[PATCH rfc 5/9] mm: add folio_mc_copy()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Add a variant of folio_copy() which use copy_mc_highpage() to support
machine check safe copy when folio copy.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 include/linux/mm.h |  1 +
 mm/util.c          | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ac6b71cbdffb..fffa6025d8f9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1300,6 +1300,7 @@ void put_pages_list(struct list_head *pages);
 
 void split_page(struct page *page, unsigned int order);
 void folio_copy(struct folio *dst, struct folio *src);
+int folio_mc_copy(struct folio *dst, struct folio *src);
 
 unsigned long nr_free_buffer_pages(void);
 
diff --git a/mm/util.c b/mm/util.c
index 5faf3adc6f43..63e6e644eb5a 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -828,6 +828,26 @@ void folio_copy(struct folio *dst, struct folio *src)
 }
 EXPORT_SYMBOL(folio_copy);
 
+int folio_mc_copy(struct folio *dst, struct folio *src)
+{
+	long nr = folio_nr_pages(src);
+	long i = 0;
+	int ret = 0;
+
+	for (;;) {
+		if (copy_mc_highpage(folio_page(dst, i), folio_page(src, i))) {
+			ret = -EFAULT;
+			break;
+		}
+		if (++i == nr)
+			break;
+		cond_resched();
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(folio_mc_copy);
+
 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
 int sysctl_overcommit_ratio __read_mostly = 50;
 unsigned long sysctl_overcommit_kbytes __read_mostly;
-- 
2.27.0