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Date: Fri, 13 Jul 2012 11:35:13 +0800
From: Wen Congyang <wency@...fujitsu.com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
CC: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com,
benh@...nel.crashing.org, paulus@...ba.org, cl@...ux.com,
minchan.kim@...il.com, akpm@...ux-foundation.org,
kosaki.motohiro@...fujitsu.com
Subject: Re: [RFC PATCH v3 2/13] memory-hotplug : add physical memory hotplug
code to acpi_memory_device_remove
At 07/09/2012 06:24 PM, Yasuaki Ishimatsu Wrote:
> acpi_memory_device_remove() has been prepared to remove physical memory.
> But, the function only frees acpi_memory_device currentlry.
>
> The patch adds following functions into acpi_memory_device_remove():
> - offline memory
> - remove physical memory (only return -EBUSY)
> - free acpi_memory_device
>
> CC: David Rientjes <rientjes@...gle.com>
> CC: Jiang Liu <liuj97@...il.com>
> CC: Len Brown <len.brown@...el.com>
> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> CC: Paul Mackerras <paulus@...ba.org>
> CC: Christoph Lameter <cl@...ux.com>
> Cc: Minchan Kim <minchan.kim@...il.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> CC: Wen Congyang <wency@...fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
>
> ---
> drivers/acpi/acpi_memhotplug.c | 26 +++++++++++++++++++++++++-
> drivers/base/memory.c | 39 +++++++++++++++++++++++++++++++++++++++
> include/linux/memory.h | 5 +++++
> include/linux/memory_hotplug.h | 1 +
> mm/memory_hotplug.c | 8 ++++++++
> 5 files changed, 78 insertions(+), 1 deletion(-)
>
> Index: linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/acpi/acpi_memhotplug.c 2012-07-09 18:08:29.946888653 +0900
> +++ linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c 2012-07-09 18:08:43.470719531 +0900
> @@ -29,6 +29,7 @@
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/types.h>
> +#include <linux/memory.h>
> #include <linux/memory_hotplug.h>
> #include <linux/slab.h>
> #include <acpi/acpi_drivers.h>
> @@ -452,12 +453,35 @@ static int acpi_memory_device_add(struct
> static int acpi_memory_device_remove(struct acpi_device *device, int type)
> {
> struct acpi_memory_device *mem_device = NULL;
> -
> + struct acpi_memory_info *info, *tmp;
> + int result;
> + int node;
>
> if (!device || !acpi_driver_data(device))
> return -EINVAL;
>
> mem_device = acpi_driver_data(device);
> +
> + node = acpi_get_node(mem_device->device->handle);
> +
> + list_for_each_entry_safe(info, tmp, &mem_device->res_list, list) {
> + if (!info->enabled)
> + continue;
> +
> + if (!is_memblk_offline(info->start_addr, info->length)) {
> + result = offline_memory(info->start_addr, info->length);
> + if (result)
> + return result;
> + }
> +
> + result = remove_memory(node, info->start_addr, info->length);
The user may online the memory between offline_memory() and remove_memory().
So I think we should lock memory hotplug before check the memory's status
and release it after remove_memory().
Thanks
Wen Congyang
> + if (result)
> + return result;
> +
> + list_del(&info->list);
> + kfree(info);
> + }
> +
> kfree(mem_device);
>
> return 0;
> Index: linux-3.5-rc6/include/linux/memory_hotplug.h
> ===================================================================
> --- linux-3.5-rc6.orig/include/linux/memory_hotplug.h 2012-07-09 18:08:29.955888542 +0900
> +++ linux-3.5-rc6/include/linux/memory_hotplug.h 2012-07-09 18:08:43.471719518 +0900
> @@ -233,6 +233,7 @@ static inline int is_mem_section_removab
> extern int mem_online_node(int nid);
> extern int add_memory(int nid, u64 start, u64 size);
> extern int arch_add_memory(int nid, u64 start, u64 size);
> +extern int remove_memory(int nid, u64 start, u64 size);
> extern int offline_memory(u64 start, u64 size);
> extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
> int nr_pages);
> Index: linux-3.5-rc6/mm/memory_hotplug.c
> ===================================================================
> --- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-09 18:08:29.953888567 +0900
> +++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-09 18:08:43.476719455 +0900
> @@ -659,6 +659,14 @@ out:
> }
> EXPORT_SYMBOL_GPL(add_memory);
>
> +int remove_memory(int nid, u64 start, u64 size)
> +{
> + return -EBUSY;
> +
> +}
> +EXPORT_SYMBOL_GPL(remove_memory);
> +
> +
> #ifdef CONFIG_MEMORY_HOTREMOVE
> /*
> * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
> Index: linux-3.5-rc6/drivers/base/memory.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/base/memory.c 2012-07-09 18:08:29.947888640 +0900
> +++ linux-3.5-rc6/drivers/base/memory.c 2012-07-09 18:10:54.880076739 +0900
> @@ -70,6 +70,45 @@ void unregister_memory_isolate_notifier(
> }
> EXPORT_SYMBOL(unregister_memory_isolate_notifier);
>
> +bool is_memblk_offline(unsigned long start, unsigned long size)
> +{
> + struct memory_block *mem = NULL;
> + struct mem_section *section;
> + unsigned long start_pfn, end_pfn;
> + unsigned long pfn, section_nr;
> +
> + start_pfn = PFN_DOWN(start);
> + end_pfn = start_pfn + PFN_DOWN(start);
> +
> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> + section_nr = pfn_to_section_nr(pfn);
> + if (!present_section_nr(section_nr));
> + continue;
> +
> + section = __nr_to_section(section_nr);
> + /* same memblock? */
> + if (mem)
> + if((section_nr >= mem->start_section_nr) &&
> + (section_nr <= mem->end_section_nr))
> + continue;
> +
> + mem = find_memory_block_hinted(section, mem);
> + if (!mem)
> + continue;
> + if (mem->state == MEM_OFFLINE)
> + continue;
> +
> + kobject_put(&mem->dev.kobj);
> + return false;
> + }
> +
> + if (mem)
> + kobject_put(&mem->dev.kobj);
> +
> + return true;
> +}
> +EXPORT_SYMBOL(is_memblk_offline);
> +
> /*
> * register_memory - Setup a sysfs device for a memory block
> */
> Index: linux-3.5-rc6/include/linux/memory.h
> ===================================================================
> --- linux-3.5-rc6.orig/include/linux/memory.h 2012-07-08 09:23:56.000000000 +0900
> +++ linux-3.5-rc6/include/linux/memory.h 2012-07-09 18:08:43.484719355 +0900
> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify(
> {
> return 0;
> }
> +static inline bool is_memblk_offline(unsigned long start, unsigned long size)
> +{
> + return false;
> +}
> #else
> extern int register_memory_notifier(struct notifier_block *nb);
> extern void unregister_memory_notifier(struct notifier_block *nb);
> @@ -120,6 +124,7 @@ extern int memory_isolate_notify(unsigne
> extern struct memory_block *find_memory_block_hinted(struct mem_section *,
> struct memory_block *);
> extern struct memory_block *find_memory_block(struct mem_section *);
> +extern bool is_memblk_offline(unsigned long start, unsigned long size);
> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
> enum mem_add_context { BOOT, HOTPLUG };
> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
>
>
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