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Date: Wed, 27 Aug 2014 09:55:00 +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>,
Toshi Kani <toshi.kani@...com>,
David Rientjes <rientjes@...gle.com>, <wangnan0@...wei.com>,
<linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH] memory-hotplug: fix not enough check of valid_zones
On 2014/8/26 18:23, Yasuaki Ishimatsu wrote:
> (2014/08/26 18:57), Zhang Zhen wrote:
>> As Yasuaki Ishimatsu described the check here is not enough
>> if memory has hole as follows:
>>
>> PFN 0x00 0xd0 0xe0 0xf0
>> +-------------+-------------+-------------+
>> zone type | Normal | hole | Normal |
>> +-------------+-------------+-------------+
>> In this case, the check can't guarantee that this is "the last
>> block of memory".
>> The check of ZONE_MOVABLE has the same problem.
>>
>> Change the interface name to valid_zones according to most pepole's
>> suggestion.
>>
>> Sample output of the sysfs files:
>> memory0/valid_zones: none
>> memory1/valid_zones: DMA32
>> memory2/valid_zones: DMA32
>> memory3/valid_zones: DMA32
>> memory4/valid_zones: Normal
>> memory5/valid_zones: Normal
>> memory6/valid_zones: Normal Movable
>> memory7/valid_zones: Movable Normal
>> memory8/valid_zones: Movable
>
> The patch has two changes:
> - change sysfs interface name
> - change check of ZONE_MOVABLE
> So please separate them.
>
Ok, i will separate them.
Thanks!
>> 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 | 42 ++++++--------------------
>> 3 files changed, 15 insertions(+), 39 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
>> index 2b2a1d7..deef3b5 100644
>> --- a/Documentation/ABI/testing/sysfs-devices-memory
>> +++ b/Documentation/ABI/testing/sysfs-devices-memory
>> @@ -61,13 +61,13 @@ Users: hotplug memory remove tools
>> http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
>>
>>
>> -What: /sys/devices/system/memory/memoryX/zones_online_to
>> +What: /sys/devices/system/memory/memoryX/valid_zones
>> 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.
>> + The file /sys/devices/system/memory/memoryX/valid_zones 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
>> diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
>> index 5b34e33..947229c 100644
>> --- a/Documentation/memory-hotplug.txt
>> +++ b/Documentation/memory-hotplug.txt
>> @@ -155,7 +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
>> +/sys/devices/system/memory/memoryXXX/valid_zones
>>
>> 'phys_index' : read-only and contains memory block id, same as XXX.
>> 'state' : read-write
>> @@ -171,7 +171,7 @@ 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
>> +'valid_zones' : read-only: designed to show which zone this memory block
>> can be onlined to.
>>
>> NOTE:
>> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>> index ccaf37c..efd456c 100644
>> --- a/drivers/base/memory.c
>> +++ b/drivers/base/memory.c
>> @@ -374,21 +374,7 @@ static ssize_t show_phys_device(struct device *dev,
>> }
>>
>> #ifdef CONFIG_MEMORY_HOTREMOVE
>> -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;
>> - 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,
>> +static ssize_t show_valid_zones(struct device *dev,
>> struct device_attribute *attr, char *buf)
>> {
>> struct memory_block *mem = to_memory_block(dev);
>> @@ -407,33 +393,23 @@ static ssize_t show_zones_online_to(struct device *dev,
>>
>> zone = page_zone(first_page);
>>
>> -#ifdef CONFIG_HIGHMEM
>> - if (zone_idx(zone) == ZONE_HIGHMEM) {
>> - if (__zones_online_to(end_pfn, first_page, nr_pages))
>> + if (zone_idx(zone) == ZONE_MOVABLE - 1) {
>> + /*The mem block is the last memoryblock of this zone.*/
>> + if (end_pfn == zone_end_pfn(zone))
>> 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)
>> + /*The mem block is the first memoryblock of ZONE_MOVABLE.*/
>
>> + if (start_pfn == zone->zone_start_pfn)
>> return sprintf(buf, "%s %s\n",
>> - zone->name, (zone - 1)->name);
>> + zone->name, (zone - 1)->name);
>
> How about swap zone->name and (zone - 1)->name.
>
> If swapping them, sample output of the sysfs files shows as follows:
> memory0/valid_zones: none
> memory1/valid_zones: DMA32
> memory2/valid_zones: DMA32
> memory3/valid_zones: DMA32
> memory4/valid_zones: Normal
> memory5/valid_zones: Normal
> memory6/valid_zones: Normal Movable
> memory7/valid_zones: Normal Movable
>
memory6/valid_zones: Normal Movable
memory7/valid_zones: Movable Normal
Here can better show the dividing line between ZONE_MOVABLE and ZONE_NORMAL.
The first column shows it's default zone,
for memory6:
the first column Normal shows that it can be onlined to ZONE_NORMAL by default.
echo offline > memory6/state
echo online > memory6/state
the second column Movable shows that it can be onlined to ZONE_MOVABLE by online_movable.
echo offline > memory6/state
echo online_movable > memory6/state
for memory7:
the first column Movable shows that it can be onlined to ZONE_MOVABLE by default.
echo offline > memory7/state
echo online > memory7/state
the second column Normal shows that it can be onlined to ZONE_NORMAL by online_kernel.
echo offline > memory7/state
echo online_kernel > memory7/state
And it is more convenient for script to work.
So i think we should leave it as it is.
Thanks!
~~~~~~~~~~~~~~
> memory8/valid_zones: Movable
>
> Thanks,
> Yasuaki Ishimatsu
>
>> }
>>
>> return sprintf(buf, "%s\n", zone->name);
>> }
>> -static DEVICE_ATTR(zones_online_to, 0444, show_zones_online_to, NULL);
>> +static DEVICE_ATTR(valid_zones, 0444, show_valid_zones, NULL);
>> #endif
>>
>> static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
>> @@ -587,7 +563,7 @@ static struct attribute *memory_memblk_attrs[] = {
>> &dev_attr_phys_device.attr,
>> &dev_attr_removable.attr,
>> #ifdef CONFIG_MEMORY_HOTREMOVE
>> - &dev_attr_zones_online_to.attr,
>> + &dev_attr_valid_zones.attr,
>> #endif
>> NULL
>> };
>>
>
>
>
> .
>
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