linux-kernel - [PATCH] tee: shm: fix slab page refcounting

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Message-Id: <20250325195021.3589797-1-m.felsch@pengutronix.de>
Date: Tue, 25 Mar 2025 20:50:20 +0100
From: Marco Felsch <m.felsch@...gutronix.de>
To: jens.wiklander@...aro.org,
	sumit.garg@...nel.org,
	akpm@...ux-foundation.org,
	vbabka@...e.cz,
	willy@...radead.org
Cc: kernel@...gutronix.de,
	op-tee@...ts.trustedfirmware.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] tee: shm: fix slab page refcounting

Skip manipulating the refcount in case of slab pages according commit
b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page").

Fixes: b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page")
Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
---
 drivers/tee/tee_shm.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index daf6e5cfd59a..3d6a3077b6f2 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -19,16 +19,24 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
 {
 	size_t n;
 
-	for (n = 0; n < page_count; n++)
-		put_page(pages[n]);
+	for (n = 0; n < page_count; n++) {
+		struct page *page = pages[n];
+
+		if (!PageSlab(page))
+			put_page(pages[n]);
+	}
 }
 
 static void shm_get_kernel_pages(struct page **pages, size_t page_count)
 {
 	size_t n;
 
-	for (n = 0; n < page_count; n++)
-		get_page(pages[n]);
+	for (n = 0; n < page_count; n++) {
+		struct page *page = pages[n];
+
+		if (!PageSlab(page))
+			get_page(pages[n]);
+	}
 }
 
 static void release_registered_pages(struct tee_shm *shm)
-- 
2.39.5