[PATCH -mmotm] mm: memory-failure: add stub for page_handle_poison()

[Randy Dunlap <rdunlap@xxxxxxxxxxxxx>]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Fix a build error when no HWPOISON kconfig symbols are set/enabled
by providing a stub function for 'page_handle_poison()'.

../mm/memory-failure.c: In function ‘__soft_offline_page’:
../mm/memory-failure.c:1827:3: error: implicit declaration of function ‘page_handle_poison’; did you mean ‘page_init_poison’? [-Werror=implicit-function-declaration]
   page_handle_poison(page, false, true);

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
---
 mm/memory-failure.c |    5 +++++
 1 file changed, 5 insertions(+)

--- mmotm-2020-0625-2036.orig/mm/memory-failure.c
+++ mmotm-2020-0625-2036/mm/memory-failure.c
@@ -200,6 +200,11 @@ int hwpoison_filter(struct page *p)
 {
 	return 0;
 }
+
+static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
+{
+	return true;
+}
 #endif
 
 EXPORT_SYMBOL_GPL(hwpoison_filter);