diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 37 |
1 files changed, 30 insertions, 7 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4acf55b31f7c..f283cb7c480e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -874,8 +874,6 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) return VM_FAULT_FALLBACK; - if (vma->vm_flags & VM_LOCKED) - return VM_FAULT_FALLBACK; if (unlikely(anon_vma_prepare(vma))) return VM_FAULT_OOM; if (unlikely(khugepaged_enter(vma, vma->vm_flags))) @@ -1344,7 +1342,20 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, update_mmu_cache_pmd(vma, addr, pmd); } if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { - if (page->mapping && trylock_page(page)) { + /* + * We don't mlock() pte-mapped THPs. This way we can avoid + * leaking mlocked pages into non-VM_LOCKED VMAs. + * + * In most cases the pmd is the only mapping of the page as we + * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for + * writable private mappings in populate_vma_page_range(). + * + * The only scenario when we have the page shared here is if we + * mlocking read-only mapping shared over fork(). We skip + * mlocking such pages. + */ + if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && + page->mapping && trylock_page(page)) { lru_add_drain(); if (page->mapping) mlock_vma_page(page); @@ -2209,8 +2220,6 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || (vma->vm_flags & VM_NOHUGEPAGE)) return false; - if (vma->vm_flags & VM_LOCKED) - return false; if (!vma->anon_vma || vma->vm_ops) return false; if (is_vma_temporary_stack(vma)) @@ -2851,14 +2860,28 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, { spinlock_t *ptl; struct mm_struct *mm = vma->vm_mm; + struct page *page = NULL; unsigned long haddr = address & HPAGE_PMD_MASK; mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); ptl = pmd_lock(mm, pmd); - if (likely(pmd_trans_huge(*pmd))) - __split_huge_pmd_locked(vma, pmd, haddr, false); + if (unlikely(!pmd_trans_huge(*pmd))) + goto out; + page = pmd_page(*pmd); + __split_huge_pmd_locked(vma, pmd, haddr, false); + if (PageMlocked(page)) + get_page(page); + else + page = NULL; +out: spin_unlock(ptl); mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); + if (page) { + lock_page(page); + munlock_vma_page(page); + unlock_page(page); + put_page(page); + } } static void split_huge_pmd_address(struct vm_area_struct *vma, |