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

mm/page_alloc.c

@@ -498,6 +498,7 @@ void prep_compound_page(struct page *page, unsigned int order)
 unsigned int _debug_guardpage_minorder;
 bool _debug_pagealloc_enabled __read_mostly
 			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
+EXPORT_SYMBOL(_debug_pagealloc_enabled);
 bool _debug_guardpage_enabled __read_mostly;
 
 static int __init early_debug_pagealloc(char *buf)

sound/drivers/pcsp/pcsp.c

@@ -14,6 +14,7 @@
 #include <linux/input.h>
 #include <linux/delay.h>
 #include <linux/bitops.h>
+#include <linux/mm.h>
 #include "pcsp_input.h"
 #include "pcsp.h"
 
@@ -148,11 +149,11 @@ static int alsa_card_pcsp_init(struct device *dev)
 		return err;
 	}
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
 	/* Well, CONFIG_DEBUG_PAGEALLOC makes the sound horrible. Lets alert */
-	printk(KERN_WARNING "PCSP: CONFIG_DEBUG_PAGEALLOC is enabled, "
-	       "which may make the sound noisy.\n");
-#endif
+	if (debug_pagealloc_enabled()) {
+		printk(KERN_WARNING "PCSP: CONFIG_DEBUG_PAGEALLOC is enabled, "
+		       "which may make the sound noisy.\n");
+	}
 
 	return 0;
 }