[PATCH R3 1/7] mm: Add add_registered_memory() to memory hotplug API

[PATCH R3 1/7] mm: Add add_registered_memory() to memory hotplug API

[Daniel Kiper]

add_registered_memory() adds memory ealier registered
as memory resource. It is required by memory hotplug
for Xen guests, however it could be used also by other
modules.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
---
 include/linux/memory_hotplug.h |    1 +
 mm/memory_hotplug.c            |   50 ++++++++++++++++++++++++++++++---------
 2 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 8122018..fe63912 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -223,6 +223,7 @@ static inline int is_mem_section_removable(unsigned long pfn,
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 extern int mem_online_node(int nid);
+extern int add_registered_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
 extern int arch_add_memory(int nid, u64 start, u64 size);
 extern int remove_memory(u64 start, u64 size);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 321fc74..7947bdf 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -532,20 +532,12 @@ out:
 }
 
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-int __ref add_memory(int nid, u64 start, u64 size)
+static int __ref __add_memory(int nid, u64 start, u64 size)
 {
 	pg_data_t *pgdat = NULL;
 	int new_pgdat = 0;
-	struct resource *res;
 	int ret;
 
-	lock_memory_hotplug();
-
-	res = register_memory_resource(start, size);
-	ret = -EEXIST;
-	if (!res)
-		goto out;
-
 	if (!node_online(nid)) {
 		pgdat = hotadd_new_pgdat(nid, start);
 		ret = -ENOMEM;
@@ -579,14 +571,48 @@ int __ref add_memory(int nid, u64 start, u64 size)
 	goto out;
 
 error:
-	/* rollback pgdat allocation and others */
+	/* rollback pgdat allocation */
 	if (new_pgdat)
 		rollback_node_hotadd(nid, pgdat);
-	if (res)
-		release_memory_resource(res);
+
+out:
+	return ret;
+}
+
+int add_registered_memory(int nid, u64 start, u64 size)
+{
+	int ret;
+
+	lock_memory_hotplug();
+	ret = __add_memory(nid, start, size);
+	unlock_memory_hotplug();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(add_registered_memory);
+
+int add_memory(int nid, u64 start, u64 size)
+{
+	int ret = -EEXIST;
+	struct resource *res;
+
+	lock_memory_hotplug();
+
+	res = register_memory_resource(start, size);
+
+	if (!res)
+		goto out;
+
+	ret = __add_memory(nid, start, size);
+
+	if (!ret)
+		goto out;
+
+	release_memory_resource(res);
 
 out:
 	unlock_memory_hotplug();
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(add_memory);
-- 
1.5.6.5

Re: [PATCH R3 1/7] mm: Add add_registered_memory() to memory hotplug API

[Konrad Rzeszutek Wilk]

On Thu, Feb 03, 2011 at 05:25:14PM +0100, Daniel Kiper wrote:
> add_registered_memory() adds memory ealier registered
> as memory resource. It is required by memory hotplug
> for Xen guests, however it could be used also by other
> modules.
> 
> Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
> ---
>  include/linux/memory_hotplug.h |    1 +
>  mm/memory_hotplug.c            |   50 ++++++++++++++++++++++++++++++---------
>  2 files changed, 39 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 8122018..fe63912 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -223,6 +223,7 @@ static inline int is_mem_section_removable(unsigned long pfn,
>  #endif /* CONFIG_MEMORY_HOTREMOVE */
>  
>  extern int mem_online_node(int nid);
> +extern int add_registered_memory(int nid, u64 start, u64 size);
>  extern int add_memory(int nid, u64 start, u64 size);
>  extern int arch_add_memory(int nid, u64 start, u64 size);
>  extern int remove_memory(u64 start, u64 size);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 321fc74..7947bdf 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -532,20 +532,12 @@ out:
>  }
>  
>  /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
> -int __ref add_memory(int nid, u64 start, u64 size)
> +static int __ref __add_memory(int nid, u64 start, u64 size)
>  {
>  	pg_data_t *pgdat = NULL;
>  	int new_pgdat = 0;
> -	struct resource *res;
>  	int ret;
>  
> -	lock_memory_hotplug();
> -
> -	res = register_memory_resource(start, size);
> -	ret = -EEXIST;
> -	if (!res)
> -		goto out;
> -
>  	if (!node_online(nid)) {
>  		pgdat = hotadd_new_pgdat(nid, start);
>  		ret = -ENOMEM;
> @@ -579,14 +571,48 @@ int __ref add_memory(int nid, u64 start, u64 size)
>  	goto out;
>  
>  error:
> -	/* rollback pgdat allocation and others */
> +	/* rollback pgdat allocation */
>  	if (new_pgdat)
>  		rollback_node_hotadd(nid, pgdat);
> -	if (res)
> -		release_memory_resource(res);
> +
> +out:
> +	return ret;
> +}
> +
> +int add_registered_memory(int nid, u64 start, u64 size)
> +{
> +	int ret;
> +
> +	lock_memory_hotplug();
> +	ret = __add_memory(nid, start, size);
> +	unlock_memory_hotplug();

Isn't this a duplicate call to the mutex?
The __add_memory does an unlock_memory_hotplug when it finishes
and then you do another unlock_memory_hotplug here too.


> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(add_registered_memory);
> +
> +int add_memory(int nid, u64 start, u64 size)
> +{
> +	int ret = -EEXIST;
> +	struct resource *res;
> +
> +	lock_memory_hotplug();
> +
> +	res = register_memory_resource(start, size);
> +
> +	if (!res)
> +		goto out;
> +
> +	ret = __add_memory(nid, start, size);

Ditto here. When __add_memory finishes the unlock_memory_hotplug
has been called, but you end up doing it in the out: label
too?

> +
> +	if (!ret)
> +		goto out;
> +
> +	release_memory_resource(res);
>  
>  out:
>  	unlock_memory_hotplug();
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(add_memory);
> -- 
> 1.5.6.5

Re: [PATCH R3 1/7] mm: Add add_registered_memory() to memory hotplug API

[Daniel Kiper]

On Tue, Feb 08, 2011 at 06:25:38PM -0500, Konrad Rzeszutek Wilk wrote:
> On Thu, Feb 03, 2011 at 05:25:14PM +0100, Daniel Kiper wrote:
> > add_registered_memory() adds memory ealier registered
> > as memory resource. It is required by memory hotplug
> > for Xen guests, however it could be used also by other
> > modules.
> > 
> > Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
> > ---
> >  include/linux/memory_hotplug.h |    1 +
> >  mm/memory_hotplug.c            |   50 ++++++++++++++++++++++++++++++---------
> >  2 files changed, 39 insertions(+), 12 deletions(-)
> > 
> > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> > index 8122018..fe63912 100644
> > --- a/include/linux/memory_hotplug.h
> > +++ b/include/linux/memory_hotplug.h
> > @@ -223,6 +223,7 @@ static inline int is_mem_section_removable(unsigned long pfn,
> >  #endif /* CONFIG_MEMORY_HOTREMOVE */
> >  
> >  extern int mem_online_node(int nid);
> > +extern int add_registered_memory(int nid, u64 start, u64 size);
> >  extern int add_memory(int nid, u64 start, u64 size);
> >  extern int arch_add_memory(int nid, u64 start, u64 size);
> >  extern int remove_memory(u64 start, u64 size);
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index 321fc74..7947bdf 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -532,20 +532,12 @@ out:
> >  }
> >  
> >  /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
> > -int __ref add_memory(int nid, u64 start, u64 size)
> > +static int __ref __add_memory(int nid, u64 start, u64 size)
> >  {
> >  	pg_data_t *pgdat = NULL;
> >  	int new_pgdat = 0;
> > -	struct resource *res;
> >  	int ret;
> >  
> > -	lock_memory_hotplug();
> > -
> > -	res = register_memory_resource(start, size);
> > -	ret = -EEXIST;
> > -	if (!res)
> > -		goto out;
> > -
> >  	if (!node_online(nid)) {
> >  		pgdat = hotadd_new_pgdat(nid, start);
> >  		ret = -ENOMEM;
> > @@ -579,14 +571,48 @@ int __ref add_memory(int nid, u64 start, u64 size)
> >  	goto out;
> >  
> >  error:
> > -	/* rollback pgdat allocation and others */
> > +	/* rollback pgdat allocation */
> >  	if (new_pgdat)
> >  		rollback_node_hotadd(nid, pgdat);
> > -	if (res)
> > -		release_memory_resource(res);
> > +
> > +out:
> > +	return ret;
> > +}
> > +
> > +int add_registered_memory(int nid, u64 start, u64 size)
> > +{
> > +	int ret;
> > +
> > +	lock_memory_hotplug();
> > +	ret = __add_memory(nid, start, size);
> > +	unlock_memory_hotplug();
> 
> Isn't this a duplicate call to the mutex?
> The __add_memory does an unlock_memory_hotplug when it finishes
> and then you do another unlock_memory_hotplug here too.

No. Calls to lock_memory_hotplug()/unlock_memory_hotplug() were
moved from original add_memory() to add_registered_memory()
and new add_memory().

Daniel