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Date: Thu, 5 Jul 2018 07:56:54 +0200
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Subject: Re: [Qemu-devel] [PATCH] exec.c: check RAMBlock validity before
 changing its flag
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To: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>
Cc: qemu-devel@nongnu.org, "Dr . David Alan Gilbert" <dgilbert@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, "Michael S. Tsirkin" <mst@redhat.com>, Alex Williamson <alex.williamson@redhat.com>, David Gibson <david@gibson.dropbear.id.au>

Hello Paolo,

On 07/04/2018 02:16 PM, Paolo Bonzini wrote:
> On 04/07/2018 11:55, Peter Xu wrote:
>>>     commit b0e56e0b63f350691b52d3e75e89bb64143fbeff
>>>     Author: Hu Tao <hutao@cn.fujitsu.com>
>>>     Date:   Wed Apr 2 15:13:27 2014 +0800
>>>
>>>     unset RAMBlock idstr when unregister MemoryRegion
>>>
>>>     Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
>>>     Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>>
>>> whose commit message is a bit lacking, but
>>> http://lists.gnu.org/archive/html/qemu-devel/2014-04/msg00282.html helps
>>> more.  It seems like the original bug was a reference count issue.
>>>
>>> Clearing the new migratable flag should also be unnecessary.
>> But even if we get rid of vmstate_unregister_ram(), the leak could
>> still be there?
>>
>> I'm not sure what was leaked when b0e56e0b6 was introduced, I feel
>> like it's the RAMBlock of the memdev.  Here I think the ROM memory
>> region seems to be leaked as well (along with the RAMBlock inside)?
> 
> The leak would be another bug that vmstate_unregister_ram is just
> papering over.  We need to test memory unplug with
> vmstate_unregister_ram removed, and fix bugs if any.

So for the time being, you would just get rid of pci_del_option_rom()
which only does vmstate_unregister_ram() ? 

Thanks,

C.