The patch titled
Subject: mm/highmem: delete memmove_page()
has been added to the -mm mm-unstable branch. Its filename is
mm-highmem-delete-memmove_page.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-highmem-delete-memmove_page.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Fabio M. De Francesco" <fmdefrancesco@xxxxxxxxx>
Subject: mm/highmem: delete memmove_page()
Date: Mon, 6 Jun 2022 16:15:33 +0200
Matthew Wilcox reported that, while he was looking at memmove_page(), he
realized that it can't actually work.
The reasons are hidden in its implementation, which makes use of memmove()
on logical addresses provided by kmap_local_page(). memmove() does the
wrong thing when it tests "if (dest <= src)".
Therefore, delete memmove_page().
No need to change any other code because we have no call sites of
memmove_page() across the whole kernel.
Link: https://lkml.kernel.org/r/20220606141533.555-1-fmdefrancesco@xxxxxxxxx
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
Reported-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Reviewed-by: Baoquan He <bhe@xxxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/highmem.h | 13 -------------
1 file changed, 13 deletions(-)
--- a/include/linux/highmem.h~mm-highmem-delete-memmove_page
+++ a/include/linux/highmem.h
@@ -347,19 +347,6 @@ static inline void memcpy_page(struct pa
kunmap_local(dst);
}
-static inline void memmove_page(struct page *dst_page, size_t dst_off,
- struct page *src_page, size_t src_off,
- size_t len)
-{
- char *dst = kmap_local_page(dst_page);
- char *src = kmap_local_page(src_page);
-
- VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);
- memmove(dst + dst_off, src + src_off, len);
- kunmap_local(src);
- kunmap_local(dst);
-}
-
static inline void memset_page(struct page *page, size_t offset, int val,
size_t len)
{
_
Patches currently in -mm which might be from fmdefrancesco@xxxxxxxxx are
mm-highmem-delete-memmove_page.patch
