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

[Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>]

(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.

> 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
                              ~~~~~~~~~~~~~~
  	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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