Re: [PATCH] memory-hotplug: fix not enough check of valid_zones

[Zhang Zhen <zhenzhang.zhang@huawei.com>]

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@huawei.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@huawei.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
>>   };
>>
> 
> 
> 
> .
> 


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>