linux-kernel - Re: [PATCH v1 0/5] Add memory shrinker to VirtIO-GPU DRM driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c9b344ab-b674-d600-da13-94b329a9d46b@collabora.com>
Date:   Thu, 10 Mar 2022 01:25:43 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Chia-I Wu <olvaffe@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Daniel Almeida <daniel.almeida@...labora.com>,
        Gert Wollny <gert.wollny@...labora.com>
Cc:     Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Gustavo Padovan <gustavo.padovan@...labora.com>,
        dri-devel@...ts.freedesktop.org, Dmitry Osipenko <digetx@...il.com>
Subject: Re: [PATCH v1 0/5] Add memory shrinker to VirtIO-GPU DRM driver

On 3/9/22 22:28, Thomas Zimmermann wrote:
> Hi
> 
> Am 09.03.22 um 12:55 schrieb Dmitry Osipenko:
>> Hello,
>>
>> On 3/9/22 11:59, Thomas Zimmermann wrote:
>>> Hi
>>>
>>> Am 08.03.22 um 14:17 schrieb Dmitry Osipenko:
>>>> Hello,
>>>>
>>>> This patchset introduces memory shrinker for the VirtIO-GPU DRM driver.
>>>> During OOM, the shrinker will release BOs that are marked as "not
>>>> needed"
>>>> by userspace using the new madvise IOCTL. The userspace in this case is
>>>> the Mesa VirGL driver, it will mark the cached BOs as "not needed",
>>>> allowing kernel driver to release memory of the cached shmem BOs on
>>>> lowmem
>>>> situations, preventing OOM kills.
>>>
>>> Virtio-gpu is build on top of GEM shmem helpers. I have a prototype
>>> patchset that adds a shrinker to these helpers. If you want to go
>>> further, you could implement something like that instead. Panfrost and
>>> lima also have their own shrinker and could certainly be converted to
>>> the gem-shmem shrinker.
>>
>> I had a thought that it could be possible to unify shrinkers into a
>> common DRM framework. Could you please give me a link to yours prototype
>> patchset?
> 
> I uploaded the patches to
> 
> 
> https://gitlab.freedesktop.org/tzimmermann/linux/-/commits/gem-shmem-cached-mappings
> 
> 
> it's incomplete and un-debugged, but it shows what needs to be done. It
> has the infrastructure, but lacks the changes to the GEM shmem code.
> 
> The reason for this work is to keep GEM shmem pages mapped and allocated
> even while the BO is neither mapped nor pinned.  As it is now, GEM SHMEM
> creates and releases pages on each pin and unpin, and maps and unmaps
> memory ranges on each vmap and vunmap.  It's all wasteful. Only the
> first pin and vmap calls should establish pages and mappings and only
> the purge and free functions should release them.

Hm, aren't maps and pins already refcounted?

> The patchset adds new helpers for BO purging to struct
> drm_gem_object_funcs. With this, I think it might be possible to have
> one global DRM shrinker and let it handle all BOs; independent of each
> BO's memory manager.

Thank you, I'll give it a try.