Commit f3f6eb80 authored Mar 18, 2015 by Vitaly Kuznetsov Committed by Greg Kroah-Hartman Mar 25, 2015

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>

parent fde25d25

drivers/hv/hv_balloon.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -652,6 +652,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
		}
		has->ha_end_pfn -= HA_CHUNK;
		has->covered_end_pfn -= processed_pfn;
		mutex_lock(&dm_device.ha_region_mutex);
		break;
		}

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