linux-kernel - [PATCH] gpu/drm: Use local kmap in drm_clflush

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Message-Id: <20251117153057.1800631-1-dave@stgolabs.net>
Date: Mon, 17 Nov 2025 07:30:57 -0800
From: Davidlohr Bueso <dave@...olabs.net>
To: maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	dave@...olabs.net
Subject: [PATCH] gpu/drm: Use local kmap in drm_clflush_page()

Replace the now deprecated kmap_atomic() with kmap_local_page().

Optimize for the non-highmem cases and avoid disabling preemption and
pagefaults as clflushopt does not require being CPU locality guarantees
and the mapping will hold valid across context switches. Further, highmem
is planned to to be removed[1].

[1] https://lore.kernel.org/all/4ff89b72-03ff-4447-9d21-dd6a5fe1550f@app.fastmail.com/
Signed-off-by: Davidlohr Bueso <dave@...olabs.net>
---
 drivers/gpu/drm/drm_cache.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index ea1d2d5d2c66..b6a309f827f8 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -57,10 +57,10 @@ drm_clflush_page(struct page *page)
 	if (unlikely(page == NULL))
 		return;
 
-	page_virtual = kmap_atomic(page);
+	page_virtual = kmap_local_page(page);
 	for (i = 0; i < PAGE_SIZE; i += size)
 		clflushopt(page_virtual + i);
-	kunmap_atomic(page_virtual);
+	kunmap_local(page_virtual);
 }
 
 static void drm_cache_flush_clflush(struct page *pages[],
-- 
2.39.5