[PATCH v4 2/6] mm: add folio_mc_copy()

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

Add a #MC variant of folio_copy() which uses copy_mc_highpage() to
support #MC handled during folio copy, it will be used in folio
migration soon.

Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
 include/linux/mm.h |  1 +
 mm/util.c          | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c499d5adb748..cc21b2f0cdf8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1321,6 +1321,7 @@ 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 c9e519e6811f..90ea0c0f10d3 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -828,6 +828,23 @@ 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;
+
+	for (;;) {
+		if (copy_mc_highpage(folio_page(dst, i), folio_page(src, i)))
+			return -EHWPOISON;
+		if (++i == nr)
+			break;
+		cond_resched();
+	}
+
+	return 0;
+}
+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