From b7ccc7f8c643de0b71cd2da3245d0c27038a8dd7 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Thu, 7 Jun 2018 17:08:46 -0700 Subject: [PATCH] mm: move lru union within struct page MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since the LRU is two words, this does not affect the double-word alignment of SLUB's freelist. Link: http://lkml.kernel.org/r/20180518194519.3820-10-willy@infradead.org Signed-off-by: Matthew Wilcox Acked-by: Vlastimil Babka Acked-by: Kirill A. Shutemov Cc: Christoph Lameter Cc: Dave Hansen Cc: Jérôme Glisse Cc: Lai Jiangshan Cc: Martin Schwidefsky Cc: Pekka Enberg Cc: Randy Dunlap Cc: Andrey Ryabinin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm_types.h | 102 +++++++++++++++++++-------------------- mm/slub.c | 8 +-- 2 files changed, 55 insertions(+), 55 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 158f9693f865..5b97bd445ada 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -72,6 +72,57 @@ struct hmm; struct page { unsigned long flags; /* Atomic flags, some possibly * updated asynchronously */ + /* + * WARNING: bit 0 of the first word encode PageTail(). That means + * the rest users of the storage space MUST NOT use the bit to + * avoid collision and false-positive PageTail(). + */ + union { + struct list_head lru; /* Pageout list, eg. active_list + * protected by zone_lru_lock ! + * Can be used as a generic list + * by the page owner. + */ + struct dev_pagemap *pgmap; /* ZONE_DEVICE pages are never on an + * lru or handled by a slab + * allocator, this points to the + * hosting device page map. + */ + struct { /* slub per cpu partial pages */ + struct page *next; /* Next partial slab */ +#ifdef CONFIG_64BIT + int pages; /* Nr of partial slabs left */ + int pobjects; /* Approximate # of objects */ +#else + short int pages; + short int pobjects; +#endif + }; + + struct rcu_head rcu_head; /* Used by SLAB + * when destroying via RCU + */ + /* Tail pages of compound page */ + struct { + unsigned long compound_head; /* If bit zero is set */ + + /* First tail page only */ + unsigned char compound_dtor; + unsigned char compound_order; + /* two/six bytes available here */ + }; + +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS + struct { + unsigned long __pad; /* do not overlay pmd_huge_pte + * with compound_head to avoid + * possible bit 0 collision. + */ + pgtable_t pmd_huge_pte; /* protected by page->ptl */ + }; +#endif + }; + /* Three words (12/24 bytes) are available in this union. */ union { struct { /* Page cache and anonymous pages */ @@ -135,57 +186,6 @@ struct page { /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */ atomic_t _refcount; - /* - * WARNING: bit 0 of the first word encode PageTail(). That means - * the rest users of the storage space MUST NOT use the bit to - * avoid collision and false-positive PageTail(). - */ - union { - struct list_head lru; /* Pageout list, eg. active_list - * protected by zone_lru_lock ! - * Can be used as a generic list - * by the page owner. - */ - struct dev_pagemap *pgmap; /* ZONE_DEVICE pages are never on an - * lru or handled by a slab - * allocator, this points to the - * hosting device page map. - */ - struct { /* slub per cpu partial pages */ - struct page *next; /* Next partial slab */ -#ifdef CONFIG_64BIT - int pages; /* Nr of partial slabs left */ - int pobjects; /* Approximate # of objects */ -#else - short int pages; - short int pobjects; -#endif - }; - - struct rcu_head rcu_head; /* Used by SLAB - * when destroying via RCU - */ - /* Tail pages of compound page */ - struct { - unsigned long compound_head; /* If bit zero is set */ - - /* First tail page only */ - unsigned char compound_dtor; - unsigned char compound_order; - /* two/six bytes available here */ - }; - -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS - struct { - unsigned long __pad; /* do not overlay pmd_huge_pte - * with compound_head to avoid - * possible bit 0 collision. - */ - pgtable_t pmd_huge_pte; /* protected by page->ptl */ - }; -#endif - }; - #ifdef CONFIG_MEMCG struct mem_cgroup *mem_cgroup; #endif diff --git a/mm/slub.c b/mm/slub.c index f5db87839ab4..a96bf429af08 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -52,11 +52,11 @@ * and to synchronize major metadata changes to slab cache structures. * * The slab_lock is only used for debugging and on arches that do not - * have the ability to do a cmpxchg_double. It only protects the second - * double word in the page struct. Meaning + * have the ability to do a cmpxchg_double. It only protects: * A. page->freelist -> List of object free in a page - * B. page->counters -> Counters of objects - * C. page->frozen -> frozen state + * B. page->inuse -> Number of objects in use + * C. page->objects -> Number of objects in page + * D. page->frozen -> frozen state * * If a slab is frozen then it is exempt from list management. It is not * on any list. The processor that froze the slab is the one who can