| From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com> |
| 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@gmail.com |
| Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> |
| Reported-by: Matthew Wilcox <willy@infradead.org> |
| Reviewed-by: Baoquan He <bhe@redhat.com> |
| Reviewed-by: Ira Weiny <ira.weiny@intel.com> |
| Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| 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) |
| { |
| _ |
