Hello Mike,

Am 15.08.19 um 19:57 schrieb Mike Christie:
>> Don't waste your time. I found a way to replicate it now.
> Just a quick update.
> Looks like we are trying to allocate memory in the IO path in a way that
> can swing back on us, so we can end up locking up. You are probably not
> hitting this with krbd in your setup because normally it's preallocating
> structs, using flags like GFP_NOIO, etc. For rbd-nbd, we cannot
> preallocate some structs and cannot control the allocation flags for
> some operations initiated from userspace, so its possible to hit this
> every IO. I can replicate this now in a second just doing a cp -r.
> It's not going to be a simple fix. We have had a similar issue for
> storage daemons like iscsid and multipathd since they were created. It's
> less likey to hit with them because you only hit the paths they cannot
> control memory allocation behavior during recovery.
> I am looking into some things now.

Great to hear, that the problem is now identified.

As described I'm on vacation -  if you need anything after the 8.9. we can 
probably invest some time to test upcoming fixes.


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