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memory-hotplug: add automatic onlining policy for the newly added memory

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Currently, all newly added memory blocks remain in 'offline' state
unless someone onlines them, some linux distributions carry special udev
rules like:

  SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"

to make this happen automatically.  This is not a great solution for
virtual machines where memory hotplug is being used to address high
memory pressure situations as such onlining is slow and a userspace
process doing this (udev) has a chance of being killed by the OOM killer
as it will probably require to allocate some memory.

Introduce default policy for the newly added memory blocks in
/sys/devices/system/memory/auto_online_blocks file with two possible
values: "offline" which preserves the current behavior and "online"
which causes all newly added memory blocks to go online as soon as
they're added.  The default is "offline".

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vitaly Kuznetsov
2016-03-15 14:56:48 -07:00
committed by Linus Torvalds
parent 9cb65bc3b1
commit 31bc3858ea
6 changed files with 75 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
drivers/base/memory.c
View File

@@ -251,7 +251,7 @@ memory_block_action(unsigned long phys_index, unsigned long action, int online_t
return ret;
}
static int memory_block_change_state(struct memory_block *mem,
int memory_block_change_state(struct memory_block *mem,
unsigned long to_state, unsigned long from_state_req)
{
int ret = 0;
@@ -438,6 +438,37 @@ print_block_size(struct device *dev, struct device_attribute *attr,
static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
/*
* Memory auto online policy.
*/
static ssize_t
show_auto_online_blocks(struct device *dev, struct device_attribute *attr,
char *buf)
{
if (memhp_auto_online)
return sprintf(buf, "online\n");
else
return sprintf(buf, "offline\n");
}
static ssize_t
store_auto_online_blocks(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
if (sysfs_streq(buf, "online"))
memhp_auto_online = true;
else if (sysfs_streq(buf, "offline"))
memhp_auto_online = false;
else
return -EINVAL;
return count;
}
static DEVICE_ATTR(auto_online_blocks, 0644, show_auto_online_blocks,
store_auto_online_blocks);
/*
* Some architectures will have custom drivers to do this, and
* will not need to do it from userspace. The fake hot-add code
@@ -746,6 +777,7 @@ static struct attribute *memory_root_attrs[] = {
#endif
&dev_attr_block_size_bytes.attr,
&dev_attr_auto_online_blocks.attr,
NULL
};