From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756553Ab2IIXU5 (ORCPT ); Sun, 9 Sep 2012 19:20:57 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51555 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756440Ab2IIXRT (ORCPT ); Sun, 9 Sep 2012 19:17:19 -0400 Message-Id: <20120909224153.644601479@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 09 Sep 2012 23:42:10 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Will Deacon , Catalin Marinas , Russell King Subject: [ 20/95] ARM: 7488/1: mm: use 5 bits for swapfile type encoding In-Reply-To: <20120909224150.641491654@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon commit f5f2025ef3e2cdb593707cbf87378761f17befbe upstream. Page migration encodes the pfn in the offset field of a swp_entry_t. For LPAE, we support physical addresses of up to 36 bits (due to sparsemem limitations with the size of page flags), requiring 24 bits to represent a pfn. A further 3 bits are used to encode a swp_entry into a pte, leaving 5 bits for the type field. Furthermore, the core code defines MAX_SWAPFILES_SHIFT as 5, so the additional type bit does not get used. This patch reduces the width of the type field to 5 bits, allowing us to create up to 31 swapfiles of 64GB each. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Ben Hutchings --- arch/arm/include/asm/pgtable.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index d88f9f0..41dc31f 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -253,13 +253,13 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) * * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 - * <--------------- offset --------------------> <- type --> 0 0 0 + * <--------------- offset ----------------------> < type -> 0 0 0 * - * This gives us up to 63 swap files and 32GB per swap file. Note that + * This gives us up to 31 swap files and 64GB per swap file. Note that * the offset field is always non-zero. */ #define __SWP_TYPE_SHIFT 3 -#define __SWP_TYPE_BITS 6 +#define __SWP_TYPE_BITS 5 #define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1) #define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)