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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2007-08-13 16:10:44


On Aug 13, 2007, at 4:04 PM, Gleb Natapov wrote:

>> mpool rdma finalize was empty function. I changed it to do the
>> "finalize" job - go over all registered segments in mpool and
>> release
>> them one by one,
>> Mpool use reference counter for each memory region and it prevents us
>> from double free bug. In openib btl all memory that was registered
>> with
>> mpool on finalize stage will be unregistered with mpool too.
>> So maybe in gm the memory (that was registred with mpool) released
>> directly (not via mpool) and it cause the segfault.
>>
> As far as I understand the problem Tim see is much more serious.
> During
> finalize gm BTL is unloaded and only after that mpool finalize is
> called. Mpool uses callbacks into gm BTL to register/unregister
> memory,
> but BTL is not there already.

Right. We had the same problem in the openib btl, too. See https://
svn.open-mpi.org/trac/ompi/changeset/15735.

I don't know if this is the exact same scenario Tim is running into,
but the end result is the same (openib btl was being destroyed and
still leaving memory registered in the mpool).

-- 
Jeff Squyres
Cisco Systems