From 4b471e8898c3d0f5c97a3c73ac32d0549fe01c87 Mon Sep 17 00:00:00 2001 From: Kirill A. Shutemov Date: Fri, 15 Jan 2016 16:53:39 -0800 Subject: mm, thp: remove infrastructure for handling splitting PMDs With new refcounting we don't need to mark PMDs splitting. Let's drop code to handle this. Signed-off-by: Kirill A. Shutemov Tested-by: Sasha Levin Tested-by: Aneesh Kumar K.V Acked-by: Vlastimil Babka Acked-by: Jerome Marchand Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Dave Hansen Cc: Mel Gorman Cc: Rik van Riel Cc: Naoya Horiguchi Cc: Steve Capper Cc: Johannes Weiner Cc: Michal Hocko Cc: Christoph Lameter Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 67 ++++++++++++++------------------------------------------ 1 file changed, 16 insertions(+), 51 deletions(-) (limited to 'mm/huge_memory.c') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 72fd53fe2b61..1de7ab5d1004 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -986,15 +986,6 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, goto out_unlock; } - if (unlikely(pmd_trans_splitting(pmd))) { - /* split huge page running from under us */ - spin_unlock(src_ptl); - spin_unlock(dst_ptl); - pte_free(dst_mm, pgtable); - - wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ - goto out; - } src_page = pmd_page(pmd); VM_BUG_ON_PAGE(!PageHead(src_page), src_page); get_page(src_page); @@ -1470,7 +1461,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t orig_pmd; spinlock_t *ptl; - if (__pmd_trans_huge_lock(pmd, vma, &ptl) != 1) + if (!__pmd_trans_huge_lock(pmd, vma, &ptl)) return 0; /* * For architectures like ppc64 we look at deposited pgtable @@ -1504,13 +1495,12 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, return 1; } -int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, +bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, unsigned long old_addr, unsigned long new_addr, unsigned long old_end, pmd_t *old_pmd, pmd_t *new_pmd) { spinlock_t *old_ptl, *new_ptl; - int ret = 0; pmd_t pmd; struct mm_struct *mm = vma->vm_mm; @@ -1519,7 +1509,7 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, (new_addr & ~HPAGE_PMD_MASK) || old_end - old_addr < HPAGE_PMD_SIZE || (new_vma->vm_flags & VM_NOHUGEPAGE)) - goto out; + return false; /* * The destination pmd shouldn't be established, free_pgtables() @@ -1527,15 +1517,14 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, */ if (WARN_ON(!pmd_none(*new_pmd))) { VM_BUG_ON(pmd_trans_huge(*new_pmd)); - goto out; + return false; } /* * We don't have to worry about the ordering of src and dst * ptlocks because exclusive mmap_sem prevents deadlock. */ - ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl); - if (ret == 1) { + if (__pmd_trans_huge_lock(old_pmd, vma, &old_ptl)) { new_ptl = pmd_lockptr(mm, new_pmd); if (new_ptl != old_ptl) spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); @@ -1551,9 +1540,9 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, if (new_ptl != old_ptl) spin_unlock(new_ptl); spin_unlock(old_ptl); + return true; } -out: - return ret; + return false; } /* @@ -1569,7 +1558,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, spinlock_t *ptl; int ret = 0; - if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { + if (__pmd_trans_huge_lock(pmd, vma, &ptl)) { pmd_t entry; bool preserve_write = prot_numa && pmd_write(*pmd); ret = 1; @@ -1600,29 +1589,19 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, } /* - * Returns 1 if a given pmd maps a stable (not under splitting) thp. - * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. + * Returns true if a given pmd maps a thp, false otherwise. * - * Note that if it returns 1, this routine returns without unlocking page - * table locks. So callers must unlock them. + * Note that if it returns true, this routine returns without unlocking page + * table lock. So callers must unlock it. */ -int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, +bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, spinlock_t **ptl) { *ptl = pmd_lock(vma->vm_mm, pmd); - if (likely(pmd_trans_huge(*pmd))) { - if (unlikely(pmd_trans_splitting(*pmd))) { - spin_unlock(*ptl); - wait_split_huge_page(vma->anon_vma, pmd); - return -1; - } else { - /* Thp mapped by 'pmd' is stable, so we can - * handle it as it is. */ - return 1; - } - } + if (likely(pmd_trans_huge(*pmd))) + return true; spin_unlock(*ptl); - return 0; + return false; } /* @@ -1636,7 +1615,6 @@ int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, pmd_t *page_check_address_pmd(struct page *page, struct mm_struct *mm, unsigned long address, - enum page_check_address_pmd_flag flag, spinlock_t **ptl) { pgd_t *pgd; @@ -1659,21 +1637,8 @@ pmd_t *page_check_address_pmd(struct page *page, goto unlock; if (pmd_page(*pmd) != page) goto unlock; - /* - * split_vma() may create temporary aliased mappings. There is - * no risk as long as all huge pmd are found and have their - * splitting bit set before __split_huge_page_refcount - * runs. Finding the same huge pmd more than once during the - * same rmap walk is not a problem. - */ - if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && - pmd_trans_splitting(*pmd)) - goto unlock; - if (pmd_trans_huge(*pmd)) { - VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && - !pmd_trans_splitting(*pmd)); + if (pmd_trans_huge(*pmd)) return pmd; - } unlock: spin_unlock(*ptl); return NULL; -- cgit v1.2.3-55-g7522