diff mbox series

[v18,19/26] drm/shmem-helper: Add common memory shrinker

Message ID 20231029230205.93277-20-dmitry.osipenko@collabora.com (mailing list archive)
State New, archived
Headers show
Series Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers | expand

Commit Message

Dmitry Osipenko Oct. 29, 2023, 11:01 p.m. UTC
Introduce common drm-shmem shrinker for DRM drivers.

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@collabora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c        | 386 +++++++++++++++++-
 .../gpu/drm/panfrost/panfrost_gem_shrinker.c  |   9 +-
 include/drm/drm_device.h                      |  10 +-
 include/drm/drm_gem_shmem_helper.h            |  68 ++-
 4 files changed, 450 insertions(+), 23 deletions(-)

Comments

Boris Brezillon Nov. 10, 2023, 2:58 p.m. UTC | #1
On Mon, 30 Oct 2023 02:01:58 +0300
Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:

> @@ -238,6 +308,20 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
>  	if (refcount_dec_not_one(&shmem->pages_use_count))
>  		return;
>  
> +	/*
> +	 * Destroying the object is a special case because acquiring
> +	 * the obj lock can cause a locking order inversion between
> +	 * reservation_ww_class_mutex and fs_reclaim.
> +	 *
> +	 * This deadlock is not actually possible, because no one should
> +	 * be already holding the lock when GEM is released.  Unfortunately
> +	 * lockdep is not aware of this detail.  So when the refcount drops
> +	 * to zero, we pretend it is already locked.
> +	 */
> +	if (!kref_read(&shmem->base.refcount) &&
> +	    refcount_dec_and_test(&shmem->pages_use_count))
> +		return drm_gem_shmem_free_pages(shmem);

Uh, with get/put_pages() being moved to the create/free_gem()
hooks, we're back to a situation where pages_use_count > 0 when we
reach gem->refcount == 0, which is not nice. We really need to patch
drivers so they dissociate GEM creation from the backing storage
allocation/reservation + mapping of the BO in GPU VM space.
Boris Brezillon Nov. 13, 2023, 9:35 a.m. UTC | #2
On Fri, 10 Nov 2023 15:58:58 +0100
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> On Mon, 30 Oct 2023 02:01:58 +0300
> Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:
> 
> > @@ -238,6 +308,20 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> >  	if (refcount_dec_not_one(&shmem->pages_use_count))
> >  		return;
> >  
> > +	/*
> > +	 * Destroying the object is a special case because acquiring
> > +	 * the obj lock can cause a locking order inversion between
> > +	 * reservation_ww_class_mutex and fs_reclaim.
> > +	 *
> > +	 * This deadlock is not actually possible, because no one should
> > +	 * be already holding the lock when GEM is released.  Unfortunately
> > +	 * lockdep is not aware of this detail.  So when the refcount drops
> > +	 * to zero, we pretend it is already locked.
> > +	 */
> > +	if (!kref_read(&shmem->base.refcount) &&
> > +	    refcount_dec_and_test(&shmem->pages_use_count))
> > +		return drm_gem_shmem_free_pages(shmem);  
> 
> Uh, with get/put_pages() being moved to the create/free_gem()
> hooks, we're back to a situation where pages_use_count > 0 when we
> reach gem->refcount == 0, which is not nice. We really need to patch
> drivers so they dissociate GEM creation from the backing storage
> allocation/reservation + mapping of the BO in GPU VM space.

I gave this a try, and I think it'd work fine for lima (I have patches
if you want) and panfrost (I have patches for panfrost too, basically
addressing my comments on patch 15). It's a bit trickier for v3d, but
still possible (we'd have to add a gpu_map_count to v3d_bo, get it
incremented for each BO referenced by a job when the job is created,
decremented for each BO referenced by a job when the job is destroyed,
and have a _put_pages() call when gpu_map_count reached zero). The main
problem is virtio, where BO backing storage lifetime is really tied to
the BO object lifetime, and my virtio knowledge is too limited to come
up with an solution to dissociate those 2 things.

TLDR; let's just keep this hack for now. This being said, there are 2
things that I think should be addressed:

1/ we want this change in patch 18 ("drm/shmem-helper: Change sgt
allocation policy") to keep this series bisectable, otherwise you'll
hit the WARN_ON(shmem->pages_use_count != 0) in drm_gem_shmem_free()

2/ we should do:

	if (!kref_read(&shmem->base.refcount) {
		if (refcount_dec_and_test(&shmem->pages_use_count))
			drm_gem_shmem_free_pages(shmem);

		return;
	}

  if we don't want to try to acquire the resv lock when the user leaked
  a pages ref (the core will complain about this leak in
  drm_gem_shmem_free() anyway)

Regards,

Boris
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 1420d2166b76..007521bea302 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>
 
@@ -88,8 +89,6 @@  __drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
 	if (ret)
 		goto err_release;
 
-	INIT_LIST_HEAD(&shmem->madv_list);
-
 	if (!private) {
 		/*
 		 * Our buffers are kept pinned, so allocating them
@@ -128,11 +127,49 @@  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 +212,25 @@  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;
 
+	drm_WARN_ON(obj->dev, obj->import_attach);
+
 	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 +251,29 @@  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 +290,8 @@  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);
 
@@ -238,6 +308,20 @@  void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
 	if (refcount_dec_not_one(&shmem->pages_use_count))
 		return;
 
+	/*
+	 * Destroying the object is a special case because acquiring
+	 * the obj lock can cause a locking order inversion between
+	 * reservation_ww_class_mutex and fs_reclaim.
+	 *
+	 * This deadlock is not actually possible, because no one should
+	 * be already holding the lock when GEM is released.  Unfortunately
+	 * lockdep is not aware of this detail.  So when the refcount drops
+	 * to zero, we pretend it is already locked.
+	 */
+	if (!kref_read(&shmem->base.refcount) &&
+	    refcount_dec_and_test(&shmem->pages_use_count))
+		return drm_gem_shmem_free_pages(shmem);
+
 	dma_resv_lock(shmem->base.resv, NULL);
 	drm_gem_shmem_put_pages_locked(shmem);
 	dma_resv_unlock(shmem->base.resv);
@@ -250,6 +334,11 @@  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)
 {
@@ -275,6 +364,10 @@  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);
@@ -473,29 +566,50 @@  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;
+	int ret;
+
+	ret = dma_resv_lock_interruptible(obj->resv, NULL);
+	if (ret)
+		return ret;
+
+	ret = drm_gem_shmem_madvise_locked(shmem, madv);
+	dma_resv_unlock(obj->resv);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_madvise);
+
+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;
 
 	dma_resv_assert_held(shmem->base.resv);
 
-	drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
+	if (shmem->evicted)
+		return;
 
-	dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
-	sg_free_table(shmem->sgt);
-	kfree(shmem->sgt);
-	shmem->sgt = NULL;
+	drm_gem_shmem_free_pages(shmem);
+	drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
+}
 
-	drm_gem_shmem_put_pages_locked(shmem);
+void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
+{
+	struct drm_gem_object *obj = &shmem->base;
 
-	shmem->madv = -1;
+	drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
 
-	drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
+	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
@@ -506,9 +620,45 @@  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
@@ -555,22 +705,32 @@  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;
@@ -593,6 +753,7 @@  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);
@@ -678,7 +839,9 @@  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);
 
@@ -765,8 +928,12 @@  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;
+
+	drm_WARN_ON(obj->dev, drm_gem_shmem_is_evictable(shmem));
+	drm_WARN_ON(obj->dev, drm_gem_shmem_is_purgeable(shmem));
 
 	ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
 	if (ret)
@@ -813,6 +980,191 @@  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_gem_shmem_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 *shmem_shrinker =
+					to_drm_gem_shmem_shrinker(shrinker);
+	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;
+	unsigned long nr_to_scan = sc->nr_to_scan;
+	unsigned long remaining = 0;
+	unsigned long freed = 0;
+
+	shmem_shrinker = to_drm_gem_shmem_shrinker(shrinker);
+
+	/* 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;
+	int err;
+
+	shmem_shrinker->base.count_objects = drm_gem_shmem_shrinker_count_objects;
+	shmem_shrinker->base.scan_objects = drm_gem_shmem_shrinker_scan_objects;
+	shmem_shrinker->base.seeks = DEFAULT_SEEKS;
+
+	mutex_init(&shmem_shrinker->lock);
+	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);
+
+	err = register_shrinker(&shmem_shrinker->base, shrinker_name);
+	if (err) {
+		mutex_destroy(&shmem_shrinker->lock);
+		return err;
+	}
+
+	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;
+
+	unregister_shrinker(&shmem_shrinker->base);
+	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_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
index 72193bd734e1..1aa94fff7072 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)
 {
@@ -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/include/drm/drm_device.h b/include/drm/drm_device.h
index c490977ee250..9ef31573057c 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;
 
@@ -290,8 +291,13 @@  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 6aad3e27d7ee..3bb70616d095 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 {
+	/** @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 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
  */