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Message-ID: <53FC6009.1010308@jp.fujitsu.com>
Date: Tue, 26 Aug 2014 19:23:05 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To: Zhang Zhen <zhenzhang.zhang@...wei.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Dave Hansen <dave.hansen@...el.com>,
Toshi Kani <toshi.kani@...com>,
David Rientjes <rientjes@...gle.com>
CC: <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
(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@...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
~~~~~~~~~~~~~~
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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