From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758781AbZCBJdV (ORCPT ); Mon, 2 Mar 2009 04:33:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756930AbZCBJdJ (ORCPT ); Mon, 2 Mar 2009 04:33:09 -0500 Received: from ti-out-0910.google.com ([209.85.142.189]:28833 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757918AbZCBJdI (ORCPT ); Mon, 2 Mar 2009 04:33:08 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:x-mailer:mime-version :content-type:content-transfer-encoding; b=OQomYc1BumGEvJYzcO7YVQAFaHsYjr6F/Eu3nKyXU7Gqc6TC8NL61CLpGLlGHtQU3L h+Wv1pzZ+yQHQqQFFtmlx3q73CoJl3PtWNwQzrQAcvv63dmVITpcfPocP5piarB7yCbX 7HJyLQCRpXnaILk71o5eCPTsgYGozPRpZ1Qqw= Date: Mon, 2 Mar 2009 18:31:48 +0900 From: MinChan Kim To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mmtom : add VM_BUG_ON in __get_free_pages Message-Id: <20090302183148.a4dfcc22.minchan.kim@barrios-desktop> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The __get_free_pages is used in many place. Also, driver developers can use it freely due to export function. Some developers might use it to allocate high pages by mistake. The __get_free_pages can allocate high page using alloc_pages, but it can't return linear address for high page. Even worse, in this csse, caller can't free page which are there in high zone. So, It would be better to add VM_BUG_ON. It's based on mmtom 2009-02-27-13-54. Signed-off-by: MinChan Kim --- mm/page_alloc.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8294107..381056b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1681,6 +1681,13 @@ EXPORT_SYMBOL(__alloc_pages_internal); unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order) { struct page * page; + + /* + * __get_free_pages() returns a 32-bit address, which cannot represent + * a highmem page + */ + VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0); + page = alloc_pages(gfp_mask, order); if (!page) return 0; -- 1.5.4.3 -- Kinds Regards MinChan Kim