1 files changed, 90 insertions, 33 deletions

diff --git a/mm/page_owner.c b/mm/page_owner.c
index addcbb2ae4e4..dee931184788 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -24,6 +24,9 @@ struct page_owner {
         short last_migrate_reason;
         gfp_t gfp_mask;
         depot_stack_handle_t handle;
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        depot_stack_handle_t free_handle;
+#endif
 };
 
 static bool page_owner_disabled = true;
@@ -102,19 +105,6 @@ static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
         return (void *)page_ext + page_owner_ops.offset;
 }
 
-void __reset_page_owner(struct page *page, unsigned int order)
-{
-        int i;
-        struct page_ext *page_ext;
-
-        for (i = 0; i < (1 << order); i++) {
-                page_ext = lookup_page_ext(page + i);
-                if (unlikely(!page_ext))
-                        continue;
-                __clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
-        }
-}
-
 static inline bool check_recursive_alloc(unsigned long *entries,
                                          unsigned int nr_entries,
                                          unsigned long ip)
@@ -154,18 +144,50 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
         return handle;
 }
 
-static inline void __set_page_owner_handle(struct page_ext *page_ext,
-        depot_stack_handle_t handle, unsigned int order, gfp_t gfp_mask)
+void __reset_page_owner(struct page *page, unsigned int order)
 {
+        int i;
+        struct page_ext *page_ext;
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        depot_stack_handle_t handle = 0;
         struct page_owner *page_owner;
 
-        page_owner = get_page_owner(page_ext);
-        page_owner->handle = handle;
-        page_owner->order = order;
-        page_owner->gfp_mask = gfp_mask;
-        page_owner->last_migrate_reason = -1;
+        if (debug_pagealloc_enabled())
+                handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
+#endif
 
-        __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
+        for (i = 0; i < (1 << order); i++) {
+                page_ext = lookup_page_ext(page + i);
+                if (unlikely(!page_ext))
+                        continue;
+                __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags);
+#ifdef CONFIG_DEBUG_PAGEALLOC
+                if (debug_pagealloc_enabled()) {
+                        page_owner = get_page_owner(page_ext);
+                        page_owner->free_handle = handle;
+                }
+#endif
+        }
+}
+
+static inline void __set_page_owner_handle(struct page *page,
+        struct page_ext *page_ext, depot_stack_handle_t handle,
+        unsigned int order, gfp_t gfp_mask)
+{
+        struct page_owner *page_owner;
+        int i;
+
+        for (i = 0; i < (1 << order); i++) {
+                page_owner = get_page_owner(page_ext);
+                page_owner->handle = handle;
+                page_owner->order = order;
+                page_owner->gfp_mask = gfp_mask;
+                page_owner->last_migrate_reason = -1;
+                __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
+                __set_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags);
+
+                page_ext = lookup_page_ext(page + i);
+        }
 }
 
 noinline void __set_page_owner(struct page *page, unsigned int order,
@@ -178,7 +200,7 @@ noinline void __set_page_owner(struct page *page, unsigned int order,
                 return;
 
         handle = save_stack(gfp_mask);
-        __set_page_owner_handle(page_ext, handle, order, gfp_mask);
+        __set_page_owner_handle(page, page_ext, handle, order, gfp_mask);
 }
 
 void __set_page_owner_migrate_reason(struct page *page, int reason)
@@ -204,8 +226,11 @@ void __split_page_owner(struct page *page, unsigned int order)
 
         page_owner = get_page_owner(page_ext);
         page_owner->order = 0;
-        for (i = 1; i < (1 << order); i++)
-                __copy_page_owner(page, page + i);
+        for (i = 1; i < (1 << order); i++) {
+                page_ext = lookup_page_ext(page + i);
+                page_owner = get_page_owner(page_ext);
+                page_owner->order = 0;
+        }
 }
 
 void __copy_page_owner(struct page *oldpage, struct page *newpage)
@@ -235,6 +260,7 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
          * the new page, which will be freed.
          */
         __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
+        __set_bit(PAGE_EXT_OWNER_ACTIVE, &new_ext->flags);
 }
 
 void pagetypeinfo_showmixedcount_print(struct seq_file *m,
@@ -294,7 +320,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
                         if (unlikely(!page_ext))
                                 continue;
 
-                        if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+                        if (!test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags))
                                 continue;
 
                         page_owner = get_page_owner(page_ext);
@@ -405,20 +431,36 @@ void __dump_page_owner(struct page *page)
         mt = gfpflags_to_migratetype(gfp_mask);
 
         if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
-                pr_alert("page_owner info is not active (free page?)\n");
+                pr_alert("page_owner info is not present (never set?)\n");
                 return;
         }
 
+        if (test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags))
+                pr_alert("page_owner tracks the page as allocated\n");
+        else
+                pr_alert("page_owner tracks the page as freed\n");
+
+        pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
+                 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
+
         handle = READ_ONCE(page_owner->handle);
         if (!handle) {
-                pr_alert("page_owner info is not active (free page?)\n");
-                return;
+                pr_alert("page_owner allocation stack trace missing\n");
+        } else {
+                nr_entries = stack_depot_fetch(handle, &entries);
+                stack_trace_print(entries, nr_entries, 0);
         }
 
-        nr_entries = stack_depot_fetch(handle, &entries);
-        pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
-                 page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
-        stack_trace_print(entries, nr_entries, 0);
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        handle = READ_ONCE(page_owner->free_handle);
+        if (!handle) {
+                pr_alert("page_owner free stack trace missing\n");
+        } else {
+                nr_entries = stack_depot_fetch(handle, &entries);
+                pr_alert("page last free stack trace:\n");
+                stack_trace_print(entries, nr_entries, 0);
+        }
+#endif
 
         if (page_owner->last_migrate_reason != -1)
                 pr_alert("page has been migrated, last migrate reason: %s\n",
@@ -481,9 +523,23 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
                 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
                         continue;
 
+                /*
+                 * Although we do have the info about past allocation of free
+                 * pages, it's not relevant for current memory usage.
+                 */
+                if (!test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags))
+                        continue;
+
                 page_owner = get_page_owner(page_ext);
 
                 /*
+                 * Don't print "tail" pages of high-order allocations as that
+                 * would inflate the stats.
+                 */
+                if (!IS_ALIGNED(pfn, 1 << page_owner->order))
+                        continue;
+
+                /*
                  * Access to page_ext->handle isn't synchronous so we should
                  * be careful to access it.
                  */
@@ -562,7 +618,8 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
                                 continue;
 
                         /* Found early allocated page */
-                        __set_page_owner_handle(page_ext, early_handle, 0, 0);
+                        __set_page_owner_handle(page, page_ext, early_handle,
+                                                0, 0);
                         count++;
                 }
                 cond_resched();