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xen_balloon: support memory auto onlining policy

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Add support for the newly added kernel memory auto onlining policy to
Xen ballon driver.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Acked-by: David Vrabel <david.vrabel@citrix.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 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 14:56:52 -07:00 committed by Linus Torvalds
parent 31bc3858ea
commit 703fc13a3f
2 changed files with 25 additions and 9 deletions
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23
drivers/xen/Kconfig
View File

@ -37,24 +37,31 @@ config XEN_BALLOON_MEMORY_HOTPLUG
Memory could be hotplugged in following steps:
1) dom0: xl mem-max <domU> <maxmem>
1) target domain: ensure that memory auto online policy is in
effect by checking /sys/devices/system/memory/auto_online_blocks
file (should be 'online').
2) control domain: xl mem-max <target-domain> <maxmem>
where <maxmem> is >= requested memory size,
2) dom0: xl mem-set <domU> <memory>
3) control domain: xl mem-set <target-domain> <memory>
where <memory> is requested memory size; alternatively memory
could be added by writing proper value to
/sys/devices/system/xen_memory/xen_memory0/target or
/sys/devices/system/xen_memory/xen_memory0/target_kb on dumU,
/sys/devices/system/xen_memory/xen_memory0/target_kb on the
target domain.
3) domU: for i in /sys/devices/system/memory/memory*/state; do \
[ "`cat "$i"`" = offline ] && echo online > "$i"; done
Alternatively, if memory auto onlining was not requested at step 1
the newly added memory can be manually onlined in the target domain
by doing the following:
Memory could be onlined automatically on domU by adding following line to udev rules:
for i in /sys/devices/system/memory/memory*/state; do \
[ "`cat "$i"`" = offline ] && echo online > "$i"; done
or by adding the following line to udev rules:
SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
In that case step 3 should be omitted.
config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
int "Hotplugged memory limit (in GiB) for a PV guest"
default 512 if X86_64

11
drivers/xen/balloon.c
View File

@ -338,7 +338,16 @@ static enum bp_state reserve_additional_memory(void)
}
#endif
rc = add_memory_resource(nid, resource, false);
/*
* add_memory_resource() will call online_pages() which in its turn
* will call xen_online_page() callback causing deadlock if we don't
* release balloon_mutex here. Unlocking here is safe because the
* callers drop the mutex before trying again.
*/
mutex_unlock(&balloon_mutex);
rc = add_memory_resource(nid, resource, memhp_auto_online);
mutex_lock(&balloon_mutex);
if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
goto err;