Add support for the newly added kernel memory auto onlining policy to Xen
ballon driver.
Suggested-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/xen/Kconfig | 20 +++++++++++++-------
drivers/xen/balloon.c | 30 +++++++++++++++++++-----------
2 files changed, 32 insertions(+), 18 deletions(-)
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 73708ac..098ab49 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -37,23 +37,29 @@ config XEN_BALLOON_MEMORY_HOTPLUG
Memory could be hotplugged in following steps:
- 1) dom0: xl mem-max <domU> <maxmem>
+ 1) domU: ensure that memory auto online policy is in effect by
+ checking /sys/devices/system/memory/auto_online_blocks file
+ (should be 'online').
+
+ 2) dom0: xl mem-max <domU> <maxmem>
where <maxmem> is >= requested memory size,
- 2) dom0: xl mem-set <domU> <memory>
+ 3) dom0: xl mem-set <domU> <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,
- 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 domU 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
- SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
+ or by adding the following line to udev rules:
- In that case step 3 should be omitted.
+ SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
int "Hotplugged memory limit (in GiB) for a PV guest"
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 890c3b5..68f0aa2 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -284,7 +284,7 @@ static void release_memory_resource(struct resource *resource)
kfree(resource);
}
-static enum bp_state reserve_additional_memory(void)
+static enum bp_state reserve_additional_memory(bool online)
{
long credit;
struct resource *resource;
@@ -338,7 +338,18 @@ 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. It is safe because there can only be
+ * one balloon_process() running at a time and balloon_mutex is
+ * internal to Xen driver, generic memory hotplug code doesn't mess
+ * with it.
+ */
+ mutex_unlock(&balloon_mutex);
+ rc = add_memory_resource(nid, resource, online);
+ mutex_lock(&balloon_mutex);
+
if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
goto err;
@@ -562,14 +573,11 @@ static void balloon_process(struct work_struct *work)
credit = current_credit();
- if (credit > 0) {
- if (balloon_is_inflated())
- state = increase_reservation(credit);
- else
- state = reserve_additional_memory();
- }
-
- if (credit < 0)
+ if (credit > 0 && balloon_is_inflated())
+ state = increase_reservation(credit);
+ else if (credit > 0)
+ state = reserve_additional_memory(memhp_auto_online);
+ else if (credit < 0)
state = decrease_reservation(-credit, GFP_BALLOON);
state = update_schedule(state);
@@ -599,7 +607,7 @@ static int add_ballooned_pages(int nr_pages)
enum bp_state st;
if (xen_hotplug_unpopulated) {
- st = reserve_additional_memory();
+ st = reserve_additional_memory(false);
if (st != BP_ECANCELED) {
mutex_unlock(&balloon_mutex);
wait_event(balloon_wq,
--
2.5.0
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