diff options
| -rw-r--r-- | mm/khugepaged.c | 44 |
1 files changed, 19 insertions, 25 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 28aae7f45c63..a9aca9b71d6f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1412,7 +1412,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) { unsigned long haddr = addr & HPAGE_PMD_MASK; struct vm_area_struct *vma = find_vma(mm, haddr); - struct page *hpage = NULL; + struct page *hpage; pte_t *start_pte, *pte; pmd_t *pmd, _pmd; spinlock_t *ptl; @@ -1432,9 +1432,17 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) return; + hpage = find_lock_page(vma->vm_file->f_mapping, + linear_page_index(vma, haddr)); + if (!hpage) + return; + + if (!PageHead(hpage)) + goto drop_hpage; + pmd = mm_find_pmd(mm, haddr); if (!pmd) - return; + goto drop_hpage; start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); @@ -1453,30 +1461,11 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) page = vm_normal_page(vma, addr, *pte); - if (!page || !PageCompound(page)) - goto abort; - - if (!hpage) { - hpage = compound_head(page); - /* - * The mapping of the THP should not change. - * - * Note that uprobe, debugger, or MAP_PRIVATE may - * change the page table, but the new page will - * not pass PageCompound() check. - */ - if (WARN_ON(hpage->mapping != vma->vm_file->f_mapping)) - goto abort; - } - /* - * Confirm the page maps to the correct subpage. - * - * Note that uprobe, debugger, or MAP_PRIVATE may change - * the page table, but the new page will not pass - * PageCompound() check. + * Note that uprobe, debugger, or MAP_PRIVATE may change the + * page table, but the new page will not be a subpage of hpage. */ - if (WARN_ON(hpage + i != page)) + if (hpage + i != page) goto abort; count++; } @@ -1495,7 +1484,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) pte_unmap_unlock(start_pte, ptl); /* step 3: set proper refcount and mm_counters. */ - if (hpage) { + if (count) { page_ref_sub(hpage, count); add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); } @@ -1506,10 +1495,15 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) spin_unlock(ptl); mm_dec_nr_ptes(mm); pte_free(mm, pmd_pgtable(_pmd)); + +drop_hpage: + unlock_page(hpage); + put_page(hpage); return; abort: pte_unmap_unlock(start_pte, ptl); + goto drop_hpage; } static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) |