On Wed, Nov 04, 2015 at 09:28:34AM -0600, Christoph Lameter wrote: > On Wed, 4 Nov 2015, Catalin Marinas wrote: > > > BTW, assuming L1_CACHE_BYTES is 512 (I don't ever see this happening but > > just in theory), we potentially have the same issue. What would save us > > is that INDEX_NODE would match the first "kmalloc-512" cache, so we have > > it pre-populated. > > Ok maybe add some BUILD_BUG_ONs to ensure that builds fail until we have > addressed that. A BUILD_BUG_ON should be fine. Thinking some more, I think if KMALLOC_MIN_SIZE is 128, there is no gain with off-slab management since the freelist allocation would still be 128 bytes. An alternative to reverting while still having a little benefit of off-slab for 256 bytes objects (rather than 512 as we would get with the revert): diff --git a/mm/slab.c b/mm/slab.c index 4fcc5dd8d5a6..ac32b4a0f2ec 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2212,8 +2212,8 @@ __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 && - !(flags & SLAB_NOLEAKTRACE)) + if ((size >= (PAGE_SIZE >> 5)) && (size > KMALLOC_MIN_SIZE) && + !slab_early_init && !(flags & SLAB_NOLEAKTRACE)) /* * Size is large, assume best to place the slab management obj * off-slab (should allow better packing of objs). Whichever you prefer. -- Catalin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>