[PATCH v12 3/6] mm/hwpoison: return -EFAULT when copy fail in copy_mc_[user]_highpage()

Tong Tiangen
2024-05-28T08:59:32Z

If hardware errors are encountered during page copying, returning the bytes
not copied is not meaningful, and the caller cannot do any processing on
the remaining data. Returning -EFAULT is more reasonable, which represents
a hardware error encountered during the copying.

Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
---
include/linux/highmem.h | 8 ++++----
mm/khugepaged.c | 4 ++--
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 00341b56d291..64a567d5ad6f 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -335,8 +335,8 @@ static inline void copy_highpage(struct page *to, struct page *from)
/*
* If architecture supports machine check exception handling, define the
* #MC versions of copy_user_highpage and copy_highpage. They copy a memory
- * page with #MC in source page (@from) handled, and return the number
- * of bytes not copied if there was a #MC, otherwise 0 for success.
+ * page with #MC in source page (@from) handled, and return -EFAULT if there
+ * was a #MC, otherwise 0 for success.
*/
static inline int copy_mc_user_highpage(struct page *to, struct page *from,
unsigned long vaddr, struct vm_area_struct *vma)
@@ -352,7 +352,7 @@ static inline int copy_mc_user_highpage(struct page *to, struct page *from,
kunmap_local(vto);
kunmap_local(vfrom);

- return ret;
+ return ret ? -EFAULT : 0;
}

static inline int copy_mc_highpage(struct page *to, struct page *from)
@@ -368,7 +368,7 @@ static inline int copy_mc_highpage(struct page *to, struct page *from)
kunmap_local(vto);
kunmap_local(vfrom);

- return ret;
+ return ret ? -EFAULT : 0;
}
#else
static inline int copy_mc_user_highpage(struct page *to, struct page *from,
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 774a97e6e2da..cce838e85967 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -798,7 +798,7 @@ static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio,
continue;
}
src_page = pte_page(pteval);
- if (copy_mc_user_highpage(page, src_page, src_addr, vma) > 0) {
+ if (copy_mc_user_highpage(page, src_page, src_addr, vma)) {
result = SCAN_COPY_MC;
break;
}
@@ -2042,7 +2042,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
index++;
dst++;
}
- if (copy_mc_highpage(dst, folio_page(folio, 0)) > 0) {
+ if (copy_mc_highpage(dst, folio_page(folio, 0))) {
result = SCAN_COPY_MC;
goto rollback;
}
--
2.25.1