[PATCH 4.4 11/59] xen/balloon: fix ballooned page accounting without hotplug enabled

From: Greg Kroah-Hartman
Date: Sat Jan 11 2020 - 04:50:54 EST


From: Juergen Gross <jgross@xxxxxxxx>

[ Upstream commit c673ec61ade89bf2f417960f986bc25671762efb ]

When CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is not defined
reserve_additional_memory() will set balloon_stats.target_pages to a
wrong value in case there are still some ballooned pages allocated via
alloc_xenballooned_pages().

This will result in balloon_process() no longer be triggered when
ballooned pages are freed in batches.

Reported-by: Nicholas Tsirakis <niko.tsirakis@xxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/xen/balloon.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index cfab1d24e4bc..1c789056e7e8 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -392,7 +392,8 @@ static struct notifier_block xen_memory_nb = {
#else
static enum bp_state reserve_additional_memory(void)
{
- balloon_stats.target_pages = balloon_stats.current_pages;
+ balloon_stats.target_pages = balloon_stats.current_pages +
+ balloon_stats.target_unpopulated;
return BP_ECANCELED;
}
#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
--
2.20.1