Patchwork [v5,04/14] memory-hotplug: remove /sys/firmware/memmap/X sysfs

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Submitter Tang Chen
Date Dec. 24, 2012, 12:09 p.m.
Message ID <1356350964-13437-5-git-send-email-tangchen@cn.fujitsu.com>
Download mbox | patch
Permalink /patch/208064/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Tang Chen - Dec. 24, 2012, 12:09 p.m.
From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

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 which is allocated by bootmem.
      So the patch makes memory leak. But I think the memory leak size is
      very samll. And it does not affect the system.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
 drivers/firmware/memmap.c    |   98 +++++++++++++++++++++++++++++++++++++++++-
 include/linux/firmware-map.h |    6 +++
 mm/memory_hotplug.c          |    5 ++-
 3 files changed, 106 insertions(+), 3 deletions(-)
KAMEZAWA Hiroyuki - Dec. 26, 2012, 3:30 a.m.
(2012/12/24 21:09), Tang Chen wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> 
> 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 which is allocated by bootmem.
>        So the patch makes memory leak. But I think the memory leak size is
>        very samll. And it does not affect the system.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> ---
>   drivers/firmware/memmap.c    |   98 +++++++++++++++++++++++++++++++++++++++++-
>   include/linux/firmware-map.h |    6 +++
>   mm/memory_hotplug.c          |    5 ++-
>   3 files changed, 106 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
> index 90723e6..49be12a 100644
> --- a/drivers/firmware/memmap.c
> +++ b/drivers/firmware/memmap.c
> @@ -21,6 +21,7 @@
>   #include <linux/types.h>
>   #include <linux/bootmem.h>
>   #include <linux/slab.h>
> +#include <linux/mm.h>
>   
>   /*
>    * Data types ------------------------------------------------------------------
> @@ -41,6 +42,7 @@ struct firmware_map_entry {
>   	const char		*type;	/* type of the memory range */
>   	struct list_head	list;	/* entry for the linked list */
>   	struct kobject		kobj;   /* kobject for each entry */
> +	unsigned int		bootmem:1; /* allocated from bootmem */
>   };

Can't we detect from which the object is allocated from, slab or bootmem ?

Hm, for example,

    PageReserved(virt_to_page(address_of_obj)) ?
    PageSlab(virt_to_page(address_of_obj)) ?

Thanks,
-Kame

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Tang Chen - Dec. 27, 2012, 3:09 a.m.
On 12/26/2012 11:30 AM, Kamezawa Hiroyuki wrote:
>> @@ -41,6 +42,7 @@ struct firmware_map_entry {
>>    	const char		*type;	/* type of the memory range */
>>    	struct list_head	list;	/* entry for the linked list */
>>    	struct kobject		kobj;   /* kobject for each entry */
>> +	unsigned int		bootmem:1; /* allocated from bootmem */
>>    };
> 
> Can't we detect from which the object is allocated from, slab or bootmem ?
> 
> Hm, for example,
> 
>      PageReserved(virt_to_page(address_of_obj)) ?
>      PageSlab(virt_to_page(address_of_obj)) ?
> 

Hi Kamezawa-san,

I think we can detect it without a new member. I think bootmem:1 member
is just for convenience. I think I can remove it. :)

Thanks. :)
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Christoph Lameter - Jan. 2, 2013, 2:24 p.m.
On Thu, 27 Dec 2012, Tang Chen wrote:

> On 12/26/2012 11:30 AM, Kamezawa Hiroyuki wrote:
> >> @@ -41,6 +42,7 @@ struct firmware_map_entry {
> >>    	const char		*type;	/* type of the memory range */
> >>    	struct list_head	list;	/* entry for the linked list */
> >>    	struct kobject		kobj;   /* kobject for each entry */
> >> +	unsigned int		bootmem:1; /* allocated from bootmem */
> >>    };
> >
> > Can't we detect from which the object is allocated from, slab or bootmem ?
> >
> > Hm, for example,
> >
> >      PageReserved(virt_to_page(address_of_obj)) ?
> >      PageSlab(virt_to_page(address_of_obj)) ?
> >
>
> Hi Kamezawa-san,
>
> I think we can detect it without a new member. I think bootmem:1 member
> is just for convenience. I think I can remove it. :)

Larger size slab allocations may fall back to the page allocator but then
the slabs do not track this allocation. That memory can be freed using the
page allocator.

If you see pageslab then you can always remove using the slab allocator.
Otherwise the page allocator should work (unless it was some
special case bootmem allocation).

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Patch

diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
index 90723e6..49be12a 100644
--- a/drivers/firmware/memmap.c
+++ b/drivers/firmware/memmap.c
@@ -21,6 +21,7 @@ 
 #include <linux/types.h>
 #include <linux/bootmem.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 
 /*
  * Data types ------------------------------------------------------------------
@@ -41,6 +42,7 @@  struct firmware_map_entry {
 	const char		*type;	/* type of the memory range */
 	struct list_head	list;	/* entry for the linked list */
 	struct kobject		kobj;   /* kobject for each entry */
+	unsigned int		bootmem:1; /* allocated from bootmem */
 };
 
 /*
@@ -79,7 +81,26 @@  static const struct sysfs_ops memmap_attr_ops = {
 	.show = memmap_attr_show,
 };
 
+
+static inline struct firmware_map_entry *
+to_memmap_entry(struct kobject *kobj)
+{
+	return container_of(kobj, struct firmware_map_entry, kobj);
+}
+
+static void release_firmware_map_entry(struct kobject *kobj)
+{
+	struct firmware_map_entry *entry = to_memmap_entry(kobj);
+
+	if (entry->bootmem)
+		/* There is no way to free memory allocated from bootmem */
+		return;
+
+	kfree(entry);
+}
+
 static struct kobj_type memmap_ktype = {
+	.release	= release_firmware_map_entry,
 	.sysfs_ops	= &memmap_attr_ops,
 	.default_attrs	= def_attrs,
 };
@@ -94,6 +115,7 @@  static struct kobj_type memmap_ktype = {
  * in firmware initialisation code in one single thread of execution.
  */
 static LIST_HEAD(map_entries);
+static DEFINE_SPINLOCK(map_entries_lock);
 
 /**
  * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
@@ -118,11 +140,25 @@  static int firmware_map_add_entry(u64 start, u64 end,
 	INIT_LIST_HEAD(&entry->list);
 	kobject_init(&entry->kobj, &memmap_ktype);
 
+	spin_lock(&map_entries_lock);
 	list_add_tail(&entry->list, &map_entries);
+	spin_unlock(&map_entries_lock);
 
 	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)
+{
+	spin_lock(&map_entries_lock);
+	list_del(&entry->list);
+	spin_unlock(&map_entries_lock);
+}
+
 /*
  * Add memmap entry on sysfs
  */
@@ -144,6 +180,35 @@  static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 	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
+ */
+
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry(u64 start, u64 end, const char *type)
+{
+	struct firmware_map_entry *entry;
+
+	spin_lock(&map_entries_lock);
+	list_for_each_entry(entry, &map_entries, list)
+		if ((entry->start == start) && (entry->end == end) &&
+		    (!strcmp(entry->type, type))) {
+			spin_unlock(&map_entries_lock);
+			return entry;
+		}
+
+	spin_unlock(&map_entries_lock);
+	return NULL;
+}
+
 /**
  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
  * memory hotplug.
@@ -193,9 +258,36 @@  int __init firmware_map_add_early(u64 start, u64 end, const char *type)
 	if (WARN_ON(!entry))
 		return -ENOMEM;
 
+	entry->bootmem = 1;
 	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.
+ * @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 = firmware_map_find_entry(start, end - 1, type);
+	if (!entry)
+		return -EINVAL;
+
+	firmware_map_remove_entry(entry);
+
+	/* remove the memmap entry */
+	remove_sysfs_fw_map_entry(entry);
+
+	return 0;
+}
+
 /*
  * Sysfs functions -------------------------------------------------------------
  */
@@ -217,8 +309,10 @@  static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
 	return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 }
 
-#define to_memmap_attr(_attr) container_of(_attr, struct memmap_attribute, attr)
-#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
+static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
+{
+	return container_of(attr, struct memmap_attribute, attr);
+}
 
 static ssize_t memmap_attr_show(struct kobject *kobj,
 				struct attribute *attr, char *buf)
diff --git a/include/linux/firmware-map.h b/include/linux/firmware-map.h
index 43fe52f..71d4fa7 100644
--- a/include/linux/firmware-map.h
+++ b/include/linux/firmware-map.h
@@ -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_hotplug(u64 start, u64 end, const char *type)
 	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 */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dbb04d8..1f5b5bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1442,7 +1442,7 @@  static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
 	return ret;
 }
 
-int remove_memory(u64 start, u64 size)
+int __ref remove_memory(u64 start, u64 size)
 {
 	unsigned long start_pfn, end_pfn;
 	int ret = 0;
@@ -1484,6 +1484,9 @@  repeat:
 		return ret;
 	}
 
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size, "System RAM");
+
 	unlock_memory_hotplug();
 
 	return 0;