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Date: Thu, 15 Nov 2012 09:24:26 +0800 From: Wen Congyang <wency@...fujitsu.com> To: "Rafael J. Wysocki" <rjw@...k.pl> CC: Toshi Kani <toshi.kani@...com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, linux-acpi@...r.kernel.org, Len Brown <len.brown@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>, Lai Jiangshan <laijs@...fujitsu.com>, Jiang Liu <jiang.liu@...wei.com>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Minchan Kim <minchan.kim@...il.com>, Mel Gorman <mgorman@...e.de>, David Rientjes <rientjes@...gle.com>, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, Jiang Liu <liuj97@...il.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, Christoph Lameter <cl@...ux.com> Subject: Re: [Patch v4 1/7] acpi,memory-hotplug: introduce a mutex lock to protect the list in acpi_memory_device At 11/15/2012 07:34 AM, Rafael J. Wysocki Wrote: > On Tuesday, November 13, 2012 10:04:53 AM Wen Congyang wrote: >> At 11/13/2012 05:00 AM, Toshi Kani Wrote: >>> On Thu, 2012-11-08 at 19:04 +0800, Wen Congyang wrote: >>>> The memory device can be removed by 2 ways: >>>> 1. send eject request by SCI >>>> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject >>>> >>>> This 2 events may happen at the same time, so we may touch >>>> acpi_memory_device.res_list at the same time. This patch >>>> introduce a lock to protect this list. >>> >>> Hi Wen, >>> >>> This race condition is not unique in memory hot-remove as the sysfs >>> eject interface is created for all objects with _EJ0. For CPU >>> hot-remove, I addressed this race condition by making the notify handler >>> to run the hot-remove operation on kacpi_hotplug_wq by calling >>> acpi_os_hotplug_execute(). This serializes the hot-remove operations >>> among the two events since the sysfs eject also runs on >>> kacpi_hotplug_wq. This way is much simpler and is easy to maintain, >>> although it does not allow both operations to run simultaneously (which >>> I do not think we need). Can it be used for memory hot-remove as well? >> >> Good idea. I will update it. > > Still waiting. :-) > > But if you want that in v3.8, please repost ASAP. I think I will send it today. It is in test now. Thanks Wen Congyang > > Thanks, > Rafael > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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