The patch titled
Subject: highmem: memcpy_{from,to}_folio() fix
has been added to the -mm mm-unstable branch. Its filename is
highmem-add-memcpy_to_folio-and-memcpy_from_folio-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/highmem-add-memcpy_to_folio-and-memcpy_from_folio-fix.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: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Subject: highmem: memcpy_{from,to}_folio() fix
Date: Wed, 2 Aug 2023 16:43:54 +0200
memcpy_to_folio() and memcpy_from_folio() compute the size of the chunk
of memory they can copy for each page, but then they don't use the chunk
size in the actual memcpy. Fix that.
Also, git rid of superfluous parentheses in these two functions.
Link: https://lkml.kernel.org/r/20230802144354.1023099-1-agruenba@xxxxxxxxxx
Fixes: 520a10fe2d72 ("highmem: add memcpy_to_folio() and memcpy_from_folio()")
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/highmem.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/include/linux/highmem.h~highmem-add-memcpy_to_folio-and-memcpy_from_folio-fix
+++ a/include/linux/highmem.h
@@ -445,13 +445,13 @@ static inline void memcpy_from_folio(cha
VM_BUG_ON(offset + len > folio_size(folio));
do {
- char *from = kmap_local_folio(folio, offset);
+ const char *from = kmap_local_folio(folio, offset);
size_t chunk = len;
if (folio_test_highmem(folio) &&
- (chunk > (PAGE_SIZE - offset_in_page(offset))))
+ chunk > PAGE_SIZE - offset_in_page(offset))
chunk = PAGE_SIZE - offset_in_page(offset);
- memcpy(to, from, len);
+ memcpy(to, from, chunk);
kunmap_local(from);
from += chunk;
@@ -470,9 +470,9 @@ static inline void memcpy_to_folio(struc
size_t chunk = len;
if (folio_test_highmem(folio) &&
- (chunk > (PAGE_SIZE - offset_in_page(offset))))
+ chunk > PAGE_SIZE - offset_in_page(offset))
chunk = PAGE_SIZE - offset_in_page(offset);
- memcpy(to, from, len);
+ memcpy(to, from, chunk);
kunmap_local(to);
from += chunk;
_
Patches currently in -mm which might be from agruenba@xxxxxxxxxx are
highmem-add-memcpy_to_folio-and-memcpy_from_folio-fix.patch
