From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id E85746B0257 for ; Mon, 13 Jul 2015 06:54:23 -0400 (EDT) Received: by pactm7 with SMTP id tm7so205676697pac.2 for ; Mon, 13 Jul 2015 03:54:23 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTP id h14si27815232pdl.168.2015.07.13.03.54.17 for ; Mon, 13 Jul 2015 03:54:17 -0700 (PDT) From: "Kirill A. Shutemov" Subject: [PATCH 3/5] mm: make sure all file VMAs have ->vm_ops set Date: Mon, 13 Jul 2015 13:54:10 +0300 Message-Id: <1436784852-144369-4-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1436784852-144369-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1436784852-144369-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Oleg Nesterov Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" We rely on vma->vm_ops == NULL to detect anonymous VMA: see vma_is_anonymous(), but some drivers doesn't set ->vm_ops. As result we can end up with anonymous page in private file mapping. That's should not lead to serious misbehaviour, but nevertheless is wrong. Let's fix by setting up dummy ->vm_ops for file mmapping if f_op->mmap() didn't set its own. The patch also adds sanity check into __vma_link_rb(). It will help catch broken VMAs which inserted directly into mm_struct via insert_vm_struct(). Signed-off-by: Kirill A. Shutemov --- mm/mmap.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 30904c16b7d3..4ce7a6f33db0 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -612,6 +612,8 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm, void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, struct rb_node **rb_link, struct rb_node *rb_parent) { + WARN_ONCE(vma->vm_file && !vma->vm_ops, "missing vma->vm_ops"); + /* Update tracking information for the gap following the new vma. */ if (vma->vm_next) vma_gap_update(vma->vm_next); @@ -1638,6 +1640,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr, */ WARN_ON_ONCE(addr != vma->vm_start); + /* All file mapping must have ->vm_ops set */ + if (!vma->vm_ops) { + static const struct vm_operations_struct dummy_ops = {}; + vma->vm_ops = &dummy_ops; + } + addr = vma->vm_start; vm_flags = vma->vm_flags; } else if (vm_flags & VM_SHARED) { -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org