diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/mm/memory.c b/mm/memory.c index 9da8cab1b1b0..b623a249918c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1410,6 +1410,13 @@ no_page_table: return page; } +static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) +{ + return (vma->vm_flags & VM_GROWSDOWN) && + (vma->vm_start == addr) && + !vma_stack_continue(vma->vm_prev, addr); +} + /** * __get_user_pages() - pin user pages in memory * @tsk: task_struct of target task @@ -1488,7 +1495,6 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, vma = find_extend_vma(mm, start); if (!vma && in_gate_area(mm, start)) { unsigned long pg = start & PAGE_MASK; - struct vm_area_struct *gate_vma = get_gate_vma(mm); pgd_t *pgd; pud_t *pud; pmd_t *pmd; @@ -1513,10 +1519,11 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, pte_unmap(pte); return i ? : -EFAULT; } + vma = get_gate_vma(mm); if (pages) { struct page *page; - page = vm_normal_page(gate_vma, start, *pte); + page = vm_normal_page(vma, start, *pte); if (!page) { if (!(gup_flags & FOLL_DUMP) && is_zero_pfn(pte_pfn(*pte))) @@ -1530,12 +1537,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, get_page(page); } pte_unmap(pte); - if (vmas) - vmas[i] = gate_vma; - i++; - start += PAGE_SIZE; - nr_pages--; - continue; + goto next_page; } if (!vma || @@ -1549,6 +1551,13 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, continue; } + /* + * If we don't actually want the page itself, + * and it's the stack guard page, just skip it. + */ + if (!pages && stack_guard_page(vma, start)) + goto next_page; + do { struct page *page; unsigned int foll_flags = gup_flags; @@ -1631,6 +1640,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, flush_anon_page(vma, page, start); flush_dcache_page(page); } +next_page: if (vmas) vmas[i] = vma; i++; |