linux-kernel - Re: [Patch v5 0/7] acpi,memory-hotplug: implement framework for hot removing memory

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Date:	Fri, 16 Nov 2012 02:28:14 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Wen Congyang <wency@...fujitsu.com>
Cc:	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>,
	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>,
	Toshi Kani <toshi.kani@...com>
Subject: Re: [Patch v5 0/7] acpi,memory-hotplug: implement framework for hot removing memory

On Friday, November 16, 2012 10:07:49 AM Yasuaki Ishimatsu wrote:
> Hi Rafael,
> 
> 2012/11/16 9:28, Rafael J. Wysocki wrote:
> > On Thursday, November 15, 2012 02:59:30 PM 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
> >>
> >> In the 1st case, acpi_memory_disable_device() will be called.
> >> In the 2nd case, acpi_memory_device_remove() will be called.
> >> acpi_memory_device_remove() will also be called when we unbind the
> >> memory device from the driver acpi_memhotplug or a driver initialization
> >> fails.
> >>
> >> acpi_memory_disable_device() has already implemented a code which
> >> offlines memory and releases acpi_memory_info struct . But
> >> acpi_memory_device_remove() has not implemented it yet.
> >>
> >> So the patch prepares the framework for hot removing memory and
> >> adds the framework into acpi_memory_device_remove().
> >>
> >> We may hotremove the memory device by this 2 ways at the same time.
> >> So we remove the function acpi_memory_disable_device(), and use
> >> acpi_bus_hot_remove_device() which is used by 2nd case to implement it.
> >> We lock device in acpi_bus_hot_remove_device(), so there is no
> >> need to add lock in acpi_memhotplug.
> >>
> >> The last version of this patchset is here:
> >> https://lkml.org/lkml/2012/11/8/121
> >>
> >> Note:
> >> 1. The following commit in pm tree can be dropped now(The other two patches
> >>     are already dropped):
> >>     54c4c7db6cb94d7d1217df6d7fca6847c61744ab
> >> 2. This patchset requires the following patch(It is in pm tree now)
> >>     https://lkml.org/lkml/2012/11/1/225
> >>
> >> Changes from v4 to v5:
> >> 1. patch2: new patch. use acpi_bus_hot_remove_device() to implement memory
> >>     device hotremove.
> >>
> >> Changes from v3 to v4:
> >> 1. patch1: unlock list_lock when removing memory fails.
> >> 2. patch2: just rebase them
> >> 3. patch3-7: these patches are in -mm tree, and they conflict with this
> >>     patchset, so Adrew Morton drop them from -mm tree. I rebase and merge
> >>     them into this patchset.
> >>
> >> Wen Congyang (6):
> >>    acpi,memory-hotplug: deal with eject request in hotplug queue
> >>    acpi_memhotplug.c: fix memory leak when memory device is unbound from
> >>      the module acpi_memhotplug
> >>    acpi_memhotplug.c: free memory device if acpi_memory_enable_device()
> >>      failed
> >>    acpi_memhotplug.c: don't allow to eject the memory device if it is
> >>      being used
> >>    acpi_memhotplug.c: bind the memory device when the driver is being
> >>      loaded
> >>    acpi_memhotplug.c: auto bind the memory device which is hotplugged
> >>      before the driver is loaded
> >>
> >> Yasuaki Ishimatsu (1):
> >>    acpi,memory-hotplug : add memory offline code to
> >>      acpi_memory_device_remove()
> >
> > Well, I have tried _really_ hard to apply this patchset, but pretty much
> > none of the patches except for [1/7] applied for me.  I have no idea what
> > tree they are against, but I'm pretty sure it's not my tree.
> >
> > I _have_ applied patches [1-4/7] and pushed them to linux-pm.git/linux-next.
> 
> I checked your tree and found a mistake.
> You merged a following patch into your tree.
> 
> commitid:2ba281f1
> ACPI / memory-hotplug: introduce a mutex lock to protect the list
> in acpi_memory_device
> 
> But it is wrong.
> 
> [1/7] patch is "acpi,memory-hotplug : add memory offline code to
> acpi_memory_device_remove()". So we would like you to merge it
> instead of commitid:2ba281f1.

Yes, I've found it too.

Now applied patches [1-6/7], because I agree with Toshi Kani that patch [7/7]
goes too far, so I'm not going to apply it.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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