@@ -282,6 +282,7 @@ static void kmem_cache_node_init(struct kmem_cache_node *parent)
#define CFLGS_OFF_SLAB (0x80000000UL)
#define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB)
+#define OFF_SLAB_MIN_SIZE (max_t(size_t, PAGE_SIZE >> 5, KMALLOC_MIN_SIZE + 1))
#define BATCHREFILL_LIMIT 16
/*
@@ -2212,7 +2213,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
* it too early on. Always use on-slab management when
* SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
*/
- if ((size >= (PAGE_SIZE >> 5)) && !slab_early_init &&
+ if (size >= OFF_SLAB_MIN_SIZE && !slab_early_init &&
!(flags & SLAB_NOLEAKTRACE))
/*
* Size is large, assume best to place the slab management obj
@@ -2276,7 +2277,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
/*
* This is a possibility for one of the kmalloc_{dma,}_caches.
* But since we go off slab only for object size greater than
- * PAGE_SIZE/8, and kmalloc_{dma,}_caches get created
+ * OFF_SLAB_MIN_SIZE, and kmalloc_{dma,}_caches get created
* in ascending order,this should not happen at all.
* But leave a BUG_ON for some lucky dude.
*/
Commit 8fc9cf420b36 ("slab: make more slab management structure off the slab") enables off-slab management objects for sizes starting with PAGE_SIZE >> 5. This means 128 bytes for a 4KB page configuration. However, on systems with a KMALLOC_MIN_SIZE of 128 (arm64 in 4.4), such optimisation does not make sense since the slab management allocation would take 128 bytes anyway (even though freelist_size is 32) with the additional overhead of another allocation. This patch introduces an OFF_SLAB_MIN_SIZE macro which takes KMALLOC_MIN_SIZE into account. It also solves a slab bug on arm64 where the first kmalloc_cache to be initialised after slab_early_init = 0, "kmalloc-128", fails to allocate off-slab management objects from the same "kmalloc-128" cache. Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab") Cc: <stable@vger.kernel.org> # 3.15+ Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> 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> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- mm/slab.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/