> -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > Sent: Monday, March 2, 2015 2:34 AM > To: KY Srinivasan > Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; Haiyang Zhang; linux- > kernel@xxxxxxxxxxxxxxx; Dexuan Cui > Subject: Re: [PATCH] Drivers: hv: hv_balloon: keep locks balanced on > add_memory() failure > > Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes: > > > 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. > > > > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > > --- > > This patch is dependent on the previously posted 'Drivers: hv: hv_balloon: > > eliminate the trylock path in acquire/release_region_mutex'. > > Hi K.Y., > > I don't see this patch in your '[PATCH 0/7] Drivers: hv: Collection fixes and > enhancements' sent to Greg. Please let me know if you see any issues with it > as it looks like a pretty important bugfix to me. Yes, I am sending this patch out soon. K. Y > > Thanks, > > > --- > > drivers/hv/hv_balloon.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index > > 1283035..771bf84 100644 > > --- a/drivers/hv/hv_balloon.c > > +++ b/drivers/hv/hv_balloon.c > > @@ -654,6 +654,7 @@ 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; > > } > > -- > Vitaly _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
