From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756930Ab0C3XVd (ORCPT ); Tue, 30 Mar 2010 19:21:33 -0400 Received: from kroah.org ([198.145.64.141]:46150 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932558Ab0C3XUP (ORCPT ); Tue, 30 Mar 2010 19:20:15 -0400 X-Mailbox-Line: From linux@linux.site Tue Mar 30 15:48:03 2010 Message-Id: <20100330224803.432266659@linux.site> User-Agent: quilt/0.47-14.9 Date: Tue, 30 Mar 2010 15:41:40 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mel Gorman , Greg Kroah-Hartman Subject: [066/156] tty: Take a 256 byte padding into account when buffering below sub-page units In-Reply-To: <20100330230630.GA28824@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mel Gorman commit 352fa6ad16b89f8ffd1a93b4419b1a8f2259feab upstream. The TTY layer takes some care to ensure that only sub-page allocations are made with interrupts disabled. It does this by setting a goal of "TTY_BUFFER_PAGE" to allocate. Unfortunately, while TTY_BUFFER_PAGE takes the size of tty_buffer into account, it fails to account that tty_buffer_find() rounds the buffer size out to the next 256 byte boundary before adding on the size of the tty_buffer. This patch adjusts the TTY_BUFFER_PAGE calculation to take into account the size of the tty_buffer and the padding. Once applied, tty_buffer_alloc() should not require high-order allocations. Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman --- include/linux/tty.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -70,12 +70,13 @@ struct tty_buffer { /* * We default to dicing tty buffer allocations to this many characters - * in order to avoid multiple page allocations. We assume tty_buffer itself - * is under 256 bytes. See tty_buffer_find for the allocation logic this - * must match + * in order to avoid multiple page allocations. We know the size of + * tty_buffer itself but it must also be taken into account that the + * the buffer is 256 byte aligned. See tty_buffer_find for the allocation + * logic this must match */ -#define TTY_BUFFER_PAGE ((PAGE_SIZE - 256) / 2) +#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF) struct tty_bufhead {