Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966561Ab3HHXDs (ORCPT ); Thu, 8 Aug 2013 19:03:48 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:33090 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966339Ab3HHXDq (ORCPT ); Thu, 8 Aug 2013 19:03:46 -0400 From: "Rafael J. Wysocki" To: Toshi Kani Cc: Yasuaki Ishimatsu , rafael.j.wysocki@intel.com, vasilis.liaskovitis@profitbricks.com, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, tangchen@cn.fujitsu.com, wency@cn.fujitsu.com Subject: Re: Cannot hot remove a memory device Date: Fri, 09 Aug 2013 01:14:04 +0200 Message-ID: <2966692.KbMK5bTkda@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.11.0-rc4+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <1376002242.10300.235.camel@misato.fc.hp.com> References: <51FA1E41.20304@jp.fujitsu.com> <13789925.vhhiTlyGIy@vostro.rjw.lan> <1376002242.10300.235.camel@misato.fc.hp.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3100 Lines: 61 On Thursday, August 08, 2013 04:50:42 PM Toshi Kani wrote: > On Fri, 2013-08-09 at 00:12 +0200, Rafael J. Wysocki wrote: > > On Thursday, August 08, 2013 11:15:20 AM Toshi Kani wrote: > > > On Fri, 2013-08-02 at 18:04 -0600, Toshi Kani wrote: > > > > On Sat, 2013-08-03 at 01:43 +0200, Rafael J. Wysocki wrote: > > > > > On Friday, August 02, 2013 03:46:15 PM Toshi Kani wrote: > > > > > > On Thu, 2013-08-01 at 23:43 +0200, Rafael J. Wysocki wrote: > > > : > > > > > > I think it fails with -EINVAL at the place with dev_warn(dev, "ACPI > > > > > > handle is already set\n"). When two ACPI memory objects associate with > > > > > > a same memory block, the bind procedure of the 2nd ACPI memory object > > > > > > sees that ACPI_HANDLE(dev) is already set to the 1st ACPI memory object. > > > > > > > > > > That sound's plausible, but I wonder how we can fix that? > > > > > > > > > > There's no way for a single physical device to have two different ACPI > > > > > "companions". It looks like the memory blocks should be 64 M each in that > > > > > case. Or we need to create two child devices for each memory block and > > > > > associate each of them with an ACPI object. That would lead to complications > > > > > in the user space interface, though. > > > > > > > > Right. Even bigger issue is that I do not think __add_pages() and > > > > __remove_pages() can add / delete a memory chunk that is less than > > > > 128MB. 128MB is the granularity of them. So, we may just have to fail > > > > this case gracefully. > > > > > > FYI: I have submitted the patch blow to close this part of the issue... > > > > > > https://lkml.org/lkml/2013/8/8/396 > > > > That looks good to me, but we'd still need to make it possible to have > > memory blocks smaller than 128 MB ... > > Do you mean acpi_bind_one() needs to be able to handle such case? If > so, it should not be a problem since a memory block device won't be > created when add_memory() fails with the change above. So, there is no > binding to be done. If you mean add_memory() needs to be able to handle > a smaller range, that's quite a tough one unless we make the section > size smaller. > > BTW, when add_memory() fails, the memory hot-add request still succeeds > with no driver attached. This seems logical, but the added device is > useless when no handler is attached. And it does not allow ejecting the > device with no handler. I am not too worry about this since this is a > rare case, but it reminded me that the framework won't handle rollback. That is a valid observation. Perhaps we should add a flag that will cause acpi_bus_offline_companions() to fail immediately if that flag is set for the given device? Then, acpi_memory_enable_device() could set that flag for mem_device->device when either add_memory() or acpi_bind_memory_blocks() fails? Rafael -- 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/