diff options
| -rw-r--r-- | mm/huge_memory.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1ee34ddb46ad..650625390f61 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -708,6 +708,18 @@ static inline struct page *alloc_hugepage(int defrag) } #endif +static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd) +{ + pmd_t entry; + entry = pfn_pmd(huge_zero_pfn, vma->vm_page_prot); + entry = pmd_wrprotect(entry); + entry = pmd_mkhuge(entry); + set_pmd_at(mm, haddr, pmd, entry); + pgtable_trans_huge_deposit(mm, pgtable); + mm->nr_ptes++; +} + int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, unsigned int flags) @@ -785,6 +797,16 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pte_free(dst_mm, pgtable); goto out_unlock; } + /* + * mm->page_table_lock is enough to be sure that huge zero pmd is not + * under splitting since we don't split the page itself, only pmd to + * a page table. + */ + if (is_huge_zero_pmd(pmd)) { + set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd); + ret = 0; + goto out_unlock; + } if (unlikely(pmd_trans_splitting(pmd))) { /* split huge page running from under us */ spin_unlock(&src_mm->page_table_lock); |