[PATCH v3 2/2] mm: Check kmem_create_cache flags are commons

[Thomas Garnier <thgarnie@google.com>]

Verify that kmem_create_cache flags are not allocator specific. It is
done before removing flags that are not available with the current
configuration.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
Based on next-20161027
---
 mm/slab.h        | 15 +++++++++++++++
 mm/slab_common.c |  6 ++++++
 2 files changed, 21 insertions(+)

diff --git a/mm/slab.h b/mm/slab.h
index 9653f2e..3b11896 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -142,8 +142,23 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 #define SLAB_CACHE_FLAGS (0)
 #endif
 
+/* Common flags available with current configuration */
 #define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
 
+/* Common flags permitted for kmem_cache_create */
+#define SLAB_FLAGS_PERMITTED (SLAB_CORE_FLAGS | \
+			      SLAB_RED_ZONE | \
+			      SLAB_POISON | \
+			      SLAB_STORE_USER | \
+			      SLAB_TRACE | \
+			      SLAB_CONSISTENCY_CHECKS | \
+			      SLAB_MEM_SPREAD | \
+			      SLAB_NOLEAKTRACE | \
+			      SLAB_RECLAIM_ACCOUNT | \
+			      SLAB_TEMPORARY | \
+			      SLAB_NOTRACK | \
+			      SLAB_ACCOUNT)
+
 int __kmem_cache_shutdown(struct kmem_cache *);
 void __kmem_cache_release(struct kmem_cache *);
 int __kmem_cache_shrink(struct kmem_cache *, bool);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 329b038..5e01994 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -404,6 +404,12 @@ kmem_cache_create(const char *name, size_t size, size_t align,
 		goto out_unlock;
 	}
 
+	/* Refuse requests with allocator specific flags */
+	if (flags & ~SLAB_FLAGS_PERMITTED) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
 	/*
 	 * Some allocators will constraint the set of valid flags to a subset
 	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
-- 
2.8.0.rc3.226.g39d4020

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