Drivers: hv: hv_balloon: keep locks balanced on add_memory() failure
When add_memory() fails the following BUG is observed:
[ 743.646107] hv_balloon: hot_add memory failed error is -17
[ 743.679973]
[ 743.680930] =====================================
[ 743.680930] [ BUG: bad unlock balance detected! ]
[ 743.680930] 3.19.0-rc5_bug1131426+ #552 Not tainted
[ 743.680930] -------------------------------------
[ 743.680930] kworker/0:2/255 is trying to release lock (&dm_device.ha_region_mutex) at:
[ 743.680930] [<ffffffff81aae5fe>] mutex_unlock+0xe/0x10
[ 743.680930] but there are no more locks to release!
This happens as we don't acquire ha_region_mutex and hot_add_req() expects us
to as it does unconditional mutex_unlock(). Acquire the lock on the error path.
The current char-next branch is broken and this patch fixes
the bug.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index c5bb872..f1f17c5 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -652,6 +652,7 @@
}
has->ha_end_pfn -= HA_CHUNK;
has->covered_end_pfn -= processed_pfn;
+ mutex_lock(&dm_device.ha_region_mutex);
break;
}