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

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

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.

This patchset includes couple fixes for problems I found while was working
on the shrinker, it also includes prerequisite DMA API usage improvement
needed by the shrinker.

The Mesa and IGT patches will be kept on hold until this kernel series
will be approved and applied.

This patchset was tested using Qemu and crosvm, including both cases of
IOMMU off/on.

Mesa: https://gitlab.freedesktop.org/digetx/mesa/-/commits/virgl-madvise
IGT:  https://gitlab.freedesktop.org/digetx/igt-gpu-tools/-/tree/virtio-madvise

Dmitry Osipenko (5):
  drm/virtio: Correct drm_gem_shmem_get_sg_table() error handling
  drm/virtio: Check whether transferred 2D BO is shmem
  drm/virtio: Unlock GEM reservations in error code path
  drm/virtio: Improve DMA API usage for shmem BOs
  drm/virtio: Add memory shrinker

 drivers/gpu/drm/virtio/Makefile               |   3 +-
 drivers/gpu/drm/virtio/virtgpu_drv.c          |  22 +++-
 drivers/gpu/drm/virtio/virtgpu_drv.h          |  31 ++++-
 drivers/gpu/drm/virtio/virtgpu_gem.c          |  84 ++++++++++++
 drivers/gpu/drm/virtio/virtgpu_gem_shrinker.c | 124 ++++++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_ioctl.c        |  37 ++++++
 drivers/gpu/drm/virtio/virtgpu_kms.c          |  17 ++-
 drivers/gpu/drm/virtio/virtgpu_object.c       |  63 +++------
 drivers/gpu/drm/virtio/virtgpu_plane.c        |  17 ++-
 drivers/gpu/drm/virtio/virtgpu_vq.c           |  30 +++--
 include/uapi/drm/virtgpu_drm.h                |  14 ++
 11 files changed, 373 insertions(+), 69 deletions(-)
 create mode 100644 drivers/gpu/drm/virtio/virtgpu_gem_shrinker.c

-- 
2.35.1