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mm: add fields for compound destructor and order into struct page 

Currently, we use lru.next/lru.prev plus cast to access or set
destructor and order of compound page.

Let's replace it with explicit fields in struct page.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2015-02-11 15:24:46 -08:00 committed by Linus Torvalds
parent aa7ed01f93
commit e4b294c2d8
2 changed files with 12 additions and 5 deletions
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9
include/linux/mm.h
View File

@ -627,29 +627,28 @@ int split_free_page(struct page *page);
* prototype for that function and accessor functions. * prototype for that function and accessor functions.
* These are _only_ valid on the head of a PG_compound page. * These are _only_ valid on the head of a PG_compound page.
*/ */
typedef void compound_page_dtor(struct page *);
static inline void set_compound_page_dtor(struct page *page, static inline void set_compound_page_dtor(struct page *page,
compound_page_dtor *dtor) compound_page_dtor *dtor)
{ {
page[1].lru.next = (void *)dtor; page[1].compound_dtor = dtor;
} }
static inline compound_page_dtor *get_compound_page_dtor(struct page *page) static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
{ {
return (compound_page_dtor *)page[1].lru.next; return page[1].compound_dtor;
} }
static inline int compound_order(struct page *page) static inline int compound_order(struct page *page)
{ {
if (!PageHead(page)) if (!PageHead(page))
return 0; return 0;
return (unsigned long)page[1].lru.prev; return page[1].compound_order;
} }
static inline void set_compound_order(struct page *page, unsigned long order) static inline void set_compound_order(struct page *page, unsigned long order)
{ {
page[1].lru.prev = (void *)order; page[1].compound_order = order;
} }
#ifdef CONFIG_MMU #ifdef CONFIG_MMU

8
include/linux/mm_types.h
View File

@ -28,6 +28,8 @@ struct mem_cgroup;
IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK)) IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
#define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8) #define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
typedef void compound_page_dtor(struct page *);
/* /*
* Each physical page in the system has a struct page associated with * Each physical page in the system has a struct page associated with
* it to keep track of whatever it is we are using the page for at the * it to keep track of whatever it is we are using the page for at the
@ -142,6 +144,12 @@ struct page {
struct rcu_head rcu_head; /* Used by SLAB struct rcu_head rcu_head; /* Used by SLAB
* when destroying via RCU * when destroying via RCU
*/ */
/* First tail page of compound page */
struct {
compound_page_dtor *compound_dtor;
unsigned long compound_order;
};
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
pgtable_t pmd_huge_pte; /* protected by page->ptl */ pgtable_t pmd_huge_pte; /* protected by page->ptl */
#endif #endif