+struct firmware_map_entry * __meminit
+find_firmware_map_entry(u64 start, u64 end, const char *type)
+{
+	struct firmware_map_entry *entry;
+
+	list_for_each_entry(entry, &map_entries, list)
+		if ((entry->start == start) && (entry->end == end) &&
+		    (!strcmp(entry->type, type)))
+			return entry;
+
+	return NULL;
+}
+
 /**
  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
  * memory hotplug.
@@ -196,6 +240,32 @@  int __init firmware_map_add_early(u64 st
 	return firmware_map_add_entry(start, end, type, entry);
 }

+/**
+ * firmware_map_remove() - remove a firmware mapping entry
+ * @start: Start of the memory range.
+ * @end:   End of the memory range (inclusive).
+ * @type:  Type of the memory range.
+ *
+ * removes a firmware mapping entry.
+ *
+ * Returns 0 on success, or -EINVAL if no entry.
+ **/
+int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
+{
+	struct firmware_map_entry *entry;
+
+	entry = find_firmware_map_entry(start, end, type);
+	if (!entry)
+		return -EINVAL;
+
+	/* remove the memmap entry */
+	remove_sysfs_fw_map_entry(entry);
+
+	firmware_map_remove_entry(entry);
+
+	return 0;
+}
+
 /*
  * Sysfs functions -------------------------------------------------------------
  */