1 files changed, 29 insertions, 8 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cd1c9d32ef9a..2cd1f9bb1b52 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -294,6 +294,32 @@ EXPORT_SYMBOL(nr_online_nodes);
 int page_group_by_mobility_disabled __read_mostly;
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+/*
+ * During boot we initialize deferred pages on-demand, as needed, but once
+ * page_alloc_init_late() has finished, the deferred pages are all initialized,
+ * and we can permanently disable that path.
+ */
+static DEFINE_STATIC_KEY_TRUE(deferred_pages);
+
+/*
+ * Calling kasan_free_pages() only after deferred memory initialization
+ * has completed. Poisoning pages during deferred memory init will greatly
+ * lengthen the process and cause problem in large memory systems as the
+ * deferred pages initialization is done with interrupt disabled.
+ *
+ * Assuming that there will be no reference to those newly initialized
+ * pages before they are ever allocated, this should have no effect on
+ * KASAN memory tracking as the poison will be properly inserted at page
+ * allocation time. The only corner case is when pages are allocated by
+ * on-demand allocation and then freed again before the deferred pages
+ * initialization is done, but this is not likely to happen.
+ */
+static inline void kasan_free_nondeferred_pages(struct page *page, int order)
+{
+        if (!static_branch_unlikely(&deferred_pages))
+                kasan_free_pages(page, order);
+}
+
 /* Returns true if the struct page for the pfn is uninitialised */
 static inline bool __meminit early_page_uninitialised(unsigned long pfn)
 {
@@ -340,6 +366,8 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
         return false;
 }
 #else
+#define kasan_free_nondeferred_pages(p, o)      kasan_free_pages(p, o)
+
 static inline bool early_page_uninitialised(unsigned long pfn)
 {
         return false;
@@ -1043,7 +1071,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
         arch_free_page(page, order);
         kernel_poison_pages(page, 1 << order, 0);
         kernel_map_pages(page, 1 << order, 0);
-        kasan_free_pages(page, order);
+        kasan_free_nondeferred_pages(page, order);
 
         return true;
 }
@@ -1613,13 +1641,6 @@ static int __init deferred_init_memmap(void *data)
 }
 
 /*
- * During boot we initialize deferred pages on-demand, as needed, but once
- * page_alloc_init_late() has finished, the deferred pages are all initialized,
- * and we can permanently disable that path.
- */
-static DEFINE_STATIC_KEY_TRUE(deferred_pages);
-
-/*
  * If this zone has deferred pages, try to grow it by initializing enough
  * deferred pages to satisfy the allocation specified by order, rounded up to
  * the nearest PAGES_PER_SECTION boundary.  So we're adding memory in increments