[PATCH v2] drm/ttm: Fix GPU MM stats during pool shrinking

[Matthew Brost <matthew.brost@intel.com>]

TTM pool shrinking frees pages by calling __free_pages() directly,
which bypasses updates to NR_GPU_ACTIVE and leaves GPU MM accounting
out of sync.

Introduce a helper, __free_pages_gpu_account(), and use it for all page
frees in ttm_pool.c so GPU MM statistics are updated consistently.

Reported-by: Kenneth Crudup <kenny@panix.com>
Fixes: ae80122f3896 ("drm/ttm: use gpu mm stats to track gpu memory allocations. (v4)")
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Matthew Brost <matthew.brost@intel.com>

---

v2:
 - Replace put_page() with __free_pages_gpu_account() (Kenneth)
---
 drivers/gpu/drm/ttm/ttm_pool.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index 26a3689e5fd9..278bbe7a11ad 100644
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -206,6 +206,14 @@ static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
 	return NULL;
 }
 
+static void __free_pages_gpu_account(struct page *p, unsigned int order,
+				     bool reclaim)
+{
+	mod_lruvec_page_state(p, reclaim ? NR_GPU_RECLAIM : NR_GPU_ACTIVE,
+			      -(1 << order));
+	__free_pages(p, order);
+}
+
 /* Reset the caching and pages of size 1 << order */
 static void ttm_pool_free_page(struct ttm_pool *pool, enum ttm_caching caching,
 			       unsigned int order, struct page *p, bool reclaim)
@@ -223,9 +231,7 @@ static void ttm_pool_free_page(struct ttm_pool *pool, enum ttm_caching caching,
 #endif
 
 	if (!pool || !ttm_pool_uses_dma_alloc(pool)) {
-		mod_lruvec_page_state(p, reclaim ? NR_GPU_RECLAIM : NR_GPU_ACTIVE,
-				      -(1 << order));
-		__free_pages(p, order);
+		__free_pages_gpu_account(p, order, reclaim);
 		return;
 	}
 
@@ -606,7 +612,7 @@ static int ttm_pool_restore_commit(struct ttm_pool_tt_restore *restore,
 			 */
 			ttm_pool_split_for_swap(restore->pool, p);
 			copy_highpage(restore->alloced_page + i, p);
-			__free_pages(p, 0);
+			__free_pages_gpu_account(p, 0, false);
 		}
 
 		restore->restored_pages++;
@@ -1068,7 +1074,7 @@ long ttm_pool_backup(struct ttm_pool *pool, struct ttm_tt *tt,
 			if (flags->purge) {
 				shrunken += num_pages;
 				page->private = 0;
-				__free_pages(page, order);
+				__free_pages_gpu_account(page, order, false);
 				memset(tt->pages + i, 0,
 				       num_pages * sizeof(*tt->pages));
 			}
@@ -1109,7 +1115,7 @@ long ttm_pool_backup(struct ttm_pool *pool, struct ttm_tt *tt,
 		}
 		handle = shandle;
 		tt->pages[i] = ttm_backup_handle_to_page_ptr(handle);
-		put_page(page);
+		__free_pages_gpu_account(page, 0, false);
 		shrunken++;
 	}
 
-- 
2.34.1