[PATCH 0/3] drm/gem-shmem: Track page accessed/dirty status

[Thomas Zimmermann <tzimmermann@suse.de>]

Track page access/dirty status in gem-shmem for better integration with
the overall memory management. Gem-shmem has long had two flags bits in
struct drm_gem_shmem_object, named pages_mark_accessed_on_put and
pages_mark_dirty_on_put, but never used them much; except for some odd
cases in drivers. Therefore pages in gem-shmem where never marked
correctly. (Other DRM memory managers do some course-grain tracking at
least).

Patch 1 switches from PFN-based mapping to page mapping. The pages are
already available; only the mmap handling needs to be adapted.

Patch 2 adds tracking access and dirty status in mmap.

Patch 3 adds tracking access and dirty status in vmap. Becasue there's
no fault handling here, we refer to the existing status bits in struct
drm_gem_shmem_object. Each page's status will be updated by the page
release in drm_gem_put_pages(). The imagiantion driver requires a small
fix to make it work correctly.

Tested with CONFIG_VM=y by running animations on DRM's bochs driver for
several hours. This uses gem-shmem's mmap and vmap extensively.

Thomas Zimmermann (3):
  drm/gem-shmem: Map pages in mmap fault handler
  drm/gem-shmem: Track folio accessed/dirty status in mmap
  drm/gem-shmem: Track folio accessed/dirty status in vmap

 drivers/gpu/drm/drm_gem_shmem_helper.c | 78 ++++++++++++++++++--------
 drivers/gpu/drm/imagination/pvr_gem.c  |  6 +-
 2 files changed, 59 insertions(+), 25 deletions(-)

-- 
2.52.0