2 files changed, 25 insertions, 5 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 79e0dff1cdcb..9e06b7f5ecf1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -410,6 +410,13 @@ config DEBUG_KMEMLEAK_TEST
 
           If unsure, say N.
 
+config DEBUG_KMEMLEAK_DEFAULT_OFF
+        bool "Default kmemleak to off"
+        depends on DEBUG_KMEMLEAK
+        help
+          Say Y here to disable kmemleak by default. It can then be enabled
+          on the command line via kmemleak=on.
+
 config DEBUG_PREEMPT
         bool "Debug preemptible kernel"
         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 9afa25b52a83..a5ec42868f99 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -10,6 +10,7 @@
 #include <linux/slab.h>
 #include <linux/scatterlist.h>
 #include <linux/highmem.h>
+#include <linux/kmemleak.h>
 
 /**
  * sg_next - return the next scatterlist entry in a list
@@ -115,17 +116,29 @@ EXPORT_SYMBOL(sg_init_one);
  */
 static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
 {
-        if (nents == SG_MAX_SINGLE_ALLOC)
-                return (struct scatterlist *) __get_free_page(gfp_mask);
-        else
+        if (nents == SG_MAX_SINGLE_ALLOC) {
+                /*
+                 * Kmemleak doesn't track page allocations as they are not
+                 * commonly used (in a raw form) for kernel data structures.
+                 * As we chain together a list of pages and then a normal
+                 * kmalloc (tracked by kmemleak), in order to for that last
+                 * allocation not to become decoupled (and thus a
+                 * false-positive) we need to inform kmemleak of all the
+                 * intermediate allocations.
+                 */
+                void *ptr = (void *) __get_free_page(gfp_mask);
+                kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
+                return ptr;
+        } else
                 return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
 }
 
 static void sg_kfree(struct scatterlist *sg, unsigned int nents)
 {
-        if (nents == SG_MAX_SINGLE_ALLOC)
+        if (nents == SG_MAX_SINGLE_ALLOC) {
+                kmemleak_free(sg);
                 free_page((unsigned long) sg);
-        else
+        } else
                 kfree(sg);
 }