Subject: Re: [RFC 0/6] Module for tracking/accounting shared memory buffers
To: Ruchi Kandoi <kandoiruchi@google.com>, <gregkh@linuxfoundation.org>,
        <arve@android.com>, <riandrews@android.com>, <sumit.semwal@linaro.org>,
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References: <1476229810-26570-1-git-send-email-kandoiruchi@google.com>
From: =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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Date: Wed, 12 Oct 2016 11:09:47 +0200
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Am 12.10.2016 um 01:50 schrieb Ruchi Kandoi:
> This patchstack adds memtrack hooks into dma-buf and ion.  If there's upstream
> interest in memtrack, it can be extended to other memory allocators as well,
> such as GEM implementations.
We have run into similar problems before. Because of this I already 
proposed a solution for this quite a while ago, but never pushed on 
upstreaming this since it was only done for a special use case.

Instead of keeping track of how much memory a process has bound (which 
is very fragile) my solution  only added some more debugging info on a 
per fd basis (e.g. how much memory is bound to this fd).

This information was then used by the OOM killer (for example) to make a 
better decision on which process to reap.

Shouldn't be to hard to expose this through debugfs or maybe a new fcntl 
to userspace for debugging.

I haven't looked at the code in detail, but messing with the per process 
memory accounting like you did in this proposal is clearly not a good 
idea if you ask me.

Regards,
Christian.