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Commit 703fc13a authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Linus Torvalds
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xen_balloon: support memory auto onlining policy 



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

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Suggested-by: default avatarDaniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: default avatarDaniel Kiper <daniel.kiper@oracle.com>
Acked-by: default avatarDavid 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 31bc3858

drivers/xen/Kconfig

+15 −8
Original line number Diff line number Diff line
@@ -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.



	  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:



	    3) domU: for i in /sys/devices/system/memory/memory*/state; do \

		for i in /sys/devices/system/memory/memory*/state; do \

		  [ "`cat "$i"`" = offline ] && echo online > "$i"; done



	  Memory could be onlined automatically on domU by adding following line to udev rules:

	  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

drivers/xen/balloon.c

+10 −1
Original line number Diff line number Diff line
@@ -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;