Commit f3a3c320 authored Mar 15, 2016 by Joonsoo Kim Committed by Linus Torvalds Mar 15, 2016

mm/slab: do not change cache size if debug pagealloc isn't possible



We can fail to setup off slab in some conditions.  Even in this case,
debug pagealloc increases cache size to PAGE_SIZE in advance and it is
waste because debug pagealloc cannot work for it when it isn't the off
slab.  To improve this situation, this patch checks first that this
cache with increased size is suitable for off slab.  It actually
increases cache size when it is suitable for off-slab, so possible waste
is removed.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
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: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 158e319b

mm/slab.c

+11 −4

Original line number	Diff line number	Diff line
		@@ -2206,10 +2206,17 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
		*/
		if (debug_pagealloc_enabled() && (flags & SLAB_POISON) &&
		!slab_early_init && size >= kmalloc_size(INDEX_NODE) &&
		size >= 256 && cachep->object_size > cache_line_size() &&
		size < PAGE_SIZE) {
		cachep->obj_offset += PAGE_SIZE - size;
		size = PAGE_SIZE;
		size >= 256 && cachep->object_size > cache_line_size()) {
		if (size < PAGE_SIZE \|\| size % PAGE_SIZE == 0) {
		size_t tmp_size = ALIGN(size, PAGE_SIZE);

		if (set_off_slab_cache(cachep, tmp_size, flags)) {
		flags \|= CFLGS_OFF_SLAB;
		cachep->obj_offset += tmp_size - size;
		size = tmp_size;
		goto done;
		}
		}
		}
		#endif

Admin message