vmscan: print shrink_slab symbol name on negative shrinker objects

When a shrinker has a negative number of objects to delete, the symbol
name of the shrinker should be printed, not shrink_slab.  This also makes
the error message slightly more informative.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmscan.c

@@ -214,8 +214,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
 		do_div(delta, lru_pages + 1);
 		shrinker->nr += delta;
 		if (shrinker->nr < 0) {
-			printk(KERN_ERR "%s: nr=%ld\n",
-					__func__, shrinker->nr);
+			printk(KERN_ERR "shrink_slab: %pF negative objects to "
+			       "delete nr=%ld\n",
+			       shrinker->shrink, shrinker->nr);
 			shrinker->nr = max_pass;
 		}