1 files changed, 33 insertions, 22 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6e0b4596cde9..3e7bbb5dae41 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -378,25 +378,9 @@ int page_group_by_mobility_disabled __read_mostly;
  */
 static DEFINE_STATIC_KEY_TRUE(deferred_pages);
 
-/*
- * Calling kasan_poison_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 bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
+static inline bool deferred_pages_enabled(void)
 {
-	return static_branch_unlikely(&deferred_pages) ||
-	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
-	       PageSkipKASanPoison(page);
+	return static_branch_unlikely(&deferred_pages);
 }
 
 /* Returns true if the struct page for the pfn is uninitialised */
@@ -447,11 +431,9 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	return false;
 }
 #else
-static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
+static inline bool deferred_pages_enabled(void)
 {
-	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
-	       PageSkipKASanPoison(page);
+	return false;
 }
 
 static inline bool early_page_uninitialised(unsigned long pfn)
@@ -1267,6 +1249,35 @@ out:
 	return ret;
 }
 
+/*
+ * Skip KASAN memory poisoning when either:
+ *
+ * 1. Deferred memory initialization has not yet completed,
+ *    see the explanation below.
+ * 2. Skipping poisoning is requested via FPI_SKIP_KASAN_POISON,
+ *    see the comment next to it.
+ * 3. Skipping poisoning is requested via __GFP_SKIP_KASAN_POISON,
+ *    see the comment next to it.
+ *
+ * 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 bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
+{
+	return deferred_pages_enabled() ||
+	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
+	       PageSkipKASanPoison(page);
+}
+
 static void kernel_init_free_pages(struct page *page, int numpages, bool zero_tags)
 {
 	int i;