mm/page_poison: expose page_poisoning_enabled to kernel modules

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>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/mm/page_poison.c b/mm/page_poison.c
index aa2b3d34e8eaa26018267314fe88568b382dbebc..830f60489b14b4dd0f15313201a34b0e41dbe65d 100644 (file)
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -17,6 +17,11 @@ static int __init early_page_poison_param(char *buf)
 }
 early_param("page_poison", early_page_poison_param);
 
+/**
+ * page_poisoning_enabled - check if page poisoning is enabled
+ *
+ * Return true if page poisoning is enabled, or false if not.
+ */
 bool page_poisoning_enabled(void)
 {
        /*
@@ -29,6 +34,7 @@ bool page_poisoning_enabled(void)
                (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
                debug_pagealloc_enabled()));
 }
+EXPORT_SYMBOL_GPL(page_poisoning_enabled);
 
 static void poison_page(struct page *page)
 {