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.

[[email protected]: clean up code, per Christian]
Signed-off-by: Joonsoo Kim <[email protected]>
Reviewed-by: Christian Borntraeger <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Takashi Iwai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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;
 }