linux-kernel - Re: [PATCH v10 00/11] Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers

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Message-ID: <c6ae4f5f-7fe1-5497-a611-bee57672c289@collabora.com>
Date:   Thu, 16 Feb 2023 23:43:38 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Gerd Hoffmann <kraxel@...hat.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, virtualization@...ts.linux-foundation.org,
        David Airlie <airlied@...il.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Chia-I Wu <olvaffe@...il.com>,
        Daniel Almeida <daniel.almeida@...labora.com>,
        Gustavo Padovan <gustavo.padovan@...labora.com>,
        Daniel Stone <daniel@...ishbar.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Rob Clark <robdclark@...il.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        Qiang Yu <yuq825@...il.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        Rob Herring <robh@...nel.org>, Sean Paul <sean@...rly.run>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>
Subject: Re: [PATCH v10 00/11] Add generic memory shrinker to VirtIO-GPU and
 Panfrost DRM drivers

On 2/16/23 15:15, Daniel Vetter wrote:
> On Mon, Jan 30, 2023 at 03:02:10PM +0300, Dmitry Osipenko wrote:
>> On 1/27/23 11:13, Gerd Hoffmann wrote:
>>> On Thu, Jan 26, 2023 at 01:55:09AM +0300, Dmitry Osipenko wrote:
>>>> Hello Thomas and Gerd,
>>>>
>>>> On 1/9/23 00:04, Dmitry Osipenko wrote:
>>>>> This series:
>>>>>
>>>>>   1. Makes minor fixes for drm_gem_lru and Panfrost
>>>>>   2. Brings refactoring for older code
>>>>>   3. Adds common drm-shmem memory shrinker
>>>>>   4. Enables shrinker for VirtIO-GPU driver
>>>>>   5. Switches Panfrost driver to the common shrinker
>>>>>
>>>>> Changelog:
>>>>>
>>>>> v10:- Rebased on a recent linux-next.
>>>>>
>>>>>     - Added Rob's ack to MSM "Prevent blocking within shrinker loop" patch.
>>>>>
>>>>>     - Added Steven's ack/r-b/t-b for the Panfrost patches.
>>>>>
>>>>>     - Fixed missing export of the new drm_gem_object_evict() function.
>>>>>
>>>>>     - Added fixes tags to the first two patches that are making minor fixes,
>>>>>       for consistency.
>>>>
>>>> Do you have comments on this version? Otherwise ack will be appreciated.
>>>> Thanks in advance!
>>>
>>> Don't feel like signing off on the locking changes, I'm not that
>>> familiar with the drm locking rules.  So someone else looking at them
>>> would be good.  Otherwise the series and specifically the virtio changes
>>> look good to me.
>>>
>>> Acked-by: Gerd Hoffmann <kraxel@...hat.com>
>>
>> Thomas was looking at the the DRM core changes. I expect he'll ack them.
>>
>> Thank you for reviewing the virtio patches!
> 
> I think best-case would be an ack from msm people that this looks good
> (even better a conversion for msm to start using this).

The MSM pretty much isn't touched by this patchset, apart from the minor
common shrinker fix. Moving whole MSM to use drm_shmem should be a big
change to the driver.

The Panfrost and VirtIO-GPU drivers already got the acks. I also tested
the Lima driver, which uses drm-shmem helpers. Other DRM drivers should
be unaffected by this series.

> Otherwise I think the locking looks reasonable, I think the tricky bits
> have been moving the dma-buf rules, but if you want I can try to take
> another in-depth look. But would need to be in 2 weeks since I'm going on
> vacations, pls ping me on irc if I'm needed.

The locking conversion is mostly a straightforward replacement of mutex
with resv lock for drm-shmem. The dma-buf rules were tricky, another
tricky part was fixing the lockdep warning for the bogus report of
fs_reclaim vs GEM shrinker at the GEM destroy time where I borrowed the
drm_gem_shmem_resv_assert_held() solution from the MSM driver where Rob
had a similar issue.

> Otherwise would be great if we can land this soon, so that it can soak the
> entire linux-next cycle to catch any driver specific issues.

That will be great. Was waiting for Thomas to ack the shmem patches
since he reviewed the previous versions, but if you or anyone else could
ack them, then will be good too. Thanks!

-- 
Best regards,
Dmitry