Message-ID: <d1f856c7-47dd-4f1d-a124-973064dcd1f0@suse.de>
Date: Tue, 4 Mar 2025 11:29:47 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Dmitry Osipenko <dmitry.osipenko@...labora.com>,
 David Airlie <airlied@...il.com>, Gerd Hoffmann <kraxel@...hat.com>,
 Gurchetan Singh <gurchetansingh@...omium.org>, Chia-I Wu
 <olvaffe@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>,
 Christian König <christian.koenig@....com>,
 Qiang Yu <yuq825@...il.com>, Steven Price <steven.price@....com>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Emma Anholt <emma@...olt.net>, Melissa Wen <mwen@...lia.com>
Cc: kernel@...labora.com, linux-kernel@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v19 22/30] drm/shmem-helper: Add common memory shrinker

Hi

Am 05.01.24 um 19:46 schrieb Dmitry Osipenko:
> Introduce common drm-shmem shrinker for DRM drivers.

What's the status of this patch?

Best regards
Thomas

>
> To start using drm-shmem shrinker drivers should do the following:
>
> 1. Implement evict() callback of GEM object where driver should check
>     whether object is purgeable or evictable using drm-shmem helpers and
>     perform the shrinking action
>
> 2. Initialize drm-shmem internals using drmm_gem_shmem_init(drm_device),
>     which will register drm-shmem shrinker
>
> 3. Implement madvise IOCTL that will use drm_gem_shmem_madvise()
>
> Signed-off-by: Daniel Almeida <daniel.almeida@...labora.com>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> ---
>   drivers/gpu/drm/drm_gem_shmem_helper.c        | 365 +++++++++++++++++-
>   drivers/gpu/drm/panfrost/panfrost_gem.c       |   3 +-
>   .../gpu/drm/panfrost/panfrost_gem_shrinker.c  |  13 +-
>   include/drm/drm_device.h                      |  10 +-
>   include/drm/drm_gem_shmem_helper.h            |  68 +++-
>   5 files changed, 433 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index ff5437ab2c95..59cebd1e35af 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -20,6 +20,7 @@
>   #include <drm/drm_device.h>
>   #include <drm/drm_drv.h>
>   #include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_managed.h>
>   #include <drm/drm_prime.h>
>   #include <drm/drm_print.h>
>   
> @@ -128,11 +129,49 @@ 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->base.funcs->evict &&
> +		refcount_read(&shmem->pages_use_count) &&
> +		!refcount_read(&shmem->pages_pin_count) &&
> +		!shmem->base.dma_buf && !shmem->base.import_attach &&
> +		!shmem->evicted;
> +}
> +
> +static void
> +drm_gem_shmem_shrinker_update_lru_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	struct drm_gem_object *obj = &shmem->base;
> +	struct drm_gem_shmem *shmem_mm = obj->dev->shmem_mm;
> +	struct drm_gem_shmem_shrinker *shmem_shrinker = &shmem_mm->shrinker;
> +
> +	dma_resv_assert_held(shmem->base.resv);
> +
> +	if (!shmem_shrinker || obj->import_attach)
> +		return;
> +
> +	if (shmem->madv < 0)
> +		drm_gem_lru_remove(&shmem->base);
> +	else if (drm_gem_shmem_is_evictable(shmem) || drm_gem_shmem_is_purgeable(shmem))
> +		drm_gem_lru_move_tail(&shmem_shrinker->lru_evictable, &shmem->base);
> +	else if (shmem->evicted)
> +		drm_gem_lru_move_tail(&shmem_shrinker->lru_evicted, &shmem->base);
> +	else if (!shmem->pages)
> +		drm_gem_lru_remove(&shmem->base);
> +	else
> +		drm_gem_lru_move_tail(&shmem_shrinker->lru_pinned, &shmem->base);
> +}
> +
>   static void
>   drm_gem_shmem_free_pages(struct drm_gem_shmem_object *shmem)
>   {
>   	struct drm_gem_object *obj = &shmem->base;
>   
> +	if (!shmem->pages) {
> +		drm_WARN_ON(obj->dev, !shmem->evicted && shmem->madv >= 0);
> +		return;
> +	}
> +
>   	if (shmem->sgt) {
>   		dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
>   				  DMA_BIDIRECTIONAL, 0);
> @@ -175,15 +214,26 @@ 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_locked(struct drm_gem_shmem_object *shmem)
> +static int
> +drm_gem_shmem_acquire_pages(struct drm_gem_shmem_object *shmem)
>   {
>   	struct drm_gem_object *obj = &shmem->base;
>   	struct page **pages;
>   
> +	if (drm_WARN_ON(obj->dev, obj->import_attach))
> +		return -EINVAL;
> +
>   	dma_resv_assert_held(shmem->base.resv);
>   
> -	if (refcount_inc_not_zero(&shmem->pages_use_count))
> +	if (shmem->madv < 0) {
> +		drm_WARN_ON(obj->dev, shmem->pages);
> +		return -ENOMEM;
> +	}
> +
> +	if (shmem->pages) {
> +		drm_WARN_ON(obj->dev, !shmem->evicted);
>   		return 0;
> +	}
>   
>   	pages = drm_gem_get_pages(obj);
>   	if (IS_ERR(pages)) {
> @@ -204,8 +254,29 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
>   
>   	shmem->pages = pages;
>   
> +	return 0;
> +}
> +
> +static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	int err;
> +
> +	dma_resv_assert_held(shmem->base.resv);
> +
> +	if (shmem->madv < 0)
> +		return -ENOMEM;
> +
> +	if (refcount_inc_not_zero(&shmem->pages_use_count))
> +		return 0;
> +
> +	err = drm_gem_shmem_acquire_pages(shmem);
> +	if (err)
> +		return err;
> +
>   	refcount_set(&shmem->pages_use_count, 1);
>   
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
> +
>   	return 0;
>   }
>   
> @@ -222,6 +293,8 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
>   
>   	if (refcount_dec_and_test(&shmem->pages_use_count))
>   		drm_gem_shmem_free_pages(shmem);
> +
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
>   }
>   EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked);
>   
> @@ -266,6 +339,11 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages);
>    *
>    * This function Increases the use count and allocates the backing pages if
>    * use-count equals to zero.
> + *
> + * Note that this function doesn't pin pages in memory. If your driver
> + * uses drm-shmem shrinker, then it's free to relocate pages to swap.
> + * Getting pages only guarantees that pages are allocated, and not that
> + * pages reside in memory. In order to pin pages use drm_gem_shmem_pin().
>    */
>   int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
>   {
> @@ -291,6 +369,10 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
>   	if (refcount_inc_not_zero(&shmem->pages_pin_count))
>   		return 0;
>   
> +	ret = drm_gem_shmem_swapin_locked(shmem);
> +	if (ret)
> +		return ret;
> +
>   	ret = drm_gem_shmem_get_pages_locked(shmem);
>   	if (!ret)
>   		refcount_set(&shmem->pages_pin_count, 1);
> @@ -489,29 +571,48 @@ int drm_gem_shmem_madvise_locked(struct drm_gem_shmem_object *shmem, int madv)
>   
>   	madv = shmem->madv;
>   
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
> +
>   	return (madv >= 0);
>   }
>   EXPORT_SYMBOL_GPL(drm_gem_shmem_madvise_locked);
>   
> -void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
> +int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
>   {
>   	struct drm_gem_object *obj = &shmem->base;
> -	struct drm_device *dev = obj->dev;
> +	int ret;
>   
> -	dma_resv_assert_held(shmem->base.resv);
> +	ret = dma_resv_lock_interruptible(obj->resv, NULL);
> +	if (ret)
> +		return ret;
>   
> -	drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
> +	ret = drm_gem_shmem_madvise_locked(shmem, madv);
> +	dma_resv_unlock(obj->resv);
>   
> -	dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
> -	sg_free_table(shmem->sgt);
> -	kfree(shmem->sgt);
> -	shmem->sgt = NULL;
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_madvise);
>   
> -	drm_gem_shmem_put_pages_locked(shmem);
> +static void
> +drm_gem_shmem_shrinker_put_pages_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	struct drm_gem_object *obj = &shmem->base;
> +	struct drm_device *dev = obj->dev;
>   
> -	shmem->madv = -1;
> +	dma_resv_assert_held(shmem->base.resv);
>   
> +	if (shmem->evicted)
> +		return;
> +
> +	drm_gem_shmem_free_pages(shmem);
>   	drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
> +}
> +
> +void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	struct drm_gem_object *obj = &shmem->base;
> +
> +	drm_gem_shmem_shrinker_put_pages_locked(shmem);
>   	drm_gem_free_mmap_offset(obj);
>   
>   	/* Our goal here is to return as much of the memory as
> @@ -522,9 +623,45 @@ void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
>   	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_shrinker_update_lru_locked(shmem);
>   }
>   EXPORT_SYMBOL_GPL(drm_gem_shmem_purge_locked);
>   
> +/**
> + * drm_gem_shmem_swapin_locked() - 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_swapin_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	int err;
> +
> +	dma_resv_assert_held(shmem->base.resv);
> +
> +	if (!shmem->evicted)
> +		return 0;
> +
> +	err = drm_gem_shmem_acquire_pages(shmem);
> +	if (err)
> +		return err;
> +
> +	shmem->evicted = false;
> +
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_swapin_locked);
> +
>   /**
>    * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
>    * @file: DRM file structure to create the dumb buffer for
> @@ -571,22 +708,32 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
>   	vm_fault_t ret;
>   	struct page *page;
>   	pgoff_t page_offset;
> +	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 ||
> -	    drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
> -	    shmem->madv < 0) {
> +	err = drm_gem_shmem_swapin_locked(shmem);
> +	if (err) {
> +		ret = VM_FAULT_OOM;
> +		goto unlock;
> +	}
> +
> +	if (page_offset >= num_pages || !shmem->pages) {
>   		ret = VM_FAULT_SIGBUS;
>   	} else {
> +		/*
> +		 * shmem->pages is guaranteed to be valid while reservation
> +		 * lock is held and drm_gem_shmem_swapin_locked() succeeds.
> +		 */
>   		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;
> @@ -609,6 +756,7 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
>   	drm_WARN_ON_ONCE(obj->dev,
>   			 !refcount_inc_not_zero(&shmem->pages_use_count));
>   
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
>   	dma_resv_unlock(shmem->base.resv);
>   
>   	drm_gem_vm_open(vma);
> @@ -694,7 +842,9 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
>   	drm_printf_indent(p, indent, "pages_pin_count=%u\n", refcount_read(&shmem->pages_pin_count));
>   	drm_printf_indent(p, indent, "pages_use_count=%u\n", refcount_read(&shmem->pages_use_count));
>   	drm_printf_indent(p, indent, "vmap_use_count=%u\n", refcount_read(&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_GPL(drm_gem_shmem_print_info);
>   
> @@ -784,8 +934,13 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
>    */
>   struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
>   {
> -	int ret;
> +	struct drm_gem_object *obj = &shmem->base;
>   	struct sg_table *sgt;
> +	int ret;
> +
> +	if (drm_WARN_ON(obj->dev, drm_gem_shmem_is_evictable(shmem)) ||
> +	    drm_WARN_ON(obj->dev, drm_gem_shmem_is_purgeable(shmem)))
> +		return ERR_PTR(-EBUSY);
>   
>   	ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
>   	if (ret)
> @@ -832,6 +987,184 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
>   }
>   EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
>   
> +static unsigned long
> +drm_gem_shmem_shrinker_count_objects(struct shrinker *shrinker,
> +				     struct shrink_control *sc)
> +{
> +	struct drm_gem_shmem_shrinker *shmem_shrinker = shrinker->private_data;
> +	unsigned long count = shmem_shrinker->lru_evictable.count;
> +
> +	if (count >= SHRINK_EMPTY)
> +		return SHRINK_EMPTY - 1;
> +
> +	return count ?: SHRINK_EMPTY;
> +}
> +
> +void drm_gem_shmem_evict_locked(struct drm_gem_shmem_object *shmem)
> +{
> +	struct drm_gem_object *obj = &shmem->base;
> +
> +	drm_WARN_ON(obj->dev, !drm_gem_shmem_is_evictable(shmem));
> +	drm_WARN_ON(obj->dev, shmem->evicted);
> +
> +	drm_gem_shmem_shrinker_put_pages_locked(shmem);
> +
> +	shmem->evicted = true;
> +	drm_gem_shmem_shrinker_update_lru_locked(shmem);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_evict_locked);
> +
> +static bool drm_gem_shmem_shrinker_evict_locked(struct drm_gem_object *obj)
> +{
> +	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +	int err;
> +
> +	if (!drm_gem_shmem_is_evictable(shmem) ||
> +	    get_nr_swap_pages() < obj->size >> PAGE_SHIFT)
> +		return false;
> +
> +	err = drm_gem_evict_locked(obj);
> +	if (err)
> +		return false;
> +
> +	return true;
> +}
> +
> +static bool drm_gem_shmem_shrinker_purge_locked(struct drm_gem_object *obj)
> +{
> +	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +	int err;
> +
> +	if (!drm_gem_shmem_is_purgeable(shmem))
> +		return false;
> +
> +	err = drm_gem_evict_locked(obj);
> +	if (err)
> +		return false;
> +
> +	return true;
> +}
> +
> +static unsigned long
> +drm_gem_shmem_shrinker_scan_objects(struct shrinker *shrinker,
> +				    struct shrink_control *sc)
> +{
> +	struct drm_gem_shmem_shrinker *shmem_shrinker = shrinker->private_data;
> +	unsigned long nr_to_scan = sc->nr_to_scan;
> +	unsigned long remaining = 0;
> +	unsigned long freed = 0;
> +
> +	/* purge as many objects as we can */
> +	freed += drm_gem_lru_scan(&shmem_shrinker->lru_evictable,
> +				  nr_to_scan, &remaining,
> +				  drm_gem_shmem_shrinker_purge_locked);
> +
> +	/* evict as many objects as we can */
> +	if (freed < nr_to_scan)
> +		freed += drm_gem_lru_scan(&shmem_shrinker->lru_evictable,
> +					  nr_to_scan - freed, &remaining,
> +					  drm_gem_shmem_shrinker_evict_locked);
> +
> +	return (freed > 0 && remaining > 0) ? freed : SHRINK_STOP;
> +}
> +
> +static int drm_gem_shmem_shrinker_init(struct drm_gem_shmem *shmem_mm,
> +				       const char *shrinker_name)
> +{
> +	struct drm_gem_shmem_shrinker *shmem_shrinker = &shmem_mm->shrinker;
> +	struct shrinker *shrinker;
> +
> +	shrinker = shrinker_alloc(0, shrinker_name);
> +	if (!shrinker)
> +		return -ENOMEM;
> +
> +	shrinker->count_objects = drm_gem_shmem_shrinker_count_objects;
> +	shrinker->scan_objects = drm_gem_shmem_shrinker_scan_objects;
> +	shrinker->private_data = shmem_shrinker;
> +	shrinker->seeks = DEFAULT_SEEKS;
> +
> +	mutex_init(&shmem_shrinker->lock);
> +	shmem_shrinker->shrinker = shrinker;
> +	drm_gem_lru_init(&shmem_shrinker->lru_evictable, &shmem_shrinker->lock);
> +	drm_gem_lru_init(&shmem_shrinker->lru_evicted, &shmem_shrinker->lock);
> +	drm_gem_lru_init(&shmem_shrinker->lru_pinned, &shmem_shrinker->lock);
> +
> +	shrinker_register(shrinker);
> +
> +	return 0;
> +}
> +
> +static void drm_gem_shmem_shrinker_release(struct drm_device *dev,
> +					   struct drm_gem_shmem *shmem_mm)
> +{
> +	struct drm_gem_shmem_shrinker *shmem_shrinker = &shmem_mm->shrinker;
> +
> +	shrinker_free(shmem_shrinker->shrinker);
> +	drm_WARN_ON(dev, !list_empty(&shmem_shrinker->lru_evictable.list));
> +	drm_WARN_ON(dev, !list_empty(&shmem_shrinker->lru_evicted.list));
> +	drm_WARN_ON(dev, !list_empty(&shmem_shrinker->lru_pinned.list));
> +	mutex_destroy(&shmem_shrinker->lock);
> +}
> +
> +static int drm_gem_shmem_init(struct drm_device *dev)
> +{
> +	int err;
> +
> +	if (drm_WARN_ON(dev, dev->shmem_mm))
> +		return -EBUSY;
> +
> +	dev->shmem_mm = kzalloc(sizeof(*dev->shmem_mm), GFP_KERNEL);
> +	if (!dev->shmem_mm)
> +		return -ENOMEM;
> +
> +	err = drm_gem_shmem_shrinker_init(dev->shmem_mm, dev->unique);
> +	if (err)
> +		goto free_gem_shmem;
> +
> +	return 0;
> +
> +free_gem_shmem:
> +	kfree(dev->shmem_mm);
> +	dev->shmem_mm = NULL;
> +
> +	return err;
> +}
> +
> +static void drm_gem_shmem_release(struct drm_device *dev, void *ptr)
> +{
> +	struct drm_gem_shmem *shmem_mm = dev->shmem_mm;
> +
> +	drm_gem_shmem_shrinker_release(dev, shmem_mm);
> +	dev->shmem_mm = NULL;
> +	kfree(shmem_mm);
> +}
> +
> +/**
> + * drmm_gem_shmem_init() - Initialize drm-shmem internals
> + * @dev: DRM device
> + *
> + * Cleanup is automatically managed as part of DRM device releasing.
> + * Calling this function multiple times will result in a error.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +int drmm_gem_shmem_init(struct drm_device *dev)
> +{
> +	int err;
> +
> +	err = drm_gem_shmem_init(dev);
> +	if (err)
> +		return err;
> +
> +	err = drmm_add_action_or_reset(dev, drm_gem_shmem_release, NULL);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(drmm_gem_shmem_init);
> +
>   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.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 7edfc12f7c1f..8c26b7e41b95 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -99,8 +99,7 @@ static void panfrost_gem_mapping_release(struct kref *kref)
>   	 * time, and heap BOs may have acquired pages if the fault handler
>   	 * was called, in which case bo->sgts should be non-NULL.
>   	 */
> -	if (!bo->base.base.import_attach && (!bo->is_heap || bo->sgts) &&
> -	    bo->base.madv >= 0) {
> +	if (!bo->base.base.import_attach && (!bo->is_heap || bo->sgts)) {
>   		drm_gem_shmem_put_pages(&bo->base);
>   		bo->sgts = NULL;
>   	}
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> index d4fb0854cf2f..7b4deba803ed 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) &&
> +		!refcount_read(&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)
>   {
> @@ -26,7 +33,7 @@ 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;
>   	}
>   
> @@ -53,7 +60,7 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj)
>   	/* BO might have become unpurgeable if the last pages_use_count ref
>   	 * was dropped, but the BO hasn't been destroyed yet.
>   	 */
> -	if (!drm_gem_shmem_is_purgeable(shmem))
> +	if (!panfrost_gem_shmem_is_purgeable(shmem))
>   		goto unlock_mappings;
>   
>   	panfrost_gem_teardown_mappings_locked(bo);
> @@ -80,7 +87,7 @@ panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
>   	list_for_each_entry_safe(shmem, tmp, &pfdev->shrinker_list, madv_list) {
>   		if (freed >= sc->nr_to_scan)
>   			break;
> -		if (drm_gem_shmem_is_purgeable(shmem) &&
> +		if (panfrost_gem_shmem_is_purgeable(shmem) &&
>   		    panfrost_gem_purge(&shmem->base)) {
>   			freed += shmem->base.size >> PAGE_SHIFT;
>   			list_del_init(&shmem->madv_list);
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index 63767cf24371..6e729e716505 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -15,6 +15,7 @@ struct drm_vblank_crtc;
>   struct drm_vma_offset_manager;
>   struct drm_vram_mm;
>   struct drm_fb_helper;
> +struct drm_gem_shmem_shrinker;
>   
>   struct inode;
>   
> @@ -289,8 +290,13 @@ struct drm_device {
>   	/** @vma_offset_manager: GEM information */
>   	struct drm_vma_offset_manager *vma_offset_manager;
>   
> -	/** @vram_mm: VRAM MM memory manager */
> -	struct drm_vram_mm *vram_mm;
> +	union {
> +		/** @vram_mm: VRAM MM memory manager */
> +		struct drm_vram_mm *vram_mm;
> +
> +		/** @shmem_mm: SHMEM GEM memory manager */
> +		struct drm_gem_shmem *shmem_mm;
> +	};
>   
>   	/**
>   	 * @switch_power_state:
> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
> index 525480488451..df97c11fc99a 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>
> @@ -13,6 +14,7 @@
>   #include <drm/drm_prime.h>
>   
>   struct dma_buf_attachment;
> +struct drm_device;
>   struct drm_mode_create_dumb;
>   struct drm_printer;
>   struct sg_table;
> @@ -54,8 +56,8 @@ struct drm_gem_shmem_object {
>   	 * @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;
>   
> @@ -102,6 +104,14 @@ struct drm_gem_shmem_object {
>   	 * @map_wc: map object write-combined (instead of using shmem defaults).
>   	 */
>   	bool map_wc : 1;
> +
> +	/**
> +	 * @evicted: True if shmem pages are evicted by the memory shrinker.
> +	 * Used internally by memory shrinker. The evicted pages can be
> +	 * moved back to memory using drm_gem_shmem_swapin_locked(), unlike
> +	 * the purged pages (madv < 0) that are destroyed permanently.
> +	 */
> +	bool evicted : 1;
>   };
>   
>   #define to_drm_gem_shmem_obj(obj) \
> @@ -122,14 +132,19 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
>   int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma);
>   
>   int drm_gem_shmem_madvise_locked(struct drm_gem_shmem_object *shmem, int madv);
> +int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv);
>   
>   static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
>   {
> -	return (shmem->madv > 0) &&
> -		!refcount_read(&shmem->pages_pin_count) && shmem->sgt &&
> +	return (shmem->madv > 0) && shmem->base.funcs->evict &&
> +		refcount_read(&shmem->pages_use_count) &&
> +		!refcount_read(&shmem->pages_pin_count) &&
>   		!shmem->base.dma_buf && !shmem->base.import_attach;
>   }
>   
> +int drm_gem_shmem_swapin_locked(struct drm_gem_shmem_object *shmem);
> +
> +void drm_gem_shmem_evict_locked(struct drm_gem_shmem_object *shmem);
>   void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem);
>   
>   struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem);
> @@ -273,6 +288,53 @@ static inline int drm_gem_shmem_object_mmap(struct drm_gem_object *obj, struct v
>   	return drm_gem_shmem_mmap(shmem, vma);
>   }
>   
> +/**
> + * drm_gem_shmem_object_madvise - unlocked GEM object function for drm_gem_shmem_madvise_locked()
> + * @obj: GEM object
> + * @madv: Madvise value
> + *
> + * This function wraps drm_gem_shmem_madvise_locked(), providing unlocked variant.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +static inline int drm_gem_shmem_object_madvise(struct drm_gem_object *obj, int madv)
> +{
> +	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> +	return drm_gem_shmem_madvise(shmem, madv);
> +}
> +
> +/**
> + * struct drm_gem_shmem_shrinker - Memory shrinker of GEM shmem memory manager
> + */
> +struct drm_gem_shmem_shrinker {
> +	/** @lock: Protects @lru_* */
> +	struct mutex lock;
> +
> +	/** @shrinker: Shrinker for purging shmem GEM objects */
> +	struct shrinker *shrinker;
> +
> +	/** @lru_pinned: List of pinned shmem GEM objects */
> +	struct drm_gem_lru lru_pinned;
> +
> +	/** @lru_evictable: List of shmem GEM objects to be evicted */
> +	struct drm_gem_lru lru_evictable;
> +
> +	/** @lru_evicted: List of evicted shmem GEM objects */
> +	struct drm_gem_lru lru_evicted;
> +};
> +
> +/**
> + * struct drm_gem_shmem - GEM shmem memory manager
> + */
> +struct drm_gem_shmem {
> +	/** @shrinker: GEM shmem shrinker */
> +	struct drm_gem_shmem_shrinker shrinker;
> +};
> +
> +int drmm_gem_shmem_init(struct drm_device *dev);
> +
>   /*
>    * Driver ops
>    */

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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