[PATCH] mm/hotplug: Verify hotplug memory range

[PATCH] mm/hotplug: Verify hotplug memory range

[Toshi Kani]

add_memory() and remove_memory() can only handle a memory range aligned
with section.  There are problems when an unaligned range is added and
then deleted as follows:

 - add_memory() with an unaligned range succeeds, but __add_pages()
   called from add_memory() adds a whole section of pages even though
   a given memory range is less than the section size.
 - remove_memory() to the added unaligned range hits BUG_ON() in
   __remove_pages().

This patch changes add_memory() and remove_memory() to check if a given
memory range is aligned with section at the beginning.  As the result,
add_memory() fails with -EINVAL when a given range is unaligned, and
does not add such memory range.  This prevents remove_memory() to be
called with an unaligned range as well.  Note that remove_memory() has
to use BUG_ON() since this function cannot fail.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
 mm/memory_hotplug.c |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index ca1dd3a..ac182de 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1069,6 +1069,22 @@ out:
 	return ret;
 }
 
+static int check_hotplug_memory_range(u64 start, u64 size)
+{
+	u64 start_pfn = start >> PAGE_SHIFT;
+	u64 nr_pages = size >> PAGE_SHIFT;
+
+	/* Memory range must be aligned with section */
+	if ((start_pfn & ~PAGE_SECTION_MASK) ||
+	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
+		pr_err("Unsupported hotplug range: start 0x%llx, size 0x%llx\n",
+				start, size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
 int __ref add_memory(int nid, u64 start, u64 size)
 {
@@ -1078,6 +1094,10 @@ int __ref add_memory(int nid, u64 start, u64 size)
 	struct resource *res;
 	int ret;
 
+	ret = check_hotplug_memory_range(start, size);
+	if (ret)
+		return ret;
+
 	lock_memory_hotplug();
 
 	res = register_memory_resource(start, size);
@@ -1786,6 +1806,8 @@ void __ref remove_memory(int nid, u64 start, u64 size)
 {
 	int ret;
 
+	BUG_ON(check_hotplug_memory_range(start, size));
+
 	lock_memory_hotplug();
 
 	/*

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/hotplug: Verify hotplug memory range

[KOSAKI Motohiro]

On Thu, Aug 8, 2013 at 12:47 PM, Toshi Kani <toshi.kani@hp.com> wrote:
> add_memory() and remove_memory() can only handle a memory range aligned
> with section.  There are problems when an unaligned range is added and
> then deleted as follows:
>
>  - add_memory() with an unaligned range succeeds, but __add_pages()
>    called from add_memory() adds a whole section of pages even though
>    a given memory range is less than the section size.
>  - remove_memory() to the added unaligned range hits BUG_ON() in
>    __remove_pages().
>
> This patch changes add_memory() and remove_memory() to check if a given
> memory range is aligned with section at the beginning.  As the result,
> add_memory() fails with -EINVAL when a given range is unaligned, and
> does not add such memory range.  This prevents remove_memory() to be
> called with an unaligned range as well.  Note that remove_memory() has
> to use BUG_ON() since this function cannot fail.
>
> Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> ---
>  mm/memory_hotplug.c |   22 ++++++++++++++++++++++

memory_hotplug.c is maintained by me and kamezawa-san. Please cc us
if you have a subsequent patch.

Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/hotplug: Verify hotplug memory range

[Toshi Kani]

On Thu, 2013-08-08 at 15:53 -0400, KOSAKI Motohiro wrote:
> On Thu, Aug 8, 2013 at 12:47 PM, Toshi Kani <toshi.kani@hp.com> wrote:
> > add_memory() and remove_memory() can only handle a memory range aligned
> > with section.  There are problems when an unaligned range is added and
> > then deleted as follows:
> >
> >  - add_memory() with an unaligned range succeeds, but __add_pages()
> >    called from add_memory() adds a whole section of pages even though
> >    a given memory range is less than the section size.
> >  - remove_memory() to the added unaligned range hits BUG_ON() in
> >    __remove_pages().
> >
> > This patch changes add_memory() and remove_memory() to check if a given
> > memory range is aligned with section at the beginning.  As the result,
> > add_memory() fails with -EINVAL when a given range is unaligned, and
> > does not add such memory range.  This prevents remove_memory() to be
> > called with an unaligned range as well.  Note that remove_memory() has
> > to use BUG_ON() since this function cannot fail.
> >
> > Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> > ---
> >  mm/memory_hotplug.c |   22 ++++++++++++++++++++++
> 
> memory_hotplug.c is maintained by me and kamezawa-san. Please cc us
> if you have a subsequent patch.

Oh, I see.  Sorry about that.  Yes, I will copy you two from the next
time. 

> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Thanks!
-Toshi

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/hotplug: Verify hotplug memory range

[Tang Chen]

On 08/09/2013 12:47 AM, Toshi Kani wrote:
> add_memory() and remove_memory() can only handle a memory range aligned
> with section.  There are problems when an unaligned range is added and
> then deleted as follows:
>
>   - add_memory() with an unaligned range succeeds, but __add_pages()
>     called from add_memory() adds a whole section of pages even though
>     a given memory range is less than the section size.
>   - remove_memory() to the added unaligned range hits BUG_ON() in
>     __remove_pages().
>
> This patch changes add_memory() and remove_memory() to check if a given
> memory range is aligned with section at the beginning.  As the result,
> add_memory() fails with -EINVAL when a given range is unaligned, and
> does not add such memory range.  This prevents remove_memory() to be
> called with an unaligned range as well.  Note that remove_memory() has
> to use BUG_ON() since this function cannot fail.
>
> Signed-off-by: Toshi Kani<toshi.kani@hp.com>
> ---
>   mm/memory_hotplug.c |   22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index ca1dd3a..ac182de 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1069,6 +1069,22 @@ out:
>   	return ret;
>   }
>
> +static int check_hotplug_memory_range(u64 start, u64 size)
> +{
> +	u64 start_pfn = start>>  PAGE_SHIFT;
> +	u64 nr_pages = size>>  PAGE_SHIFT;
> +
> +	/* Memory range must be aligned with section */
> +	if ((start_pfn&  ~PAGE_SECTION_MASK) ||
> +	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
> +		pr_err("Unsupported hotplug range: start 0x%llx, size 0x%llx\n",
> +				start, size);

I think the message here should tell users that only support range aligned
to section. Others seems OK to me.

Reviewed-by: Tang Chen <tangchen@cn.fujitsu.com>

Thanks.

> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>   /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
>   int __ref add_memory(int nid, u64 start, u64 size)
>   {
> @@ -1078,6 +1094,10 @@ int __ref add_memory(int nid, u64 start, u64 size)
>   	struct resource *res;
>   	int ret;
>
> +	ret = check_hotplug_memory_range(start, size);
> +	if (ret)
> +		return ret;
> +
>   	lock_memory_hotplug();
>
>   	res = register_memory_resource(start, size);
> @@ -1786,6 +1806,8 @@ void __ref remove_memory(int nid, u64 start, u64 size)
>   {
>   	int ret;
>
> +	BUG_ON(check_hotplug_memory_range(start, size));
> +
>   	lock_memory_hotplug();
>
>   	/*
>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/hotplug: Verify hotplug memory range

[Toshi Kani]

On Fri, 2013-08-09 at 13:52 +0800, Tang Chen wrote:
> On 08/09/2013 12:47 AM, Toshi Kani wrote:
> > add_memory() and remove_memory() can only handle a memory range aligned
> > with section.  There are problems when an unaligned range is added and
> > then deleted as follows:
> >
> >   - add_memory() with an unaligned range succeeds, but __add_pages()
> >     called from add_memory() adds a whole section of pages even though
> >     a given memory range is less than the section size.
> >   - remove_memory() to the added unaligned range hits BUG_ON() in
> >     __remove_pages().
> >
> > This patch changes add_memory() and remove_memory() to check if a given
> > memory range is aligned with section at the beginning.  As the result,
> > add_memory() fails with -EINVAL when a given range is unaligned, and
> > does not add such memory range.  This prevents remove_memory() to be
> > called with an unaligned range as well.  Note that remove_memory() has
> > to use BUG_ON() since this function cannot fail.
> >
> > Signed-off-by: Toshi Kani<toshi.kani@hp.com>
> > ---
> >   mm/memory_hotplug.c |   22 ++++++++++++++++++++++
> >   1 file changed, 22 insertions(+)
> >
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index ca1dd3a..ac182de 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1069,6 +1069,22 @@ out:
> >   	return ret;
> >   }
> >
> > +static int check_hotplug_memory_range(u64 start, u64 size)
> > +{
> > +	u64 start_pfn = start>>  PAGE_SHIFT;
> > +	u64 nr_pages = size>>  PAGE_SHIFT;
> > +
> > +	/* Memory range must be aligned with section */
> > +	if ((start_pfn&  ~PAGE_SECTION_MASK) ||
> > +	    (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) {
> > +		pr_err("Unsupported hotplug range: start 0x%llx, size 0x%llx\n",
> > +				start, size);
> 
> I think the message here should tell users that only support range aligned
> to section. Others seems OK to me.

OK, I will change the message to something like this:

  pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
                                start, size);

> Reviewed-by: Tang Chen <tangchen@cn.fujitsu.com>

Thanks!
-Toshi




--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>