mm/slub: query dynamic DEBUG_PAGEALLOC setting

We can disable debug_pagealloc processing even if the code is compiled
with CONFIG_DEBUG_PAGEALLOC.  This patch changes the code to query
whether it is enabled or not in runtime.

[akpm@linux-foundation.org: clean up code, per Christian]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Takashi Iwai <tiwai@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 712d53474082..2f2f04d39104 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -254,11 +254,10 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
 {
         void *p;
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
+        if (!debug_pagealloc_enabled())
+                return get_freepointer(s, object);
+
         probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p));
-#else
-        p = get_freepointer(s, object);
-#endif
         return p;
 }