From 539edb5846c740d78a8b6c2e43a99ca4323df68f Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 14 Nov 2013 14:31:52 -0800 Subject: [PATCH] mm: properly separate the bloated ptl from the regular case Use kernel/bounds.c to convert build-time spinlock_t size check into a preprocessor symbol and apply that to properly separate the page::ptl situation. Signed-off-by: Peter Zijlstra Signed-off-by: Kirill A. Shutemov Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 24 +++++++++++++----------- include/linux/mm_types.h | 9 +++++---- kernel/bounds.c | 2 ++ mm/memory.c | 11 +++++------ 4 files changed, 25 insertions(+), 21 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index d0339741b6ce..1cedd000cf29 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1317,27 +1317,29 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a #endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */ #if USE_SPLIT_PTE_PTLOCKS -bool __ptlock_alloc(struct page *page); -void __ptlock_free(struct page *page); +#if BLOATED_SPINLOCKS +extern bool ptlock_alloc(struct page *page); +extern void ptlock_free(struct page *page); + +static inline spinlock_t *ptlock_ptr(struct page *page) +{ + return page->ptl; +} +#else /* BLOATED_SPINLOCKS */ static inline bool ptlock_alloc(struct page *page) { - if (sizeof(spinlock_t) > sizeof(page->ptl)) - return __ptlock_alloc(page); return true; } + static inline void ptlock_free(struct page *page) { - if (sizeof(spinlock_t) > sizeof(page->ptl)) - __ptlock_free(page); } static inline spinlock_t *ptlock_ptr(struct page *page) { - if (sizeof(spinlock_t) > sizeof(page->ptl)) - return (spinlock_t *) page->ptl; - else - return (spinlock_t *) &page->ptl; + return &page->ptl; } +#endif /* BLOATED_SPINLOCKS */ static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd) { @@ -1354,7 +1356,7 @@ static inline bool ptlock_init(struct page *page) * slab code uses page->slab_cache and page->first_page (for tail * pages), which share storage with page->ptl. */ - VM_BUG_ON(page->ptl); + VM_BUG_ON(*(unsigned long *)&page->ptl); if (!ptlock_alloc(page)) return false; spin_lock_init(ptlock_ptr(page)); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 423da79877e6..10f5a7272b80 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -147,10 +147,11 @@ struct page { * system if PG_buddy is set. */ #if USE_SPLIT_PTE_PTLOCKS - unsigned long ptl; /* It's spinlock_t if it fits to long, - * otherwise it's pointer to dynamicaly - * allocated spinlock_t. - */ +#if BLOATED_SPINLOCKS + spinlock_t *ptl; +#else + spinlock_t ptl; +#endif #endif struct kmem_cache *slab_cache; /* SL[AU]B: Pointer to slab */ struct page *first_page; /* Compound tail pages */ diff --git a/kernel/bounds.c b/kernel/bounds.c index e8ca97b5c386..578782ef6ae1 100644 --- a/kernel/bounds.c +++ b/kernel/bounds.c @@ -11,6 +11,7 @@ #include #include #include +#include void foo(void) { @@ -21,5 +22,6 @@ void foo(void) #ifdef CONFIG_SMP DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS)); #endif + DEFINE(BLOATED_SPINLOCKS, sizeof(spinlock_t) > sizeof(int)); /* End of constants */ } diff --git a/mm/memory.c b/mm/memory.c index 24ffae2a530e..5d9025f3b3e1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4271,21 +4271,20 @@ void copy_user_huge_page(struct page *dst, struct page *src, } #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ -#if USE_SPLIT_PTE_PTLOCKS -bool __ptlock_alloc(struct page *page) +#if USE_SPLIT_PTE_PTLOCKS && BLOATED_SPINLOCKS +bool ptlock_alloc(struct page *page) { spinlock_t *ptl; ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL); if (!ptl) return false; - page->ptl = (unsigned long)ptl; + page->ptl = ptl; return true; } -void __ptlock_free(struct page *page) +void ptlock_free(struct page *page) { - if (sizeof(spinlock_t) > sizeof(page->ptl)) - kfree((spinlock_t *)page->ptl); + kfree(page->ptl); } #endif -- 2.20.1