Catch page from ZONE_DEVICE in free_hot_cold_page(). This should never
happen as ZONE_DEVICE page must always have an elevated refcount.
This is safety-net to catch any refcounting issues in a sane way for any
ZONE_DEVICE pages.
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0fbfead..09b2630 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2435,6 +2435,16 @@ void free_hot_cold_page(struct page *page, bool cold)
unsigned long pfn = page_to_pfn(page);
int migratetype;
+ /*
+ * This should never happen ! Page from ZONE_DEVICE always must have an
+ * active refcount. Complain about it and try to restore the refcount.
+ */
+ if (is_zone_device_page(page)) {
+ VM_BUG_ON_PAGE(is_zone_device_page(page), page);
+ page_ref_inc(page);
+ return;
+ }
+
if (!free_pcp_prepare(page))
return;
--
2.4.3
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