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/slab.c b/mm/slab.c
index a2152a2573dd..79e15f0a2a6e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2590,7 +2590,10 @@ static int cache_grow(struct kmem_cache *cachep,
          * Be lazy and only check for valid flags here,  keeping it out of the
          * critical path in kmem_cache_alloc().
          */
-        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();
+        }
         local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
         /* Take the node list lock to change the colour_next on this node */