Some flags are used internally by the allocators for management
purposes. One example of that is the CFLGS_OFF_SLAB flag that slab uses
to mark that the metadata for that cache is stored outside of the slab.
No cache should ever pass those as a creation flags. We can just ignore
this bit if it happens to be passed (such as when duplicating a cache in
the kmem memcg patches)
Signed-off-by: Glauber Costa <glom...@parallels.com>
CC: Christoph Lameter <c...@linux.com>
CC: Pekka Enberg <penb...@cs.helsinki.fi>
CC: David Rientjes <rient...@google.com>
---
include/linux/slab.h | 4 ++++
mm/slab_common.c | 5 +++++
2 files changed, 9 insertions(+)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0dd2dfa..437c07e 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -79,6 +79,10 @@
/* The following flags affect the page allocator grouping pages by mobility */
#define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are
reclaimable */
#define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are
short-lived */
+
+/* The last flags are reserved for specific internal flags of the allocators */
+#define SLAB_INTERNAL 0xF0000000UL
+
/*
* ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
*
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 9c21725..359ef36 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -107,6 +107,11 @@ struct kmem_cache *kmem_cache_create(const char *name,
size_t size, size_t align
if (!kmem_cache_sanity_check(name, size) == 0)
goto out_locked;
+ /*
+ * Clean any possible internal flags the caller may have passed.
+ * We'll make those decisions ourselves.
+ */
+ flags &= ~SLAB_INTERNAL;
s = __kmem_cache_alias(name, size, align, flags, ctor);
if (s)
--
1.7.11.4
--
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