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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>
hifive-unleashed-5.1
Vitaly Kuznetsov 2015-03-18 12:29:22 -07:00 committed by Greg Kroah-Hartman
parent fde25d25db
commit f3f6eb8087
1 changed files with 1 additions and 0 deletions
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drivers/hv/hv_balloon.c
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@ -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;
}