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Date:   Mon, 19 Apr 2021 14:16:51 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Peter Enderborg <peter.enderborg@sony.com>
Cc:     linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Muchun Song <songmuchun@bytedance.com>,
        Roman Gushchin <guro@fb.com>,
        Shakeel Butt <shakeelb@google.com>, NeilBrown <neilb@suse.de>,
        Sami Tolvanen <samitolvanen@google.com>,
        Mike Rapoport <rppt@kernel.org>, linux-media@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo
Message-ID: <YH10s/7MjxBBsjVL@dhcp22.suse.cz>
References: <20210417104032.5521-1-peter.enderborg@sony.com>
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On Sat 17-04-21 12:40:32, Peter Enderborg wrote:
> This adds a total used dma-buf memory. Details
> can be found in debugfs, however it is not for everyone
> and not always available. dma-buf are indirect allocated by
> userspace. So with this value we can monitor and detect
> userspace applications that have problems.

The changelog would benefit from more background on why this is needed,
and who is the primary consumer of that value.

I cannot really comment on the dma-buf internals but I have two remarks.
Documentation/filesystems/proc.rst needs an update with the counter
explanation and secondly is this information useful for OOM situations
analysis? If yes then show_mem should dump the value as well.

From the implementation point of view, is there any reason why this
hasn't used the existing global_node_page_state infrastructure?
-- 
Michal Hocko
SUSE Labs