[PATCH] mm, slab/slub: improve error reporting and overhead of cache_from_obj()-fix

[Vlastimil Babka]

The added VM_WARN_ON_ONCE triggers [1] with CONFIG_SLAB, as SLAB_DEBUG_FLAGS
doesn't include SLAB_CONSISTENCY_CHECKS. Move the check under #ifdef
SLUB_DEBUG.

[1] https://lore.kernel.org/r/20200623090213.GW5535@shao2-debian

Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
 mm/slab.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab.h b/mm/slab.h
index 525260217013..e829d9f5e6ef 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -229,8 +229,8 @@ static inline void print_tracking(struct kmem_cache *s, void *object)
  */
 static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t flags)
 {
-	VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS));
 #ifdef CONFIG_SLUB_DEBUG
+	VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS));
 	if (static_branch_unlikely(&slub_debug_enabled))
 		return s->flags & flags;
 #endif
-- 
2.27.0