slab: improve checking for invalid gfp_flags

The code goes BUG, but doesn't tell us which bits were unexpectedly set.
Print that out.

Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/mm/slub.c b/mm/slub.c
index cf4f3c4..386bbed 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1377,7 +1377,10 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 	int order;
 	int idx;
 
-	BUG_ON(flags & GFP_SLAB_BUG_MASK);
+	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
+		pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
+		BUG();
+	}
 
 	page = allocate_slab(s,
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);