[PATCH v2 0/4] 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 flag 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).

Patches 1 and 2 switch from PFN-based mapping to page mapping. The pages
are already available; only the mmap handling needs to be adapted.

Patch 3 adds tracking access and dirty status in mmap.

Patch 4 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 imagination 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.

v2:
- fix possible OOB access into page array (Matthew)
- simplify fault-handler error handling (Boris)
- simplify internal interfaces (Matthew)

Thomas Zimmermann (4):
  drm/gem-shmem: Return vm_fault_t from drm_gem_shmem_try_map_pmd()
  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 | 77 ++++++++++++++++++--------
 drivers/gpu/drm/imagination/pvr_gem.c  |  6 +-
 2 files changed, 57 insertions(+), 26 deletions(-)


base-commit: 6e53f6296065672f8a0c7f98b4b6c409dac382b4
-- 
2.52.0