Re: [PATCH v2 2/6] mm/balloon_compaction: keep ballooned pages away from normal migration path

2014-09-02 Thread Rafael Aquini 
On Sat, Aug 30, 2014 at 08:41:13PM +0400, Konstantin Khlebnikov wrote:
> From: Konstantin Khlebnikov 
> 
> Proper testing shows yet another problem in balloon migration: it works only
> once for each page. balloon_page_movable() check page flags and page_count.
> In __unmap_and_move page is locked, reference counter is elevated, so
> balloon_page_movable() _always_ fails here. As result in __unmap_and_move()
> migration goes to the normal migration path.
> 
> Balloon ->migratepage() is so special, it returns MIGRATEPAGE_BALLOON_SUCCESS
> instead of MIGRATEPAGE_SUCCESS. After that in move_to_new_page() successfully
> migrated page got NULL into its mapping pointer and loses connectivity with
> balloon and ability for further migration.
> 
> It's safe to use __is_movable_balloon_page here: page is isolated and pinned.
> 
> Signed-off-by: Konstantin Khlebnikov 
> Cc: stable  # v3.8
> ---
>  include/linux/balloon_compaction.h |5 +
>  mm/migrate.c   |2 +-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/balloon_compaction.h 
> b/include/linux/balloon_compaction.h
> index 53d482e..284fc1d 100644
> --- a/include/linux/balloon_compaction.h
> +++ b/include/linux/balloon_compaction.h
> @@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page)
>   list_del(>lru);
>  }
>  
> +static inline bool __is_movable_balloon_page(struct page *page)
> +{
> + return false;
> +}
> +
>  static inline bool balloon_page_movable(struct page *page)
>  {
>   return false;
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 905b1aa..57c94f9 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct 
> page *newpage,
>   }
>   }
>  
> - if (unlikely(balloon_page_movable(page))) {
> + if (unlikely(__is_movable_balloon_page(page))) {
>   /*
>* A ballooned page does not need any special attention from
>* physical to virtual reverse mapping procedures.
> 
Acked-by: Rafael Aquini 

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Re: [PATCH v2 2/6] mm/balloon_compaction: keep ballooned pages away from normal migration path

2014-09-02 Thread Rafael Aquini 
On Sat, Aug 30, 2014 at 08:41:13PM +0400, Konstantin Khlebnikov wrote:
 From: Konstantin Khlebnikov k.khlebni...@samsung.com
 
 Proper testing shows yet another problem in balloon migration: it works only
 once for each page. balloon_page_movable() check page flags and page_count.
 In __unmap_and_move page is locked, reference counter is elevated, so
 balloon_page_movable() _always_ fails here. As result in __unmap_and_move()
 migration goes to the normal migration path.
 
 Balloon -migratepage() is so special, it returns MIGRATEPAGE_BALLOON_SUCCESS
 instead of MIGRATEPAGE_SUCCESS. After that in move_to_new_page() successfully
 migrated page got NULL into its mapping pointer and loses connectivity with
 balloon and ability for further migration.
 
 It's safe to use __is_movable_balloon_page here: page is isolated and pinned.
 
 Signed-off-by: Konstantin Khlebnikov k.khlebni...@samsung.com
 Cc: stable sta...@vger.kernel.org # v3.8
 ---
  include/linux/balloon_compaction.h |5 +
  mm/migrate.c   |2 +-
  2 files changed, 6 insertions(+), 1 deletion(-)
 
 diff --git a/include/linux/balloon_compaction.h 
 b/include/linux/balloon_compaction.h
 index 53d482e..284fc1d 100644
 --- a/include/linux/balloon_compaction.h
 +++ b/include/linux/balloon_compaction.h
 @@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page)
   list_del(page-lru);
  }
  
 +static inline bool __is_movable_balloon_page(struct page *page)
 +{
 + return false;
 +}
 +
  static inline bool balloon_page_movable(struct page *page)
  {
   return false;
 diff --git a/mm/migrate.c b/mm/migrate.c
 index 905b1aa..57c94f9 100644
 --- a/mm/migrate.c
 +++ b/mm/migrate.c
 @@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct 
 page *newpage,
   }
   }
  
 - if (unlikely(balloon_page_movable(page))) {
 + if (unlikely(__is_movable_balloon_page(page))) {
   /*
* A ballooned page does not need any special attention from
* physical to virtual reverse mapping procedures.
 
Acked-by: Rafael Aquini aqu...@redhat.com

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[PATCH v2 2/6] mm/balloon_compaction: keep ballooned pages away from normal migration path

2014-08-30 Thread Konstantin Khlebnikov 
From: Konstantin Khlebnikov 

Proper testing shows yet another problem in balloon migration: it works only
once for each page. balloon_page_movable() check page flags and page_count.
In __unmap_and_move page is locked, reference counter is elevated, so
balloon_page_movable() _always_ fails here. As result in __unmap_and_move()
migration goes to the normal migration path.

Balloon ->migratepage() is so special, it returns MIGRATEPAGE_BALLOON_SUCCESS
instead of MIGRATEPAGE_SUCCESS. After that in move_to_new_page() successfully
migrated page got NULL into its mapping pointer and loses connectivity with
balloon and ability for further migration.

It's safe to use __is_movable_balloon_page here: page is isolated and pinned.

Signed-off-by: Konstantin Khlebnikov 
Cc: stable  # v3.8
---
 include/linux/balloon_compaction.h |5 +
 mm/migrate.c   |2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/balloon_compaction.h 
b/include/linux/balloon_compaction.h
index 53d482e..284fc1d 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page)
list_del(>lru);
 }
 
+static inline bool __is_movable_balloon_page(struct page *page)
+{
+   return false;
+}
+
 static inline bool balloon_page_movable(struct page *page)
 {
return false;
diff --git a/mm/migrate.c b/mm/migrate.c
index 905b1aa..57c94f9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page 
*newpage,
}
}
 
-   if (unlikely(balloon_page_movable(page))) {
+   if (unlikely(__is_movable_balloon_page(page))) {
/*
 * A ballooned page does not need any special attention from
 * physical to virtual reverse mapping procedures.

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[PATCH v2 2/6] mm/balloon_compaction: keep ballooned pages away from normal migration path

2014-08-30 Thread Konstantin Khlebnikov 
From: Konstantin Khlebnikov k.khlebni...@samsung.com

Proper testing shows yet another problem in balloon migration: it works only
once for each page. balloon_page_movable() check page flags and page_count.
In __unmap_and_move page is locked, reference counter is elevated, so
balloon_page_movable() _always_ fails here. As result in __unmap_and_move()
migration goes to the normal migration path.

Balloon -migratepage() is so special, it returns MIGRATEPAGE_BALLOON_SUCCESS
instead of MIGRATEPAGE_SUCCESS. After that in move_to_new_page() successfully
migrated page got NULL into its mapping pointer and loses connectivity with
balloon and ability for further migration.

It's safe to use __is_movable_balloon_page here: page is isolated and pinned.

Signed-off-by: Konstantin Khlebnikov k.khlebni...@samsung.com
Cc: stable sta...@vger.kernel.org # v3.8
---
 include/linux/balloon_compaction.h |5 +
 mm/migrate.c   |2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/balloon_compaction.h 
b/include/linux/balloon_compaction.h
index 53d482e..284fc1d 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page)
list_del(page-lru);
 }
 
+static inline bool __is_movable_balloon_page(struct page *page)
+{
+   return false;
+}
+
 static inline bool balloon_page_movable(struct page *page)
 {
return false;
diff --git a/mm/migrate.c b/mm/migrate.c
index 905b1aa..57c94f9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page 
*newpage,
}
}
 
-   if (unlikely(balloon_page_movable(page))) {
+   if (unlikely(__is_movable_balloon_page(page))) {
/*
 * A ballooned page does not need any special attention from
 * physical to virtual reverse mapping procedures.

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