From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933038Ab2KNRba (ORCPT ); Wed, 14 Nov 2012 12:31:30 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:43400 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932978Ab2KNRb3 (ORCPT ); Wed, 14 Nov 2012 12:31:29 -0500 From: Joonsoo Kim To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim Subject: [RFC PATCH] mm: WARN_ON_ONCE if f_op->mmap() change vma's start address Date: Thu, 15 Nov 2012 02:28:52 +0900 Message-Id: <1352914132-18445-1-git-send-email-js1304@gmail.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During reviewing the source code, I found a comment which mention that after f_op->mmap(), vma's start address can be changed. I didn't verify that it is really possible, because there are so many f_op->mmap() implementation. But if there are some mmap() which change vma's start address, it is possible error situation, because we already prepare prev vma, rb_link and rb_parent and these are related to original address. So add WARN_ON_ONCE for finding that this situtation really happens. Signed-off-by: Joonsoo Kim diff --git a/mm/mmap.c b/mm/mmap.c index 2d94235..36567b7 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1333,7 +1333,11 @@ munmap_back: * * Answer: Yes, several device drivers can do it in their * f_op->mmap method. -DaveM + * Bug: If addr is changed, prev, rb_link, rb_parent should + * be updated for vma_link() */ + WARN_ON_ONCE(addr != vma->vm_start); + addr = vma->vm_start; pgoff = vma->vm_pgoff; vm_flags = vma->vm_flags; -- 1.7.9.5