diff options
Diffstat (limited to 'mm/khugepaged.c')
-rw-r--r-- | mm/khugepaged.c | 72 |
1 files changed, 35 insertions, 37 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 700f5160f3e4..1d6a9b0b6a9f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -466,7 +466,7 @@ int __khugepaged_enter(struct mm_struct *mm) return -ENOMEM; /* __khugepaged_exit() must not run from under us */ - VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); + VM_BUG_ON_MM(atomic_read(&mm->mm_users) == 0, mm); if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { free_mm_slot(mm_slot); return 0; @@ -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++; } @@ -1495,21 +1484,26 @@ 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); } /* step 4: collapse pmd */ ptl = pmd_lock(vma->vm_mm, pmd); - _pmd = pmdp_collapse_flush(vma, addr, pmd); + _pmd = pmdp_collapse_flush(vma, haddr, pmd); 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) @@ -1538,6 +1532,7 @@ out: static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) { struct vm_area_struct *vma; + struct mm_struct *mm; unsigned long addr; pmd_t *pmd, _pmd; @@ -1566,7 +1561,8 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) continue; if (vma->vm_end < addr + HPAGE_PMD_SIZE) continue; - pmd = mm_find_pmd(vma->vm_mm, addr); + mm = vma->vm_mm; + pmd = mm_find_pmd(mm, addr); if (!pmd) continue; /* @@ -1576,17 +1572,19 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) * mmap_lock while holding page lock. Fault path does it in * reverse order. Trylock is a way to avoid deadlock. */ - if (mmap_write_trylock(vma->vm_mm)) { - spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); - /* assume page table is clear */ - _pmd = pmdp_collapse_flush(vma, addr, pmd); - spin_unlock(ptl); - mmap_write_unlock(vma->vm_mm); - mm_dec_nr_ptes(vma->vm_mm); - pte_free(vma->vm_mm, pmd_pgtable(_pmd)); + if (mmap_write_trylock(mm)) { + if (!khugepaged_test_exit(mm)) { + spinlock_t *ptl = pmd_lock(mm, pmd); + /* assume page table is clear */ + _pmd = pmdp_collapse_flush(vma, addr, pmd); + spin_unlock(ptl); + mm_dec_nr_ptes(mm); + pte_free(mm, pmd_pgtable(_pmd)); + } + mmap_write_unlock(mm); } else { /* Try again later */ - khugepaged_add_pte_mapped_thp(vma->vm_mm, addr); + khugepaged_add_pte_mapped_thp(mm, addr); } } i_mmap_unlock_write(mapping); |