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 <[email protected]>
---
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();
/*
On Thu, Aug 8, 2013 at 12:47 PM, Toshi Kani <[email protected]> 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 <[email protected]>
> ---
> 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 <[email protected]>
On Thu, 2013-08-08 at 15:53 -0400, KOSAKI Motohiro wrote:
> On Thu, Aug 8, 2013 at 12:47 PM, Toshi Kani <[email protected]> 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 <[email protected]>
> > ---
> > 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 <[email protected]>
Thanks!
-Toshi
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<[email protected]>
> ---
> 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 <[email protected]>
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();
>
> /*
>
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<[email protected]>
> > ---
> > 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 <[email protected]>
Thanks!
-Toshi