From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759259Ab3GaIUW (ORCPT ); Wed, 31 Jul 2013 04:20:22 -0400 Received: from relay.parallels.com ([195.214.232.42]:55028 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759172Ab3GaIQp (ORCPT ); Wed, 31 Jul 2013 04:16:45 -0400 Message-ID: <51F8C7CC.6010703@parallels.com> Date: Wed, 31 Jul 2013 12:16:12 +0400 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Cyrill Gorcunov , CC: , , , , , , , , , , Subject: Re: [patch 1/2] [PATCH] mm: Save soft-dirty bits on swapped pages References: <20130730204154.407090410@gmail.com> <20130730204654.844299768@gmail.com> In-Reply-To: <20130730204654.844299768@gmail.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.30.16.114] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/31/2013 12:41 AM, Cyrill Gorcunov wrote: > Andy Lutomirski reported that in case if a page with _PAGE_SOFT_DIRTY > bit set get swapped out, the bit is getting lost and no longer > available when pte read back. > > To resolve this we introduce _PTE_SWP_SOFT_DIRTY bit which is > saved in pte entry for the page being swapped out. When such page > is to be read back from a swap cache we check for bit presence > and if it's there we clear it and restore the former _PAGE_SOFT_DIRTY > bit back. > > One of the problem was to find a place in pte entry where we can > save the _PTE_SWP_SOFT_DIRTY bit while page is in swap. The > _PAGE_PSE was chosen for that, it doesn't intersect with swap > entry format stored in pte. > > Reported-by: Andy Lutomirski > Signed-off-by: Cyrill Gorcunov Acked-by: Pavel Emelyanov