On Tue, 27 Jan 2026 14:16:38 +0100 Thomas Zimmermann <[email protected]> wrote:
> On successful vmap, set the page_mark_accessed_on_put and _dirty_on_put > flags in the gem-shmem object. Signals that the contained pages require > LRU and dirty tracking when they are being released back to SHMEM. Clear > these flags on put, so that buffer remains quiet until the next call to > vmap. There's no means of handling dirty status in vmap as there's no > write-only mapping available. > > Both flags, _accessed_on_put and _dirty_on_put, have always been part of > the gem-shmem object, but never used much. So most drivers did not track > the page status correctly. > > Only the v3d and imagination drivers make limited use of _dirty_on_put. In > the case of imagination, move the flag setting from init to cleanup. This > ensures writeback of modified pages but does not interfere with the > internal vmap/vunmap calls. V3d already implements this behaviour. > > Signed-off-by: Thomas Zimmermann <[email protected]> The gem-shmem changes are Reviewed-by: Boris Brezillon <[email protected]> > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++++ > drivers/gpu/drm/imagination/pvr_gem.c | 6 ++++-- > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c > b/drivers/gpu/drm/drm_gem_shmem_helper.c > index 30cd34d3a111..8c07a8f81322 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -265,6 +265,8 @@ void drm_gem_shmem_put_pages_locked(struct > drm_gem_shmem_object *shmem) > shmem->pages_mark_dirty_on_put, > shmem->pages_mark_accessed_on_put); > shmem->pages = NULL; > + shmem->pages_mark_accessed_on_put = false; > + shmem->pages_mark_dirty_on_put = false; > } > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); > @@ -397,6 +399,8 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object > *shmem, > } else { > iosys_map_set_vaddr(map, shmem->vaddr); > refcount_set(&shmem->vmap_use_count, 1); > + shmem->pages_mark_accessed_on_put = true; > + shmem->pages_mark_dirty_on_put = true; > } > } > > diff --git a/drivers/gpu/drm/imagination/pvr_gem.c > b/drivers/gpu/drm/imagination/pvr_gem.c > index c07c9a915190..307b02c916d4 100644 > --- a/drivers/gpu/drm/imagination/pvr_gem.c > +++ b/drivers/gpu/drm/imagination/pvr_gem.c > @@ -25,7 +25,10 @@ > > static void pvr_gem_object_free(struct drm_gem_object *obj) > { > - drm_gem_shmem_object_free(obj); > + struct drm_gem_shmem_object *shmem_obj = to_drm_gem_shmem_obj(obj); > + > + shmem_obj->pages_mark_dirty_on_put = true; > + drm_gem_shmem_free(shmem_obj); > } > > static struct dma_buf *pvr_gem_export(struct drm_gem_object *obj, int flags) > @@ -363,7 +366,6 @@ pvr_gem_object_create(struct pvr_device *pvr_dev, size_t > size, u64 flags) > if (IS_ERR(shmem_obj)) > return ERR_CAST(shmem_obj); > > - shmem_obj->pages_mark_dirty_on_put = true; > shmem_obj->map_wc = !(flags & PVR_BO_CPU_CACHED); > pvr_obj = shmem_gem_to_pvr_gem(shmem_obj); > pvr_obj->flags = flags;
