From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759253AbZDLHXw (ORCPT ); Sun, 12 Apr 2009 03:23:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757385AbZDLHWj (ORCPT ); Sun, 12 Apr 2009 03:22:39 -0400 Received: from mga14.intel.com ([143.182.124.37]:31531 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756621AbZDLHWh (ORCPT ); Sun, 12 Apr 2009 03:22:37 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,174,1239001200"; d="scan'208";a="130525056" Date: Sun, 12 Apr 2009 15:16:05 +0800 From: Wu Fengguang To: Andrew Morton Cc: LKML , linux-fsdevel@vger.kernel.org, Chenfeng Xu Subject: [RFC][PATCH] vfs: check inode size on no_cached_page Message-ID: <20090412071605.GA14058@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [This patch may not necessarily be merged, but at least we should be aware of the problem.] When user space requests past-EOF data, do_generic_file_read() will issue a bonus readpage call, which may be unfavorable. do_generic_file_read: -> find_page: -> find_get_page() = NULL -> page_cache_sync_readahead() -> find_get_page() = NULL -> no_cached_page: -> readpage: -> nfs_readpage() = error -> readpage_error: Reported-by: Xu Chenfeng Signed-off-by: Wu Fengguang --- mm/filemap.c | 5 +++++ 1 file changed, 5 insertions(+) --- mm.orig/mm/filemap.c +++ mm/mm/filemap.c @@ -1269,6 +1269,11 @@ readpage_error: goto out; no_cached_page: + isize = i_size_read(inode); + end_index = (isize - 1) >> PAGE_CACHE_SHIFT; + if (unlikely(!isize || index > end_index)) + goto out; + /* * Ok, it wasn't cached, so we need to create a new * page..