'Drivers: hv: hv_balloon: refuse to balloon below the floor' fix does not
correctly handle the case when val.freeram < num_pages as val.freeram is
__kernel_ulong_t and the 'val.freeram - num_pages' value will be a huge
positive value instead of being negative.
Usually host doesn't ask us to balloon more than val.freeram but in case
he have a memory hog started after we post the last pressure report we
can get into troubles.
Suggested-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/hv/hv_balloon.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index d8c5802..20bfe36 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -1145,7 +1145,7 @@ static void balloon_up(struct work_struct *dummy)
floor = compute_balloon_floor();
/* Refuse to balloon below the floor, keep the 2M granularity. */
- if (val.freeram - num_pages < floor) {
+ if (val.freeram < num_pages || val.freeram - num_pages < floor) {
num_pages = val.freeram > floor ? (val.freeram - floor) : 0;
num_pages -= num_pages % PAGES_IN_2M;
}
--
1.9.3
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