linux-kernel - Re: [PATCH 5/4] update ksm userspace interfaces

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Message-ID: <49D5E9B5.1020101@redhat.com>
Date:	Fri, 03 Apr 2009 13:49:25 +0300
From:	Izik Eidus <ieidus@...hat.com>
To:	Gerd Hoffmann <kraxel@...hat.com>
CC:	Chris Wright <chrisw@...hat.com>,
	Anthony Liguori <anthony@...emonkey.ws>,
	Andrea Arcangeli <aarcange@...hat.com>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	linux-mm@...ck.org, avi@...hat.com, riel@...hat.com,
	jeremy@...p.org, mtosatti@...hat.com, hugh@...itas.com,
	corbet@....net, yaniv@...hat.com, dmonakhov@...nvz.org
Subject: Re: [PATCH 5/4] update ksm userspace interfaces

Gerd Hoffmann wrote:
> Izik Eidus wrote:
>   
>> The main problem that ksm will face when removing the fd interface is:
>> right now when you register memory into ksm, you open fd, and then ksm
>> do get_task_mm(), we will do mmput when the file will be closed
>>     
>
> Did you test whenever it really cleans up in case you "kill -9 qemu"?
>
> I recently did something simliar with the result that the extra
> reference hold on mm_struct prevented the process memory from being
> zapped ...
>
> cheers,
>   Gerd
>   
Did you use mmput() after you called get_task_mm() ???
get_task_mm() do nothing beside atomic_inc(&mm->mm_users);

and mmput() do nothing beside dec this counter and check if no reference 
are available to this....

Am i missing anything?
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