This is a note to let you know that I've just added the patch titled
media: vb2: frame_vector.c: replace WARN_ONCE with a comment
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-vb2-frame_vector.c-replace-warn_once-with-a-co.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6cc933c2b98978a3fd9b27b6dee0f7738a855a94
Author: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Date: Thu Aug 17 12:41:32 2023 +0200
media: vb2: frame_vector.c: replace WARN_ONCE with a comment
[ Upstream commit 735de5caf79e06cc9fb96b1b4f4974674ae3e917 ]
The WARN_ONCE was issued also in cases that had nothing to do with VM_IO
(e.g. if the start address was just a random value and uaccess fails with
-EFAULT).
There are no reports of WARN_ONCE being issued for actual VM_IO cases, so
just drop it and instead add a note to the comment before the function.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reported-by: Yikebaer Aizezi <yikebaer61@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 0e589a9a88012..1cd81d38ad2d0 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -29,6 +29,10 @@
* different type underlying the specified range of virtual addresses.
* When the function isn't able to map a single page, it returns error.
*
+ * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used
+ * to be able to do that, but that could (racily) return non-refcounted
+ * pfns.
+ *
* This function takes care of grabbing mmap_lock as necessary.
*/
int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
@@ -77,8 +81,6 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
goto out;
}
- /* This used to (racily) return non-refcounted pfns. Let people know */
- WARN_ONCE(1, "get_vaddr_frames() cannot follow VM_IO mapping");
vec->nr_frames = 0;
out:
