Re: [PATCH v6 17/22] drm/shmem-helper: Add generic memory shrinker

Christian König
2022-06-06T10:57:36Z

Am 05.06.22 um 18:47 schrieb Daniel Vetter:
> On Fri, 27 May 2022 at 01:55, Dmitry Osipenko
> <dmitry.osipenko@collabora.com> 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@collabora.com>
>> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> 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.

What the heck are you talking about?

I can't find any llist_lru.[hc] in the linux kernel sources.

Christian.

>
> 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
>>
>