From b21e700aa440536db9d2f41428c1e6c310b032f3 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Sat, 25 Mar 2023 08:18:05 +0000
Subject: [PATCH] Revert "Revert "drm/msm/gem: Prevent blocking within shrinker
 loop""

This reverts commit eb1f5e465641d330b4574cb7623e8f3151949909.

It was perserving the ABI, but that is not needed anymore at this point
in time.

Change-Id: I2f1ddf6bb64c0b7bc4a6b653d60cdd256820080d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
---
 drivers/gpu/drm/drm_gem.c              |  9 +++++++--
 drivers/gpu/drm/msm/msm_gem_shrinker.c | 11 +++++++++--
 include/drm/drm_gem.h                  |  4 +++-
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 8b68a3c1e6ab..b87ed4238fc8 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1351,10 +1351,13 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail);
  *
  * @lru: The LRU to scan
  * @nr_to_scan: The number of pages to try to reclaim
+ * @remaining: The number of pages left to reclaim, should be initialized by caller
  * @shrink: Callback to try to shrink/reclaim the object.
  */
 unsigned long
-drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan,
+drm_gem_lru_scan(struct drm_gem_lru *lru,
+		 unsigned int nr_to_scan,
+		 unsigned long *remaining,
 		 bool (*shrink)(struct drm_gem_object *obj))
 {
 	struct drm_gem_lru still_in_lru;
@@ -1393,8 +1396,10 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan,
 		 * hit shrinker in response to trying to get backing pages
 		 * for this obj (ie. while it's lock is already held)
 		 */
-		if (!dma_resv_trylock(obj->resv))
+		if (!dma_resv_trylock(obj->resv)) {
+			*remaining += obj->size >> PAGE_SHIFT;
 			goto tail;
+		}
 
 		if (shrink(obj)) {
 			freed += obj->size >> PAGE_SHIFT;
diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
index 1de14e67f96b..31f054c903a4 100644
--- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
+++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
@@ -107,6 +107,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 		bool (*shrink)(struct drm_gem_object *obj);
 		bool cond;
 		unsigned long freed;
+		unsigned long remaining;
 	} stages[] = {
 		/* Stages of progressively more aggressive/expensive reclaim: */
 		{ &priv->lru.dontneed, purge,        true },
@@ -116,14 +117,18 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 	};
 	long nr = sc->nr_to_scan;
 	unsigned long freed = 0;
+	unsigned long remaining = 0;
 
 	for (unsigned i = 0; (nr > 0) && (i < ARRAY_SIZE(stages)); i++) {
 		if (!stages[i].cond)
 			continue;
 		stages[i].freed =
-			drm_gem_lru_scan(stages[i].lru, nr, stages[i].shrink);
+			drm_gem_lru_scan(stages[i].lru, nr,
+					&stages[i].remaining,
+					 stages[i].shrink);
 		nr -= stages[i].freed;
 		freed += stages[i].freed;
+		remaining += stages[i].remaining;
 	}
 
 	if (freed) {
@@ -132,7 +137,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 				     stages[3].freed);
 	}
 
-	return (freed > 0) ? freed : SHRINK_STOP;
+	return (freed > 0 && remaining > 0) ? freed : SHRINK_STOP;
 }
 
 #ifdef CONFIG_DEBUG_FS
@@ -182,10 +187,12 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 		NULL,
 	};
 	unsigned idx, unmapped = 0;
+	unsigned long remaining = 0;
 
 	for (idx = 0; lrus[idx] && unmapped < vmap_shrink_limit; idx++) {
 		unmapped += drm_gem_lru_scan(lrus[idx],
 					     vmap_shrink_limit - unmapped,
+					     &remaining,
 					     vmap_shrink);
 	}
 
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index bd42f25e449c..60b2dda8d964 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -472,7 +472,9 @@ int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
 void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock);
 void drm_gem_lru_remove(struct drm_gem_object *obj);
 void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj);
-unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan,
+unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru,
+			       unsigned int nr_to_scan,
+			       unsigned long *remaining,
 			       bool (*shrink)(struct drm_gem_object *obj));
 
 #endif /* __DRM_GEM_H__ */