On 9/16/19 5:57 PM, Andrey Ryabinin wrote:

quoted

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -710,8 +710,12 @@ static int __init early_debug_pagealloc(char *buf)
 	if (kstrtobool(buf, &enable))
 		return -EINVAL;
 
-	if (enable)
+	if (enable) {
 		static_branch_enable(&_debug_pagealloc_enabled);
+#ifdef CONFIG_PAGE_OWNER
+		page_owner_free_stack_disabled = false;

I think this won't work with CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y

Good point, thanks.

quoted

+#endif
+	}
 
 	return 0;
 }

diff --git a/mm/page_owner.c b/mm/page_owner.c
index dee931184788..b589bfbc4795 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c

@@ -24,13 +24,15 @@ struct page_owner {
 	short last_migrate_reason;
 	gfp_t gfp_mask;
 	depot_stack_handle_t handle;
-#ifdef CONFIG_DEBUG_PAGEALLOC
+#ifdef CONFIG_PAGE_OWNER_FREE_STACK
 	depot_stack_handle_t free_handle;
 #endif
 };
 
 static bool page_owner_disabled = true;
+bool page_owner_free_stack_disabled = true;
 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
+static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack);
 
 static depot_stack_handle_t dummy_handle;
 static depot_stack_handle_t failure_handle;

@@ -46,6 +48,9 @@ static int __init early_page_owner_param(char *buf)
 	if (strcmp(buf, "on") == 0)
 		page_owner_disabled = false;
 
+	if (!page_owner_disabled && IS_ENABLED(CONFIG_KASAN))

I'd rather keep all logic in one place, i.e. "if (!page_owner_disabled && (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled())"
With this no changes in early_debug_pagealloc() required and CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y should also work correctly.

In this function it would not work if the debug_pagealloc param gets
processed later than page_owner, but should be doable in
init_page_owner(), I'll try, thanks.

quoted

+		page_owner_free_stack_disabled = false;
+
 	return 0;
 }
 early_param("page_owner", early_page_owner_param);

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