Re: [PATCH v6 17/22] drm/shmem-helper: Add generic memory shrinker
From: Daniel Vetter
Date: Sun Jun 05 2022 - 14:45:45 EST
On Sun, 5 Jun 2022 at 20:32, Rob Clark <robdclark@xxxxxxxxx> wrote:
>
> On Sun, Jun 5, 2022 at 9:47 AM Daniel Vetter <daniel@xxxxxxxx> wrote:
> >
> > On Fri, 27 May 2022 at 01:55, Dmitry Osipenko
> > <dmitry.osipenko@xxxxxxxxxxxxx> wrote:
> > >
> > > Introduce a common DRM SHMEM shrinker framework that allows to reduce
> > > code duplication among DRM drivers by replacing theirs custom shrinker
> > > implementations with the generic shrinker.
> > >
> > > In order to start using DRM SHMEM shrinker drivers should:
> > >
> > > 1. Implement new evict() shmem object callback.
> > > 2. Register shrinker using drm_gem_shmem_shrinker_register(drm_device).
> > > 3. Use drm_gem_shmem_set_purgeable(shmem) and alike API functions to
> > > activate shrinking of shmem GEMs.
> > >
> > > This patch is based on a ideas borrowed from Rob's Clark MSM shrinker,
> > > Thomas' Zimmermann variant of SHMEM shrinker and Intel's i915 shrinker.
> > >
> > > Signed-off-by: Daniel Almeida <daniel.almeida@xxxxxxxxxxxxx>
> > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> >
> > So I guess I get a price for being blind since forever, because this
> > thing existed since at least 2013. I just stumbled over
> > llist_lru.[hc], a purpose built list helper for shrinkers. I think we
> > should try to adopt that so that our gpu shrinkers look more like
> > shrinkers for everything else.
>
> followup from a bit of irc discussion w/ danvet about list_lru:
>
> * It seems to be missing a way to bail out of iteration before
> nr_to_scan is hit.. which is going to be inconvenient if you
> want to allow active bos on the LRU but bail scanning once
> you encounter the first one.
>
> * Not sure if the numa node awareness is super useful for GEM
> bos
>
> First issue is perhaps not too hard to fix. But maybe a better
> idea is a drm_gem_lru helper type thing which is more tailored
> to GEM buffers?
Yeah I guess reusing list_lru isn't that good idea. So just
open-coding it for now, and then drm_gem_bo_lru or so if we need to
share it separately from shmem helpers with other drivers. Maybe will
be needed for ttm or so.
-Daniel
>
> BR,
> -R
>
> > Apologies for this, since I fear this might cause a bit of churn.
> > Hopefully it's all contained to the list manipulation code in shmem
> > helpers, I don't think this should leak any further.
> > -Daniel
> >
> > > ---
> > > drivers/gpu/drm/drm_gem_shmem_helper.c | 540 ++++++++++++++++--
> > > .../gpu/drm/panfrost/panfrost_gem_shrinker.c | 9 +-
> > > drivers/gpu/drm/virtio/virtgpu_drv.h | 3 +
> > > include/drm/drm_device.h | 4 +
> > > include/drm/drm_gem_shmem_helper.h | 87 ++-
> > > 5 files changed, 594 insertions(+), 49 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> > > index 555fe212bd98..4cd0b5913492 100644
> > > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> > > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> > > @@ -126,6 +126,42 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
> > > }
> > > EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
> > >
> > > +static bool drm_gem_shmem_is_evictable(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + return (shmem->madv >= 0) && shmem->evict &&
> > > + shmem->eviction_enabled && shmem->pages_use_count &&
> > > + !shmem->pages_pin_count && !shmem->base.dma_buf &&
> > > + !shmem->base.import_attach && shmem->sgt && !shmem->evicted;
> > > +}
> > > +
> > > +static void
> > > +drm_gem_shmem_update_pages_state(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + struct drm_gem_object *obj = &shmem->base;
> > > + struct drm_gem_shmem_shrinker *gem_shrinker = obj->dev->shmem_shrinker;
> > > +
> > > + dma_resv_assert_held(shmem->base.resv);
> > > +
> > > + if (!gem_shrinker || obj->import_attach)
> > > + return;
> > > +
> > > + mutex_lock(&gem_shrinker->lock);
> > > +
> > > + if (drm_gem_shmem_is_evictable(shmem) ||
> > > + drm_gem_shmem_is_purgeable(shmem))
> > > + list_move_tail(&shmem->madv_list, &gem_shrinker->lru_evictable);
> > > + else if (shmem->madv < 0)
> > > + list_del_init(&shmem->madv_list);
> > > + else if (shmem->evicted)
> > > + list_move_tail(&shmem->madv_list, &gem_shrinker->lru_evicted);
> > > + else if (!shmem->pages)
> > > + list_del_init(&shmem->madv_list);
> > > + else
> > > + list_move_tail(&shmem->madv_list, &gem_shrinker->lru_pinned);
> > > +
> > > + mutex_unlock(&gem_shrinker->lock);
> > > +}
> > > +
> > > /**
> > > * drm_gem_shmem_free - Free resources associated with a shmem GEM object
> > > * @shmem: shmem GEM object to free
> > > @@ -142,6 +178,9 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
> > > } else {
> > > dma_resv_lock(shmem->base.resv, NULL);
> > >
> > > + /* take out shmem GEM object from the memory shrinker */
> > > + drm_gem_shmem_madvise(shmem, -1);
> > > +
> > > WARN_ON(shmem->vmap_use_count);
> > >
> > > if (shmem->sgt) {
> > > @@ -150,7 +189,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
> > > sg_free_table(shmem->sgt);
> > > kfree(shmem->sgt);
> > > }
> > > - if (shmem->pages)
> > > + if (shmem->pages_use_count)
> > > drm_gem_shmem_put_pages(shmem);
> > >
> > > WARN_ON(shmem->pages_use_count);
> > > @@ -163,18 +202,82 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
> > > }
> > > EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
> > >
> > > -static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> > > +/**
> > > + * drm_gem_shmem_set_evictable() - Make GEM evictable by memory shrinker
> > > + * @shmem: shmem GEM object
> > > + *
> > > + * Tell memory shrinker that this GEM can be evicted. Initially eviction is
> > > + * disabled for all GEMs. If GEM was purged, then -ENOMEM is returned.
> > > + *
> > > + * Returns:
> > > + * 0 on success or a negative error code on failure.
> > > + */
> > > +int drm_gem_shmem_set_evictable(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + dma_resv_lock(shmem->base.resv, NULL);
> > > +
> > > + if (shmem->madv < 0)
> > > + return -ENOMEM;
> > > +
> > > + shmem->eviction_enabled = true;
> > > +
> > > + dma_resv_unlock(shmem->base.resv);
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_set_evictable);
> > > +
> > > +/**
> > > + * drm_gem_shmem_set_purgeable() - Make GEM purgeable by memory shrinker
> > > + * @shmem: shmem GEM object
> > > + *
> > > + * Tell memory shrinker that this GEM can be purged. Initially purging is
> > > + * disabled for all GEMs. If GEM was purged, then -ENOMEM is returned.
> > > + *
> > > + * Returns:
> > > + * 0 on success or a negative error code on failure.
> > > + */
> > > +int drm_gem_shmem_set_purgeable(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + dma_resv_lock(shmem->base.resv, NULL);
> > > +
> > > + if (shmem->madv < 0)
> > > + return -ENOMEM;
> > > +
> > > + shmem->purge_enabled = true;
> > > +
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > + dma_resv_unlock(shmem->base.resv);
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_set_purgeable);
> > > +
> > > +static int
> > > +drm_gem_shmem_acquire_pages(struct drm_gem_shmem_object *shmem)
> > > {
> > > struct drm_gem_object *obj = &shmem->base;
> > > struct page **pages;
> > >
> > > - if (shmem->pages_use_count++ > 0)
> > > + dma_resv_assert_held(shmem->base.resv);
> > > +
> > > + if (shmem->madv < 0) {
> > > + WARN_ON(shmem->pages);
> > > + return -ENOMEM;
> > > + }
> > > +
> > > + if (shmem->pages) {
> > > + WARN_ON(!shmem->evicted);
> > > return 0;
> > > + }
> > > +
> > > + if (WARN_ON(!shmem->pages_use_count))
> > > + return -EINVAL;
> > >
> > > pages = drm_gem_get_pages(obj);
> > > if (IS_ERR(pages)) {
> > > DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
> > > - shmem->pages_use_count = 0;
> > > return PTR_ERR(pages);
> > > }
> > >
> > > @@ -193,6 +296,58 @@ static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> > > return 0;
> > > }
> > >
> > > +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + int err;
> > > +
> > > + dma_resv_assert_held(shmem->base.resv);
> > > +
> > > + if (shmem->madv < 0)
> > > + return -ENOMEM;
> > > +
> > > + if (shmem->pages_use_count++ > 0) {
> > > + err = drm_gem_shmem_swap_in(shmem);
> > > + if (err)
> > > + goto err_zero_use;
> > > +
> > > + return 0;
> > > + }
> > > +
> > > + err = drm_gem_shmem_acquire_pages(shmem);
> > > + if (err)
> > > + goto err_zero_use;
> > > +
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > + return 0;
> > > +
> > > +err_zero_use:
> > > + shmem->pages_use_count = 0;
> > > +
> > > + return err;
> > > +}
> > > +
> > > +static void
> > > +drm_gem_shmem_release_pages(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + struct drm_gem_object *obj = &shmem->base;
> > > +
> > > + if (!shmem->pages) {
> > > + WARN_ON(!shmem->evicted && shmem->madv >= 0);
> > > + return;
> > > + }
> > > +
> > > +#ifdef CONFIG_X86
> > > + if (shmem->map_wc)
> > > + set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
> > > +#endif
> > > +
> > > + drm_gem_put_pages(obj, shmem->pages,
> > > + shmem->pages_mark_dirty_on_put,
> > > + shmem->pages_mark_accessed_on_put);
> > > + shmem->pages = NULL;
> > > +}
> > > +
> > > /*
> > > * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
> > > * @shmem: shmem GEM object
> > > @@ -201,8 +356,6 @@ static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> > > */
> > > void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> > > {
> > > - struct drm_gem_object *obj = &shmem->base;
> > > -
> > > dma_resv_assert_held(shmem->base.resv);
> > >
> > > if (WARN_ON_ONCE(!shmem->pages_use_count))
> > > @@ -211,15 +364,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> > > if (--shmem->pages_use_count > 0)
> > > return;
> > >
> > > -#ifdef CONFIG_X86
> > > - if (shmem->map_wc)
> > > - set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
> > > -#endif
> > > + drm_gem_shmem_release_pages(shmem);
> > >
> > > - drm_gem_put_pages(obj, shmem->pages,
> > > - shmem->pages_mark_dirty_on_put,
> > > - shmem->pages_mark_accessed_on_put);
> > > - shmem->pages = NULL;
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > }
> > > EXPORT_SYMBOL(drm_gem_shmem_put_pages);
> > >
> > > @@ -235,11 +382,17 @@ EXPORT_SYMBOL(drm_gem_shmem_put_pages);
> > > */
> > > int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
> > > {
> > > + int ret;
> > > +
> > > dma_resv_assert_held(shmem->base.resv);
> > >
> > > WARN_ON(shmem->base.import_attach);
> > >
> > > - return drm_gem_shmem_get_pages(shmem);
> > > + ret = drm_gem_shmem_get_pages(shmem);
> > > + if (!ret)
> > > + shmem->pages_pin_count++;
> > > +
> > > + return ret;
> > > }
> > > EXPORT_SYMBOL(drm_gem_shmem_pin);
> > >
> > > @@ -257,6 +410,8 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
> > > WARN_ON(shmem->base.import_attach);
> > >
> > > drm_gem_shmem_put_pages(shmem);
> > > +
> > > + shmem->pages_pin_count--;
> > > }
> > > EXPORT_SYMBOL(drm_gem_shmem_unpin);
> > >
> > > @@ -299,7 +454,7 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
> > > return 0;
> > > }
> > >
> > > - ret = drm_gem_shmem_get_pages(shmem);
> > > + ret = drm_gem_shmem_pin(shmem);
> > > if (ret)
> > > goto err_zero_use;
> > >
> > > @@ -322,7 +477,7 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
> > >
> > > err_put_pages:
> > > if (!obj->import_attach)
> > > - drm_gem_shmem_put_pages(shmem);
> > > + drm_gem_shmem_unpin(shmem);
> > > err_zero_use:
> > > shmem->vmap_use_count = 0;
> > >
> > > @@ -359,7 +514,7 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
> > > return;
> > >
> > > vunmap(shmem->vaddr);
> > > - drm_gem_shmem_put_pages(shmem);
> > > + drm_gem_shmem_unpin(shmem);
> > > }
> > >
> > > shmem->vaddr = NULL;
> > > @@ -403,41 +558,77 @@ int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
> > >
> > > madv = shmem->madv;
> > >
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > return (madv >= 0);
> > > }
> > > EXPORT_SYMBOL(drm_gem_shmem_madvise);
> > >
> > > -void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
> > > +/**
> > > + * drm_gem_shmem_swap_in() - Moves shmem GEM back to memory and enables
> > > + * hardware access to the memory.
> > > + * @shmem: shmem GEM object
> > > + *
> > > + * This function moves shmem GEM back to memory if it was previously evicted
> > > + * by the memory shrinker. The GEM is ready to use on success.
> > > + *
> > > + * Returns:
> > > + * 0 on success or a negative error code on failure.
> > > + */
> > > +int drm_gem_shmem_swap_in(struct drm_gem_shmem_object *shmem)
> > > {
> > > struct drm_gem_object *obj = &shmem->base;
> > > - struct drm_device *dev = obj->dev;
> > > + struct sg_table *sgt;
> > > + int err;
> > >
> > > dma_resv_assert_held(shmem->base.resv);
> > >
> > > - WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
> > > + if (shmem->evicted) {
> > > + err = drm_gem_shmem_acquire_pages(shmem);
> > > + if (err)
> > > + return err;
> > > +
> > > + sgt = drm_gem_shmem_get_sg_table(shmem);
> > > + if (IS_ERR(sgt))
> > > + return PTR_ERR(sgt);
> > > +
> > > + err = dma_map_sgtable(obj->dev->dev, sgt,
> > > + DMA_BIDIRECTIONAL, 0);
> > > + if (err) {
> > > + sg_free_table(sgt);
> > > + kfree(sgt);
> > > + return err;
> > > + }
> > >
> > > - dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
> > > - sg_free_table(shmem->sgt);
> > > - kfree(shmem->sgt);
> > > - shmem->sgt = NULL;
> > > + shmem->sgt = sgt;
> > > + shmem->evicted = false;
> > >
> > > - drm_gem_shmem_put_pages(shmem);
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > + }
> > >
> > > - shmem->madv = -1;
> > > + if (!shmem->pages)
> > > + return -ENOMEM;
> > >
> > > - drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
> > > - drm_gem_free_mmap_offset(obj);
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_swap_in);
> > >
> > > - /* Our goal here is to return as much of the memory as
> > > - * is possible back to the system as we are called from OOM.
> > > - * To do this we must instruct the shmfs to drop all of its
> > > - * backing pages, *now*.
> > > - */
> > > - shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
> > > +static void drm_gem_shmem_unpin_pages(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + struct drm_gem_object *obj = &shmem->base;
> > > + struct drm_device *dev = obj->dev;
> > >
> > > - invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
> > > + if (shmem->evicted)
> > > + return;
> > > +
> > > + dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
> > > + drm_gem_shmem_release_pages(shmem);
> > > + drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
> > > +
> > > + sg_free_table(shmem->sgt);
> > > + kfree(shmem->sgt);
> > > + shmem->sgt = NULL;
> > > }
> > > -EXPORT_SYMBOL(drm_gem_shmem_purge);
> > >
> > > /**
> > > * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
> > > @@ -488,22 +679,33 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
> > > vm_fault_t ret;
> > > struct page *page;
> > > pgoff_t page_offset;
> > > + bool pages_unpinned;
> > > + int err;
> > >
> > > /* We don't use vmf->pgoff since that has the fake offset */
> > > page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
> > >
> > > dma_resv_lock(shmem->base.resv, NULL);
> > >
> > > - if (page_offset >= num_pages ||
> > > - WARN_ON_ONCE(!shmem->pages) ||
> > > - shmem->madv < 0) {
> > > + /* Sanity-check that we have the pages pointer when it should present */
> > > + pages_unpinned = (shmem->evicted || shmem->madv < 0 || !shmem->pages_use_count);
> > > + WARN_ON_ONCE(!shmem->pages ^ pages_unpinned);
> > > +
> > > + if (page_offset >= num_pages || (!shmem->pages && !shmem->evicted)) {
> > > ret = VM_FAULT_SIGBUS;
> > > } else {
> > > + err = drm_gem_shmem_swap_in(shmem);
> > > + if (err) {
> > > + ret = VM_FAULT_OOM;
> > > + goto unlock;
> > > + }
> > > +
> > > page = shmem->pages[page_offset];
> > >
> > > ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
> > > }
> > >
> > > +unlock:
> > > dma_resv_unlock(shmem->base.resv);
> > >
> > > return ret;
> > > @@ -513,13 +715,15 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
> > > {
> > > struct drm_gem_object *obj = vma->vm_private_data;
> > > struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> > > - int ret;
> > >
> > > WARN_ON(shmem->base.import_attach);
> > >
> > > dma_resv_lock(shmem->base.resv, NULL);
> > > - ret = drm_gem_shmem_get_pages(shmem);
> > > - WARN_ON_ONCE(ret != 0);
> > > +
> > > + if (drm_gem_shmem_get_pages(shmem))
> > > + shmem->pages_use_count++;
> > > +
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > dma_resv_unlock(shmem->base.resv);
> > >
> > > drm_gem_vm_open(vma);
> > > @@ -583,6 +787,8 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
> > > void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
> > > struct drm_printer *p, unsigned int indent)
> > > {
> > > + drm_printf_indent(p, indent, "eviction_enabled=%d\n", shmem->eviction_enabled);
> > > + drm_printf_indent(p, indent, "purge_enabled=%d\n", shmem->purge_enabled);
> > > drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
> > >
> > > if (shmem->base.import_attach)
> > > @@ -592,7 +798,9 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
> > > drm_printf_indent(p, indent, "vmap_use_count=%u\n",
> > > shmem->vmap_use_count);
> > >
> > > + drm_printf_indent(p, indent, "evicted=%d\n", shmem->evicted);
> > > drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
> > > + drm_printf_indent(p, indent, "madv=%d\n", shmem->madv);
> > > }
> > > EXPORT_SYMBOL(drm_gem_shmem_print_info);
> > >
> > > @@ -667,6 +875,8 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
> > >
> > > shmem->sgt = sgt;
> > >
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > dma_resv_unlock(shmem->base.resv);
> > >
> > > return sgt;
> > > @@ -717,6 +927,250 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
> > > }
> > > EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
> > >
> > > +static struct drm_gem_shmem_shrinker *
> > > +to_drm_shrinker(struct shrinker *shrinker)
> > > +{
> > > + return container_of(shrinker, struct drm_gem_shmem_shrinker, base);
> > > +}
> > > +
> > > +static unsigned long
> > > +drm_gem_shmem_shrinker_count_objects(struct shrinker *shrinker,
> > > + struct shrink_control *sc)
> > > +{
> > > + struct drm_gem_shmem_shrinker *gem_shrinker = to_drm_shrinker(shrinker);
> > > + struct drm_gem_shmem_object *shmem;
> > > + unsigned long count = 0;
> > > +
> > > + if (!mutex_trylock(&gem_shrinker->lock))
> > > + return 0;
> > > +
> > > + list_for_each_entry(shmem, &gem_shrinker->lru_evictable, madv_list) {
> > > + count += shmem->base.size;
> > > +
> > > + if (count >= SHRINK_EMPTY)
> > > + break;
> > > + }
> > > +
> > > + mutex_unlock(&gem_shrinker->lock);
> > > +
> > > + if (count >= SHRINK_EMPTY)
> > > + return SHRINK_EMPTY - 1;
> > > +
> > > + return count ?: SHRINK_EMPTY;
> > > +}
> > > +
> > > +int drm_gem_shmem_evict(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + WARN_ON(!drm_gem_shmem_is_evictable(shmem));
> > > + WARN_ON(shmem->evicted);
> > > +
> > > + drm_gem_shmem_unpin_pages(shmem);
> > > +
> > > + shmem->evicted = true;
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_evict);
> > > +
> > > +int drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + struct drm_gem_object *obj = &shmem->base;
> > > +
> > > + WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
> > > +
> > > + drm_gem_shmem_unpin_pages(shmem);
> > > + drm_gem_free_mmap_offset(obj);
> > > +
> > > + /* Our goal here is to return as much of the memory as
> > > + * is possible back to the system as we are called from OOM.
> > > + * To do this we must instruct the shmfs to drop all of its
> > > + * backing pages, *now*.
> > > + */
> > > + shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
> > > +
> > > + invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
> > > +
> > > + shmem->madv = -1;
> > > + shmem->evicted = false;
> > > + drm_gem_shmem_update_pages_state(shmem);
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_purge);
> > > +
> > > +static unsigned long
> > > +drm_gem_shmem_shrinker_run_objects_scan(struct shrinker *shrinker,
> > > + unsigned long nr_to_scan,
> > > + bool *lock_contention,
> > > + bool evict)
> > > +{
> > > + struct drm_gem_shmem_shrinker *gem_shrinker = to_drm_shrinker(shrinker);
> > > + struct drm_gem_shmem_object *shmem;
> > > + struct list_head still_in_list;
> > > + struct drm_gem_object *obj;
> > > + unsigned long freed = 0;
> > > + size_t page_count;
> > > + int err;
> > > +
> > > + INIT_LIST_HEAD(&still_in_list);
> > > +
> > > + mutex_lock(&gem_shrinker->lock);
> > > +
> > > + while (freed < nr_to_scan) {
> > > + shmem = list_first_entry_or_null(&gem_shrinker->lru_evictable,
> > > + typeof(*shmem), madv_list);
> > > + if (!shmem)
> > > + break;
> > > +
> > > + obj = &shmem->base;
> > > + page_count = obj->size >> PAGE_SHIFT;
> > > + list_move_tail(&shmem->madv_list, &still_in_list);
> > > +
> > > + if (evict) {
> > > + if (!drm_gem_shmem_is_evictable(shmem) ||
> > > + get_nr_swap_pages() < page_count)
> > > + continue;
> > > + } else {
> > > + if (!drm_gem_shmem_is_purgeable(shmem))
> > > + continue;
> > > + }
> > > +
> > > + /*
> > > + * If it's in the process of being freed, gem_object->free()
> > > + * may be blocked on lock waiting to remove it. So just
> > > + * skip it.
> > > + */
> > > + if (!kref_get_unless_zero(&obj->refcount))
> > > + continue;
> > > +
> > > + mutex_unlock(&gem_shrinker->lock);
> > > +
> > > + /* prevent racing with job-submission code paths */
> > > + if (!dma_resv_trylock(obj->resv)) {
> > > + *lock_contention |= true;
> > > + goto shrinker_lock;
> > > + }
> > > +
> > > + /* prevent racing with the dma-buf importing/exporting */
> > > + if (!mutex_trylock(&gem_shrinker->dev->object_name_lock)) {
> > > + *lock_contention |= true;
> > > + goto resv_unlock;
> > > + }
> > > +
> > > + /* check whether h/w uses this object */
> > > + if (!dma_resv_test_signaled(obj->resv, DMA_RESV_USAGE_WRITE))
> > > + goto object_name_unlock;
> > > +
> > > + /* re-check whether eviction status hasn't changed */
> > > + if (!drm_gem_shmem_is_evictable(shmem) &&
> > > + !drm_gem_shmem_is_purgeable(shmem))
> > > + goto object_name_unlock;
> > > +
> > > + err = shmem->evict(shmem);
> > > + if (!err)
> > > + freed += obj->size >> PAGE_SHIFT;
> > > +
> > > +object_name_unlock:
> > > + mutex_unlock(&gem_shrinker->dev->object_name_lock);
> > > +resv_unlock:
> > > + dma_resv_unlock(obj->resv);
> > > +shrinker_lock:
> > > + drm_gem_object_put(&shmem->base);
> > > + mutex_lock(&gem_shrinker->lock);
> > > + }
> > > +
> > > + list_splice_tail(&still_in_list, &gem_shrinker->lru_evictable);
> > > +
> > > + mutex_unlock(&gem_shrinker->lock);
> > > +
> > > + return freed;
> > > +}
> > > +
> > > +static unsigned long
> > > +drm_gem_shmem_shrinker_scan_objects(struct shrinker *shrinker,
> > > + struct shrink_control *sc)
> > > +{
> > > + unsigned long nr_to_scan = sc->nr_to_scan;
> > > + bool lock_contention = false;
> > > + unsigned long freed;
> > > +
> > > + /* purge as many objects as we can */
> > > + freed = drm_gem_shmem_shrinker_run_objects_scan(shrinker, nr_to_scan,
> > > + &lock_contention, false);
> > > +
> > > + /* evict as many objects as we can */
> > > + if (freed < nr_to_scan)
> > > + freed += drm_gem_shmem_shrinker_run_objects_scan(shrinker,
> > > + nr_to_scan - freed,
> > > + &lock_contention,
> > > + true);
> > > +
> > > + return (!freed && !lock_contention) ? SHRINK_STOP : freed;
> > > +}
> > > +
> > > +/**
> > > + * drm_gem_shmem_shrinker_register() - Register shmem shrinker
> > > + * @dev: DRM device
> > > + *
> > > + * Returns:
> > > + * 0 on success or a negative error code on failure.
> > > + */
> > > +int drm_gem_shmem_shrinker_register(struct drm_device *dev)
> > > +{
> > > + struct drm_gem_shmem_shrinker *gem_shrinker;
> > > + int err;
> > > +
> > > + if (WARN_ON(dev->shmem_shrinker))
> > > + return -EBUSY;
> > > +
> > > + gem_shrinker = kzalloc(sizeof(*gem_shrinker), GFP_KERNEL);
> > > + if (!gem_shrinker)
> > > + return -ENOMEM;
> > > +
> > > + gem_shrinker->base.count_objects = drm_gem_shmem_shrinker_count_objects;
> > > + gem_shrinker->base.scan_objects = drm_gem_shmem_shrinker_scan_objects;
> > > + gem_shrinker->base.seeks = DEFAULT_SEEKS;
> > > + gem_shrinker->dev = dev;
> > > +
> > > + INIT_LIST_HEAD(&gem_shrinker->lru_evictable);
> > > + INIT_LIST_HEAD(&gem_shrinker->lru_evicted);
> > > + INIT_LIST_HEAD(&gem_shrinker->lru_pinned);
> > > + mutex_init(&gem_shrinker->lock);
> > > +
> > > + dev->shmem_shrinker = gem_shrinker;
> > > +
> > > + err = register_shrinker(&gem_shrinker->base);
> > > + if (err) {
> > > + dev->shmem_shrinker = NULL;
> > > + kfree(gem_shrinker);
> > > + return err;
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_shrinker_register);
> > > +
> > > +/**
> > > + * drm_gem_shmem_shrinker_unregister() - Unregister shmem shrinker
> > > + * @dev: DRM device
> > > + */
> > > +void drm_gem_shmem_shrinker_unregister(struct drm_device *dev)
> > > +{
> > > + struct drm_gem_shmem_shrinker *gem_shrinker = dev->shmem_shrinker;
> > > +
> > > + if (gem_shrinker) {
> > > + unregister_shrinker(&gem_shrinker->base);
> > > + WARN_ON(!list_empty(&gem_shrinker->lru_evictable));
> > > + WARN_ON(!list_empty(&gem_shrinker->lru_evicted));
> > > + WARN_ON(!list_empty(&gem_shrinker->lru_pinned));
> > > + mutex_destroy(&gem_shrinker->lock);
> > > + dev->shmem_shrinker = NULL;
> > > + kfree(gem_shrinker);
> > > + }
> > > +}
> > > +EXPORT_SYMBOL_GPL(drm_gem_shmem_shrinker_unregister);
> > > +
> > > MODULE_DESCRIPTION("DRM SHMEM memory-management helpers");
> > > MODULE_IMPORT_NS(DMA_BUF);
> > > MODULE_LICENSE("GPL v2");
> > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > > index a4bedfeb2ec4..7cc32556f908 100644
> > > --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > > +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > > @@ -15,6 +15,13 @@
> > > #include "panfrost_gem.h"
> > > #include "panfrost_mmu.h"
> > >
> > > +static bool panfrost_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
> > > +{
> > > + return (shmem->madv > 0) &&
> > > + !shmem->pages_pin_count && shmem->sgt &&
> > > + !shmem->base.dma_buf && !shmem->base.import_attach;
> > > +}
> > > +
> > > static unsigned long
> > > panfrost_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
> > > {
> > > @@ -27,7 +34,7 @@ panfrost_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc
> > > return 0;
> > >
> > > list_for_each_entry(shmem, &pfdev->shrinker_list, madv_list) {
> > > - if (drm_gem_shmem_is_purgeable(shmem))
> > > + if (panfrost_gem_shmem_is_purgeable(shmem))
> > > count += shmem->base.size >> PAGE_SHIFT;
> > > }
> > >
> > > diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> > > index b2d93cb12ebf..81bacc7e1873 100644
> > > --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> > > +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> > > @@ -89,6 +89,7 @@ struct virtio_gpu_object {
> > > uint32_t hw_res_handle;
> > > bool dumb;
> > > bool created;
> > > + bool detached;
> > > bool host3d_blob, guest_blob;
> > > uint32_t blob_mem, blob_flags;
> > >
> > > @@ -453,6 +454,8 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
> > >
> > > bool virtio_gpu_is_shmem(struct virtio_gpu_object *bo);
> > >
> > > +int virtio_gpu_reattach_shmem_object(struct virtio_gpu_object *bo);
> > > +
> > > int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev,
> > > uint32_t *resid);
> > > /* virtgpu_prime.c */
> > > diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> > > index 9923c7a6885e..929546cad894 100644
> > > --- a/include/drm/drm_device.h
> > > +++ b/include/drm/drm_device.h
> > > @@ -16,6 +16,7 @@ struct drm_vblank_crtc;
> > > struct drm_vma_offset_manager;
> > > struct drm_vram_mm;
> > > struct drm_fb_helper;
> > > +struct drm_gem_shmem_shrinker;
> > >
> > > struct inode;
> > >
> > > @@ -277,6 +278,9 @@ struct drm_device {
> > > /** @vram_mm: VRAM MM memory manager */
> > > struct drm_vram_mm *vram_mm;
> > >
> > > + /** @shmem_shrinker: SHMEM GEM memory shrinker */
> > > + struct drm_gem_shmem_shrinker *shmem_shrinker;
> > > +
> > > /**
> > > * @switch_power_state:
> > > *
> > > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
> > > index 9a8983ee8abe..62c640678a91 100644
> > > --- a/include/drm/drm_gem_shmem_helper.h
> > > +++ b/include/drm/drm_gem_shmem_helper.h
> > > @@ -6,6 +6,7 @@
> > > #include <linux/fs.h>
> > > #include <linux/mm.h>
> > > #include <linux/mutex.h>
> > > +#include <linux/shrinker.h>
> > >
> > > #include <drm/drm_file.h>
> > > #include <drm/drm_gem.h>
> > > @@ -15,6 +16,7 @@
> > > struct dma_buf_attachment;
> > > struct drm_mode_create_dumb;
> > > struct drm_printer;
> > > +struct drm_device;
> > > struct sg_table;
> > >
> > > /**
> > > @@ -39,12 +41,21 @@ struct drm_gem_shmem_object {
> > > */
> > > unsigned int pages_use_count;
> > >
> > > + /**
> > > + * @pages_pin_count:
> > > + *
> > > + * Reference count on the pinned pages table.
> > > + * The pages can be evicted by memory shrinker
> > > + * when the count reaches zero.
> > > + */
> > > + unsigned int pages_pin_count;
> > > +
> > > /**
> > > * @madv: State for madvise
> > > *
> > > * 0 is active/inuse.
> > > + * 1 is not-needed/can-be-purged
> > > * A negative value is the object is purged.
> > > - * Positive values are driver specific and not used by the helpers.
> > > */
> > > int madv;
> > >
> > > @@ -91,6 +102,39 @@ struct drm_gem_shmem_object {
> > > * @map_wc: map object write-combined (instead of using shmem defaults).
> > > */
> > > bool map_wc;
> > > +
> > > + /**
> > > + * @eviction_enabled:
> > > + *
> > > + * The shmem pages can be evicted only if @eviction_enabled is set to true.
> > > + * Used internally by memory shrinker.
> > > + */
> > > + bool eviction_enabled;
> > > +
> > > + /**
> > > + * @purge_enabled:
> > > + *
> > > + * The shmem pages can be purged only if @purge_enabled is set to true.
> > > + * Used internally by memory shrinker.
> > > + */
> > > + bool purge_enabled;
> > > +
> > > + /**
> > > + * @evicted: True if shmem pages are evicted by the memory shrinker.
> > > + * Used internally by memory shrinker.
> > > + */
> > > + bool evicted;
> > > +
> > > + /**
> > > + * @evict:
> > > + *
> > > + * Invoked by shmem shrinker before evicting shmem GEM from memory.
> > > + * GEM's DMA reservation is kept locked by the shrinker. This is
> > > + * optional callback that should be specified by drivers.
> > > + *
> > > + * Returns 0 on success, or -errno on error.
> > > + */
> > > + int (*evict)(struct drm_gem_shmem_object *shmem);
> > > };
> > >
> > > #define to_drm_gem_shmem_obj(obj) \
> > > @@ -110,14 +154,21 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
> > >
> > > int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv);
> > >
> > > +int drm_gem_shmem_set_purgeable(struct drm_gem_shmem_object *shmem);
> > > +int drm_gem_shmem_set_evictable(struct drm_gem_shmem_object *shmem);
> > > +
> > > static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
> > > {
> > > - return (shmem->madv > 0) &&
> > > - !shmem->vmap_use_count && shmem->sgt &&
> > > - !shmem->base.dma_buf && !shmem->base.import_attach;
> > > + return (shmem->madv > 0) && shmem->evict &&
> > > + shmem->purge_enabled && shmem->pages_use_count &&
> > > + !shmem->pages_pin_count && !shmem->base.dma_buf &&
> > > + !shmem->base.import_attach && (shmem->sgt || shmem->evicted);
> > > }
> > >
> > > -void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem);
> > > +int drm_gem_shmem_swap_in(struct drm_gem_shmem_object *shmem);
> > > +
> > > +int drm_gem_shmem_evict(struct drm_gem_shmem_object *shmem);
> > > +int drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem);
> > >
> > > struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem);
> > > struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem);
> > > @@ -260,6 +311,32 @@ static inline int drm_gem_shmem_object_mmap(struct drm_gem_object *obj, struct v
> > > return drm_gem_shmem_mmap(shmem, vma);
> > > }
> > >
> > > +/**
> > > + * struct drm_gem_shmem_shrinker - Generic memory shrinker for shmem GEMs
> > > + */
> > > +struct drm_gem_shmem_shrinker {
> > > + /** @base: Shrinker for purging shmem GEM objects */
> > > + struct shrinker base;
> > > +
> > > + /** @lock: Protects @lru_* */
> > > + struct mutex lock;
> > > +
> > > + /** @lru_pinned: List of pinned shmem GEM objects */
> > > + struct list_head lru_pinned;
> > > +
> > > + /** @lru_evictable: List of shmem GEM objects to be evicted */
> > > + struct list_head lru_evictable;
> > > +
> > > + /** @lru_evicted: List of evicted shmem GEM objects */
> > > + struct list_head lru_evicted;
> > > +
> > > + /** @dev: DRM device that uses this shrinker */
> > > + struct drm_device *dev;
> > > +};
> > > +
> > > +int drm_gem_shmem_shrinker_register(struct drm_device *dev);
> > > +void drm_gem_shmem_shrinker_unregister(struct drm_device *dev);
> > > +
> > > /*
> > > * Driver ops
> > > */
> > > --
> > > 2.35.3
> > >
> >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch