mm/mincore.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/mm/mincore.c b/mm/mincore.c index 218099b5ed31..11ed7064f4eb 100644 --- a/mm/mincore.c +++ b/mm/mincore.c @@ -169,6 +169,13 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, return 0; } +static inline bool can_do_mincore(struct vm_area_struct *vma) +{ + return vma_is_anonymous(vma) + || (vma->vm_file && (vma->vm_file->f_mode & FMODE_WRITE)) + || inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0; +} + /* * Do a chunk of "sys_mincore()". We've already checked * all the arguments, we hold the mmap semaphore: we should @@ -189,8 +196,13 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v vma = find_vma(current->mm, addr); if (!vma || addr < vma->vm_start) return -ENOMEM; - mincore_walk.mm = vma->vm_mm; end = min(vma->vm_end, addr + (pages << PAGE_SHIFT)); + if (!can_do_mincore(vma)) { + unsigned long pages = (end - addr) >> PAGE_SHIFT; + memset(vec, 1, pages); + return pages; + } + mincore_walk.mm = vma->vm_mm; err = walk_page_range(addr, end, &mincore_walk); if (err < 0) return err;