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Message-ID: <53F2FE4C.7020700@huawei.com>
Date: Tue, 19 Aug 2014 15:35:40 +0800
From: Zhang Zhen <zhenzhang.zhang@...wei.com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
CC: Andrew Morton <akpm@...ux-foundation.org>,
Dave Hansen <dave.hansen@...el.com>,
David Rientjes <rientjes@...gle.com>, <toshi.kani@...com>,
<n-horiguchi@...jp.nec.com>, <wangnan0@...wei.com>,
<linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH v2] memory-hotplug: add sysfs zones_online_to attribute
On 2014/8/18 14:11, Yasuaki Ishimatsu wrote:
> (2014/08/13 13:10), Zhang Zhen wrote:
>> Currently memory-hotplug has two limits:
>> 1. If the memory block is in ZONE_NORMAL, you can change it to
>> ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.
>> 2. If the memory block is in ZONE_MOVABLE, you can change it to
>> ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.
>>
>> With this patch, we can easy to know a memory block can be onlined to
>> which zone, and don't need to know the above two limits.
>>
>> Updated the related Documentation.
>>
>> Change v1 -> v2:
>> - optimize the implementation following Dave Hansen's suggestion
>>
>> Signed-off-by: Zhang Zhen <zhenzhang.zhang@...wei.com>
>> ---
>> Documentation/ABI/testing/sysfs-devices-memory | 8 ++++
>> Documentation/memory-hotplug.txt | 4 +-
>> drivers/base/memory.c | 62 ++++++++++++++++++++++++++
>> include/linux/memory_hotplug.h | 1 +
>> mm/memory_hotplug.c | 2 +-
>> 5 files changed, 75 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
>> index 7405de2..2b2a1d7 100644
>> --- a/Documentation/ABI/testing/sysfs-devices-memory
>> +++ b/Documentation/ABI/testing/sysfs-devices-memory
>> @@ -61,6 +61,14 @@ Users: hotplug memory remove tools
>> http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
>>
>>
>> +What: /sys/devices/system/memory/memoryX/zones_online_to
>> +Date: July 2014
>> +Contact: Zhang Zhen <zhenzhang.zhang@...wei.com>
>> +Description:
>> + The file /sys/devices/system/memory/memoryX/zones_online_to
>> + is read-only and is designed to show which zone this memory block can
>> + be onlined to.
>> +
>> What: /sys/devices/system/memoryX/nodeY
>> Date: October 2009
>> Contact: Linux Memory Management list <linux-mm@...ck.org>
>> diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
>> index 45134dc..5b34e33 100644
>> --- a/Documentation/memory-hotplug.txt
>> +++ b/Documentation/memory-hotplug.txt
>> @@ -155,6 +155,7 @@ Under each memory block, you can see 4 files:
>> /sys/devices/system/memory/memoryXXX/phys_device
>> /sys/devices/system/memory/memoryXXX/state
>> /sys/devices/system/memory/memoryXXX/removable
>> +/sys/devices/system/memory/memoryXXX/zones_online_to
>>
>> 'phys_index' : read-only and contains memory block id, same as XXX.
>> 'state' : read-write
>> @@ -170,6 +171,8 @@ Under each memory block, you can see 4 files:
>> block is removable and a value of 0 indicates that
>> it is not removable. A memory block is removable only if
>> every section in the block is removable.
>> +'zones_online_to' : read-only: designed to show which zone this memory block
>> + can be onlined to.
>>
>> NOTE:
>> These directories/files appear after physical memory hotplug phase.
>> @@ -408,7 +411,6 @@ node if necessary.
>> - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
>> sysctl or new control file.
>> - showing memory block and physical device relationship.
>> - - showing memory block is under ZONE_MOVABLE or not
>> - test and make it better memory offlining.
>> - support HugeTLB page migration and offlining.
>> - memmap removing at memory offline.
>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>> index a2e13e2..b5d693f 100644
>> --- a/drivers/base/memory.c
>> +++ b/drivers/base/memory.c
>> @@ -373,10 +373,71 @@ static ssize_t show_phys_device(struct device *dev,
>> return sprintf(buf, "%d\n", mem->phys_device);
>> }
>>
>> +static int __zones_online_to(unsigned long end_pfn,
>> + struct page *first_page, unsigned long nr_pages)
>> +{
>> + struct zone *zone_next;
>> +
>
>> + /*The mem block is the last block of memory.*/
>> + if (!pfn_valid(end_pfn + 1))
>> + return 1;
>
> The check is not enough if memory has hole as follows:
>
> PFN 0x00 0xd0 0xe0 0xf0
> +-------------+-------------+-------------+
> zone type | Normal | hole | Normal |
> +-------------+-------------+-------------+
>
> In this case, 0xd1 is invalid pfn. But __zones_online_to should return 0
> since 0xe0-0xf0 is Normal zone.
>
> Thanks,
> Yasuaki Ishimatsu
>
You are right, it is not enough.
Here we should make a check as follows.
if ((end_pfn + 1) > zone_end_pfn(page_zone(first_page)))
return 1;
I will send a patch to fix it.
Thanks !
>
>> + zone_next = page_zone(first_page + nr_pages);
>> + if (zone_idx(zone_next) == ZONE_MOVABLE)
>> + return 1;
>> + return 0;
>> +}
>> +
>> +static ssize_t show_zones_online_to(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct memory_block *mem = to_memory_block(dev);
>> + unsigned long start_pfn, end_pfn;
>> + unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
>> + struct page *first_page;
>> + struct zone *zone, *zone_prev;
>> +
>> + start_pfn = section_nr_to_pfn(mem->start_section_nr);
>> + end_pfn = start_pfn + nr_pages;
>> + first_page = pfn_to_page(start_pfn);
>> +
>> + /*The block contains more than one zone can not be offlined.*/
>> + if (!test_pages_in_a_zone(start_pfn, end_pfn))
>> + return sprintf(buf, "none\n");
>> +
>> + zone = page_zone(first_page);
>> +
>> +#ifdef CONFIG_HIGHMEM
>> + if (zone_idx(zone) == ZONE_HIGHMEM) {
>> + if (__zones_online_to(end_pfn, first_page, nr_pages))
>> + return sprintf(buf, "%s %s\n",
>> + zone->name, (zone + 1)->name);
>> + }
>> +#else
>> + if (zone_idx(zone) == ZONE_NORMAL) {
>> + if (__zones_online_to(end_pfn, first_page, nr_pages))
>> + return sprintf(buf, "%s %s\n",
>> + zone->name, (zone + 1)->name);
>> + }
>> +#endif
>> +
>> + if (zone_idx(zone) == ZONE_MOVABLE) {
>> + if (!pfn_valid(start_pfn - nr_pages))
>> + return sprintf(buf, "%s %s\n",
>> + zone->name, (zone - 1)->name);
>> + zone_prev = page_zone(first_page - nr_pages);
>> + if (zone_idx(zone_prev) != ZONE_MOVABLE)
>> + return sprintf(buf, "%s %s\n",
>> + zone->name, (zone - 1)->name);
>> + }
>> +
>> + return sprintf(buf, "%s\n", zone->name);
>> +}
>> +
>> static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
>> static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
>> static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
>> static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
>> +static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
>>
>> /*
>> * Block size attribute stuff
>> @@ -523,6 +584,7 @@ static struct attribute *memory_memblk_attrs[] = {
>> &dev_attr_state.attr,
>> &dev_attr_phys_device.attr,
>> &dev_attr_removable.attr,
>> + &dev_attr_zones_online_to.attr,
>> NULL
>> };
>>
>> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
>> index d9524c4..8f1a419 100644
>> --- a/include/linux/memory_hotplug.h
>> +++ b/include/linux/memory_hotplug.h
>> @@ -84,6 +84,7 @@ extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
>> extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
>> /* VM interface that may be used by firmware interface */
>> extern int online_pages(unsigned long, unsigned long, int);
>> +extern int test_pages_in_a_zone(unsigned long, unsigned long);
>> extern void __offline_isolated_pages(unsigned long, unsigned long);
>>
>> typedef void (*online_page_callback_t)(struct page *page);
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 2ff8c23..29d8693 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1307,7 +1307,7 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
>> /*
>> * Confirm all pages in a range [start, end) is belongs to the same zone.
>> */
>> -static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
>> +int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
>> {
>> unsigned long pfn;
>> struct zone *zone = NULL;
>>
>
>
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