Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758832Ab2BJAIx (ORCPT ); Thu, 9 Feb 2012 19:08:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:14978 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758807Ab2BJAIu (ORCPT ); Thu, 9 Feb 2012 19:08:50 -0500 Subject: Re: [PATCH] ACPI: Fix logic for removing mappings in 'acpi_unmap' From: Myron Stowe To: Bjorn Helgaas Cc: Myron Stowe , lenb@kernel.org, linux-acpi@vger.kernel.org, ying.huang@intel.com, tony.luck@intel.com, trenn@suse.de, linux-kernel@vger.kernel.org, mingo@elte.hu In-Reply-To: References: <20120209163641.26858.59399.stgit@amt.stowe> Content-Type: text/plain; charset="UTF-8" Date: Thu, 09 Feb 2012 17:08:38 -0700 Message-ID: <1328832518.2404.86.camel@zim.stowe> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2083 Lines: 58 On Thu, 2012-02-09 at 08:42 -0800, Bjorn Helgaas wrote: > On Thu, Feb 9, 2012 at 8:36 AM, Myron Stowe wrote: > > From: Myron Stowe > > > > Make sure the removal of mappings uses the same logic that put the > > mappings in place. > > > > Signed-off-by: Myron Stowe > > --- > > > > drivers/acpi/osl.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c > > index 412a1e0..5aef087 100644 > > --- a/drivers/acpi/osl.c > > +++ b/drivers/acpi/osl.c > > @@ -347,7 +347,7 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr) > > unsigned long pfn; > > > > pfn = pg_off >> PAGE_SHIFT; > > - if (page_is_ram(pfn)) > > + if (should_use_kmap(pfn)) > > kunmap(pfn_to_page(pfn)); > > else > > iounmap(vaddr); > > > > Whatever happened to the question of why we have arch-specific > ioremap() behavior? It's good to make map/unmap symmetric, but it'd > be better to get rid of the ioremap/kmap hack. +cc ingo We never received any explanation for why ioremap() failed for Ying with RAM on x86. Last I saw Ying asked Ingo for some input here but there was never any reply - http://marc.info/?l=linux-acpi&m=132788392604738&w=2 I like your idea of possibly changing ioremap's implementation so that it would handle requests related to RAM - by using kmap() internally when necessary - so that a *user* wouldn't need to care what architecture we're on. I, however, feel like I don't have enough experience with the memory management subsystem to know if such a tactic would fly or not so was uncomfortable proceeding along those lines. As a result, I just wanted to get this in for the meantime. Myron > > Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/