[PATCH v27 3/4] mm/page_poison: expose page_poisoning_enabled to kernel modules

[Wei Wang <wei.w.wang@intel.com>]

In some usages, e.g. virtio-balloon, a kernel module needs to know if
page poisoning is in use. This patch exposes the page_poisoning_enabled
function to kernel modules.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
---
 mm/page_poison.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/page_poison.c b/mm/page_poison.c
index e83fd44..c08d02a 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -30,6 +30,11 @@ bool page_poisoning_enabled(void)
 		debug_pagealloc_enabled()));
 }
 
+/**
+ * page_poisoning_enabled - check if page poisoning is enabled
+ *
+ * Return true if page poisoning is enabled, or false if not.
+ */
 static void poison_page(struct page *page)
 {
 	void *addr = kmap_atomic(page);
@@ -37,6 +42,7 @@ static void poison_page(struct page *page)
 	memset(addr, PAGE_POISON, PAGE_SIZE);
 	kunmap_atomic(addr);
 }
+EXPORT_SYMBOL_GPL(page_poisoning_enabled);
 
 static void poison_pages(struct page *page, int n)
 {
-- 
2.7.4