From e4b294c2d8f73af4cd41ff30638ad0e4769dc56a Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 11 Feb 2015 15:24:46 -0800 Subject: [PATCH] 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 Acked-by: Jerome Marchand Acked-by: Christoph Lameter Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 9 ++++----- include/linux/mm_types.h | 8 ++++++++ 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 65db4aee738a..8dd4fde9d2e5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -627,29 +627,28 @@ int split_free_page(struct page *page); * prototype for that function and accessor functions. * 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, 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) { - return (compound_page_dtor *)page[1].lru.next; + return page[1].compound_dtor; } static inline int compound_order(struct page *page) { if (!PageHead(page)) 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) { - page[1].lru.prev = (void *)order; + page[1].compound_order = order; } #ifdef CONFIG_MMU diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 07c8bd3f7b48..20ff2105b564 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -28,6 +28,8 @@ struct mem_cgroup; IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK)) #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 * 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 * 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 pgtable_t pmd_huge_pte; /* protected by page->ptl */ #endif -- 2.39.2