kmemcheck: add hooks for the page allocator

This adds support for tracking the initializedness of memory that
was allocated with the page allocator. Highmem requests are not
tracked.

Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

[build fix for !CONFIG_KMEMCHECK]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 17d5f539a9aa..0727896a88ac 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -23,6 +23,7 @@
 #include <linux/bootmem.h>
 #include <linux/compiler.h>
 #include <linux/kernel.h>
+#include <linux/kmemcheck.h>
 #include <linux/module.h>
 #include <linux/suspend.h>
 #include <linux/pagevec.h>
@@ -546,6 +547,8 @@ static void __free_pages_ok(struct page *page, unsigned int order)
         int i;
         int bad = 0;
 
+        kmemcheck_free_shadow(page, order);
+
         for (i = 0 ; i < (1 << order) ; ++i)
                 bad += free_pages_check(page + i);
         if (bad)
@@ -994,6 +997,8 @@ static void free_hot_cold_page(struct page *page, int cold)
         struct per_cpu_pages *pcp;
         unsigned long flags;
 
+        kmemcheck_free_shadow(page, 0);
+
         if (PageAnon(page))
                 page->mapping = NULL;
         if (free_pages_check(page))
@@ -1047,6 +1052,16 @@ void split_page(struct page *page, unsigned int order)
 
         VM_BUG_ON(PageCompound(page));
         VM_BUG_ON(!page_count(page));
+
+#ifdef CONFIG_KMEMCHECK
+        /*
+         * Split shadow pages too, because free(page[0]) would
+         * otherwise free the whole shadow.
+         */
+        if (kmemcheck_page_is_tracked(page))
+                split_page(virt_to_page(page[0].shadow), order);
+#endif
+
         for (i = 1; i < (1 << order); i++)
                 set_page_refcounted(page + i);
 }
@@ -1667,7 +1682,10 @@ nopage:
                 dump_stack();
                 show_mem();
         }
+        return page;
 got_pg:
+        if (kmemcheck_enabled)
+                kmemcheck_pagealloc_alloc(page, order, gfp_mask);
         return page;
 }
 EXPORT_SYMBOL(__alloc_pages_internal);