Re: [PATCH v15 00/23] Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers

[Helen Mae Koike Fornazier]

On Sunday, August 27, 2023 14:54 -03, Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> wrote:

> This series:
> 
>   1. Adds common drm-shmem memory shrinker
>   2. Enables shrinker for VirtIO-GPU driver
>   3. Switches Panfrost driver to the common shrinker

Hi Dmitry, 

Would you mind testing with drm-ci? We virt-io tests there and it would be
really great to get your feedback of it.

https://cgit.freedesktop.org/drm/drm/log/?h=topic/drm-ci

You need to merge your changes with the above tree.
To configure it, you just need to have a tree on gitlab.freedesktop.org,
go to the settings and change the CI/CD configuration file from .gitlab-ci.yml
to drivers/gpu/drm/ci/gitlab-ci.yml, and you can start a pipeline
on your branch.

at the time of this writting, gitlab.freedesktop.org is under maintenance,
but it should be back soon.

Thank you!
Helen

> 
> Changelog:
> 
> v15:- Moved drm-shmem reference counters to use kref that allows to
>       optimize unlocked functions, like was suggested by Boris Brezillon.
> 
>     - Changed drm/gem/shmem function names to use _locked postfix and
>       dropped the _unlocked, making the naming scheme consistent across
>       DRM code, like was suggested by Boris Brezillon.
> 
>     - Added patch that fixes UAF in drm-shmem for drivers that import
>       dma-buf and then release buffer in the import error code path.
> 
>     - Added patch that makes drm-shmem use new flag for SGT's get_pages()
>       refcounting, preventing unbalanced refcounting when GEM is freed.
> 
>     - Fixed guest blob pinning in virtio-gpu driver that was missed
>       previously in the shrinker patch.
> 
>     - Moved VC4 and virtio-gpu drivers to use drm_gem_put() in
>       GEM-creation error code paths, which is now required by drm-shmem
>       and was missed in a previous patch versions.
> 
>     - Virtio-GPU now attaches shmem pages to host on first use and not
>       when BO is created. In older patch versions there was a potential
>       race condition in the BO creation code path where both
>       get_sgt()+object_attach() should've been made under same resv lock,
>       otherwise pages could be evicted before attachment is invoked.
> 
>     - Virtio-GPU and drm-shmem shrinker patches are split into smaller
>       ones.
> 
> v14:- All the prerequisite reservation locking patches landed upstream,
>       previously were a part of this series in v13 and older.
> 
>         https://lore.kernel.org/dri-devel/20230529223935.2672495-1-dmitry.osipenko@xxxxxxxxxxxxx/
> 
>     - Added patches to improve locked/unlocked function names, like was
>       suggested by Boris Brezillon for v13.
> 
>     - Made all exported drm-shmem symbols GPL, like was previously
>       discussed with Thomas Zimmermann on this series.
> 
>     - Improved virtio-gpu shrinker patch. Now it won't detach purged BO
>       when userspace closes GEM. Crosvm (and not qemu) checks res_id on
>       CMD_CTX_DETACH_RESOURCE and prints noisy error message if ID is
>       invalid, which wasn't noticed before.
> 
> v13:- Updated virtio-gpu shrinker patch to use drm_gem_shmem_object_pin()
>       directly instead of drm_gem_pin() and dropped patch that exported
>       drm_gem_pin() functions, like was requested by Thomas Zimmermann in
>       v12.
> 
> v12:- Fixed the "no previous prototype for function" warning reported by
>       kernel build bot for v11.
> 
>     - Fixed the missing reservation lock reported by Intel CI for VGEM
>       driver. Other drivers using drm-shmem were affected similarly to
>       VGEM. The problem was in the dma-buf attachment code path that led
>       to drm-shmem pinning function which assumed the held reservation lock
>       by drm_gem_pin(). In the past that code path was causing trouble for
>       i915 driver and we've changed the locking scheme for the attachment
>       code path in the dma-buf core to let exporters to handle the locking
>       themselves. After a closer investigation, I realized that my assumption
>       about testing of dma-buf export code path using Panfrost driver was
>       incorrect. Now I created additional local test to exrecise the Panfrost
>       export path. I also reproduced the issue reported by the Intel CI for
>       v10. It's all fixed now by making the drm_gem_shmem_pin() to take the
>       resv lock by itself.
> 
>     - Patches are based on top of drm-tip, CC'd intel-gfx CI for testing.
> 
> v11:- Rebased on a recent linux-next. Added new patch as a result:
> 
>         drm/shmem-helper: Export drm_gem_shmem_get_pages_sgt_locked()
> 
>         It's needed by the virtio-gpu driver to swap-in/unevict shmem
>         object, previously get_pages_sgt() didn't use locking.
> 
>     - Separated the "Add memory shrinker" patch into smaller parts to ease
>       the reviewing, as was requested by Thomas Zimmermann:
> 
>         drm/shmem-helper: Factor out pages alloc/release from
>           drm_gem_shmem_get/put_pages()
>         drm/shmem-helper: Add pages_pin_count field
>         drm/shmem-helper: Switch drm_gem_shmem_vmap/vunmap to use pin/unpin
>         drm/shmem-helper: Factor out unpinning part from drm_gem_shmem_purge()
> 
>     - Addessed the v10 review comments from Thomas Zimmermann: return errno
>       instead of bool, sort code alphabetically, rename function and etc
>       minor changes.
> 
>     - Added new patch to remove the "map->is_iomem" from drm-shmem, as
>       was suggested by Thomas Zimmermann.
> 
>     - Added acks and r-b's that were given to v10.
> 
> v10:- Was partially applied to misc-fixes/next.
> 
>       https://lore.kernel.org/dri-devel/6c16f303-81df-7ebe-85e9-51bb40a8b301@xxxxxxxxxxxxx/T/
> 
> Dmitry Osipenko (23):
>   drm/shmem-helper: Fix UAF in error path when freeing SGT of imported
>     GEM
>   drm/shmem-helper: Use flag for tracking page count bumped by
>     get_pages_sgt()
>   drm/gem: Change locked/unlocked postfix of drm_gem_v/unmap() function
>     names
>   drm/gem: Add _locked postfix to functions that have unlocked
>     counterpart
>   drm/v3d: Replace open-coded drm_gem_shmem_free() with
>     drm_gem_object_put()
>   drm/virtio: Replace drm_gem_shmem_free() with drm_gem_object_put()
>   drm/shmem-helper: Make all exported symbols GPL
>   drm/shmem-helper: Refactor locked/unlocked functions
>   drm/shmem-helper: Remove obsoleted is_iomem test
>   locking/refcount, kref: Add kref_put_ww_mutex()
>   dma-resv: Add kref_put_dma_resv()
>   drm/shmem-helper: Add and use pages_pin_count
>   drm/shmem-helper: Use kref for pages_use_count
>   drm/shmem-helper: Add and use lockless drm_gem_shmem_get_pages()
>   drm/shmem-helper: Switch drm_gem_shmem_vmap/vunmap to use pin/unpin
>   drm/shmem-helper: Use kref for vmap_use_count
>   drm/shmem-helper: Add and use drm_gem_shmem_resv_assert_held() helper
>   drm/shmem-helper: Add memory shrinker
>   drm/shmem-helper: Export drm_gem_shmem_get_pages_sgt_locked()
>   drm/virtio: Pin display framebuffer BO
>   drm/virtio: Attach shmem BOs dynamically
>   drm/virtio: Support memory shrinking
>   drm/panfrost: Switch to generic memory shrinker
> 
>  drivers/gpu/drm/drm_client.c                  |   6 +-
>  drivers/gpu/drm/drm_gem.c                     |  26 +-
>  drivers/gpu/drm/drm_gem_framebuffer_helper.c  |   6 +-
>  drivers/gpu/drm/drm_gem_shmem_helper.c        | 616 +++++++++++++++---
>  drivers/gpu/drm/drm_internal.h                |   4 +-
>  drivers/gpu/drm/drm_prime.c                   |   4 +-
>  drivers/gpu/drm/lima/lima_gem.c               |  11 +-
>  drivers/gpu/drm/lima/lima_sched.c             |   4 +-
>  drivers/gpu/drm/panfrost/Makefile             |   1 -
>  drivers/gpu/drm/panfrost/panfrost_device.h    |   4 -
>  drivers/gpu/drm/panfrost/panfrost_drv.c       |  29 +-
>  drivers/gpu/drm/panfrost/panfrost_dump.c      |   4 +-
>  drivers/gpu/drm/panfrost/panfrost_gem.c       |  36 +-
>  drivers/gpu/drm/panfrost/panfrost_gem.h       |   9 -
>  .../gpu/drm/panfrost/panfrost_gem_shrinker.c  | 122 ----
>  drivers/gpu/drm/panfrost/panfrost_job.c       |  18 +-
>  drivers/gpu/drm/panfrost/panfrost_mmu.c       |   4 +-
>  drivers/gpu/drm/panfrost/panfrost_perfcnt.c   |   6 +-
>  drivers/gpu/drm/v3d/v3d_bo.c                  |  26 +-
>  drivers/gpu/drm/virtio/virtgpu_drv.h          |  22 +-
>  drivers/gpu/drm/virtio/virtgpu_gem.c          |  80 +++
>  drivers/gpu/drm/virtio/virtgpu_ioctl.c        |  57 +-
>  drivers/gpu/drm/virtio/virtgpu_kms.c          |   8 +
>  drivers/gpu/drm/virtio/virtgpu_object.c       | 147 ++++-
>  drivers/gpu/drm/virtio/virtgpu_plane.c        |  17 +-
>  drivers/gpu/drm/virtio/virtgpu_submit.c       |  15 +-
>  drivers/gpu/drm/virtio/virtgpu_vq.c           |  40 ++
>  include/drm/drm_device.h                      |  10 +-
>  include/drm/drm_gem.h                         |   6 +-
>  include/drm/drm_gem_shmem_helper.h            | 141 +++-
>  include/linux/dma-resv.h                      |   9 +
>  include/linux/kref.h                          |  12 +
>  include/linux/refcount.h                      |   5 +
>  include/uapi/drm/virtgpu_drm.h                |  14 +
>  lib/refcount.c                                |  34 +
>  35 files changed, 1167 insertions(+), 386 deletions(-)
>  delete mode 100644 drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> 
> -- 
> 2.41.0
>