diff options
| -rw-r--r-- | mm/hugetlb.c | 66 |
1 files changed, 62 insertions, 4 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 7786267da2fe..5b1ab1f427c5 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3728,6 +3728,18 @@ static bool is_hugetlb_entry_hwpoisoned(pte_t pte) return false; } +static void +hugetlb_install_page(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr, + struct page *new_page) +{ + __SetPageUptodate(new_page); + set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1)); + hugepage_add_new_anon_rmap(new_page, vma, addr); + hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm); + ClearHPageRestoreReserve(new_page); + SetHPageMigratable(new_page); +} + int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, struct vm_area_struct *vma) { @@ -3737,6 +3749,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, bool cow = is_cow_mapping(vma->vm_flags); struct hstate *h = hstate_vma(vma); unsigned long sz = huge_page_size(h); + unsigned long npages = pages_per_huge_page(h); struct address_space *mapping = vma->vm_file->f_mapping; struct mmu_notifier_range range; int ret = 0; @@ -3785,6 +3798,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); entry = huge_ptep_get(src_pte); dst_entry = huge_ptep_get(dst_pte); +again: if (huge_pte_none(entry) || !huge_pte_none(dst_entry)) { /* * Skip if src entry none. Also, skip in the @@ -3808,6 +3822,52 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, } set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz); } else { + entry = huge_ptep_get(src_pte); + ptepage = pte_page(entry); + get_page(ptepage); + + /* + * This is a rare case where we see pinned hugetlb + * pages while they're prone to COW. We need to do the + * COW earlier during fork. + * + * When pre-allocating the page or copying data, we + * need to be without the pgtable locks since we could + * sleep during the process. + */ + if (unlikely(page_needs_cow_for_dma(vma, ptepage))) { + pte_t src_pte_old = entry; + struct page *new; + + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + /* Do not use reserve as it's private owned */ + new = alloc_huge_page(vma, addr, 1); + if (IS_ERR(new)) { + put_page(ptepage); + ret = PTR_ERR(new); + break; + } + copy_user_huge_page(new, ptepage, addr, vma, + npages); + put_page(ptepage); + + /* Install the new huge page if src pte stable */ + dst_ptl = huge_pte_lock(h, dst, dst_pte); + src_ptl = huge_pte_lockptr(h, src, src_pte); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + entry = huge_ptep_get(src_pte); + if (!pte_same(src_pte_old, entry)) { + put_page(new); + /* dst_entry won't change as in child */ + goto again; + } + hugetlb_install_page(vma, dst_pte, addr, new); + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + continue; + } + if (cow) { /* * No need to notify as we are downgrading page @@ -3818,12 +3878,10 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, */ huge_ptep_set_wrprotect(src, addr, src_pte); } - entry = huge_ptep_get(src_pte); - ptepage = pte_page(entry); - get_page(ptepage); + page_dup_rmap(ptepage, true); set_huge_pte_at(dst, addr, dst_pte, entry); - hugetlb_count_add(pages_per_huge_page(h), dst); + hugetlb_count_add(npages, dst); } spin_unlock(src_ptl); spin_unlock(dst_ptl); |