The thp page table pre-allocation code currently assumes that pgtable_t is of type "struct page *". This may not be true for all architectures, so this patch removes that assumption by replacing the functions prepare_pmd_huge_pte() and get_pmd_huge_pte() with two new functions that can be defined architecture-specific. It also removes two VM_BUG_ON checks for page_count() and page_mapcount() operating on a pgtable_t. Apart from the VM_BUG_ON removal, there will be no functional change introduced by this patch. Signed-off-by: Gerald Schaefer --- include/asm-generic/pgtable.h | 6 +++++ include/linux/huge_mm.h | 1 mm/huge_memory.c | 46 +++++------------------------------------- mm/pgtable-generic.c | 39 +++++++++++++++++++++++++++++++++++ 4 files changed, 51 insertions(+), 41 deletions(-) --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -443,6 +443,12 @@ static inline int pmd_write(pmd_t pmd) return 0; } #endif /* __HAVE_ARCH_PMD_WRITE */ +#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT +extern void pgtable_deposit(struct mm_struct *mm, pgtable_t pgtable); +#endif +#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW +extern pgtable_t pgtable_withdraw(struct mm_struct *mm); +#endif #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #ifndef pmd_read_atomic --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -11,7 +11,6 @@ extern int copy_huge_pmd(struct mm_struc extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, pmd_t orig_pmd); -extern pgtable_t get_pmd_huge_pte(struct mm_struct *mm); extern struct page *follow_trans_huge_pmd(struct mm_struct *mm, unsigned long addr, pmd_t *pmd, --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -611,19 +611,6 @@ out: } __setup("transparent_hugepage=", setup_transparent_hugepage); -static void prepare_pmd_huge_pte(pgtable_t pgtable, - struct mm_struct *mm) -{ - assert_spin_locked(&mm->page_table_lock); - - /* FIFO */ - if (!mm->pmd_huge_pte) - INIT_LIST_HEAD(&pgtable->lru); - else - list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); - mm->pmd_huge_pte = pgtable; -} - static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) { if (likely(vma->vm_flags & VM_WRITE)) @@ -665,7 +652,7 @@ static int __do_huge_pmd_anonymous_page( */ page_add_new_anon_rmap(page, vma, haddr); set_pmd_at(mm, haddr, pmd, entry); - prepare_pmd_huge_pte(pgtable, mm); + pgtable_deposit(mm, pgtable); add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); mm->nr_ptes++; spin_unlock(&mm->page_table_lock); @@ -791,7 +778,7 @@ int copy_huge_pmd(struct mm_struct *dst_ pmdp_set_wrprotect(src_mm, addr, src_pmd); pmd = pmd_mkold(pmd_wrprotect(pmd)); set_pmd_at(dst_mm, addr, dst_pmd, pmd); - prepare_pmd_huge_pte(pgtable, dst_mm); + pgtable_deposit(dst_mm, pgtable); dst_mm->nr_ptes++; ret = 0; @@ -802,25 +789,6 @@ out: return ret; } -/* no "address" argument so destroys page coloring of some arch */ -pgtable_t get_pmd_huge_pte(struct mm_struct *mm) -{ - pgtable_t pgtable; - - assert_spin_locked(&mm->page_table_lock); - - /* FIFO */ - pgtable = mm->pmd_huge_pte; - if (list_empty(&pgtable->lru)) - mm->pmd_huge_pte = NULL; - else { - mm->pmd_huge_pte = list_entry(pgtable->lru.next, - struct page, lru); - list_del(&pgtable->lru); - } - return pgtable; -} - static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, @@ -876,7 +844,7 @@ static int do_huge_pmd_wp_page_fallback( pmdp_clear_flush_notify(vma, haddr, pmd); /* leave pmd empty until pte is filled */ - pgtable = get_pmd_huge_pte(mm); + pgtable = pgtable_withdraw(mm); pmd_populate(mm, &_pmd, pgtable); for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { @@ -1041,7 +1009,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, if (__pmd_trans_huge_lock(pmd, vma) == 1) { struct page *page; pgtable_t pgtable; - pgtable = get_pmd_huge_pte(tlb->mm); + pgtable = pgtable_withdraw(tlb->mm); page = pmd_page(*pmd); pmd_clear(pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); @@ -1358,7 +1326,7 @@ static int __split_huge_page_map(struct pmd = page_check_address_pmd(page, mm, address, PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); if (pmd) { - pgtable = get_pmd_huge_pte(mm); + pgtable = pgtable_withdraw(mm); pmd_populate(mm, &_pmd, pgtable); for (i = 0, haddr = address; i < HPAGE_PMD_NR; @@ -1971,8 +1939,6 @@ static void collapse_huge_page(struct mm pte_unmap(pte); __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); - VM_BUG_ON(page_count(pgtable) != 1); - VM_BUG_ON(page_mapcount(pgtable) != 0); _pmd = mk_pmd(new_page, vma->vm_page_prot); _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); @@ -1990,7 +1956,7 @@ static void collapse_huge_page(struct mm page_add_new_anon_rmap(new_page, vma, address); set_pmd_at(mm, address, pmd, _pmd); update_mmu_cache(vma, address, _pmd); - prepare_pmd_huge_pte(pgtable, mm); + pgtable_deposit(mm, pgtable); spin_unlock(&mm->page_table_lock); #ifndef CONFIG_NUMA --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -120,3 +120,42 @@ void pmdp_splitting_flush(struct vm_area } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif + +#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +void pgtable_deposit(struct mm_struct *mm, pgtable_t pgtable) +{ + assert_spin_locked(&mm->page_table_lock); + + /* FIFO */ + if (!mm->pmd_huge_pte) + INIT_LIST_HEAD(&pgtable->lru); + else + list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); + mm->pmd_huge_pte = pgtable; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif + +#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* no "address" argument so destroys page coloring of some arch */ +pgtable_t pgtable_withdraw(struct mm_struct *mm) +{ + pgtable_t pgtable; + + assert_spin_locked(&mm->page_table_lock); + + /* FIFO */ + pgtable = mm->pmd_huge_pte; + if (list_empty(&pgtable->lru)) + mm->pmd_huge_pte = NULL; + else { + mm->pmd_huge_pte = list_entry(pgtable->lru.next, + struct page, lru); + list_del(&pgtable->lru); + } + return pgtable; +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif