Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032755AbbKEN2V (ORCPT ); Thu, 5 Nov 2015 08:28:21 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60973 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031373AbbKEN2U (ORCPT ); Thu, 5 Nov 2015 08:28:20 -0500 Date: Thu, 5 Nov 2015 05:31:39 -0800 From: Andrew Morton To: Catalin Marinas Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Geert Uytterhoeven , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim Subject: Re: [PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE Message-Id: <20151105053139.e38214a9.akpm@linux-foundation.org> In-Reply-To: <1446724235-31400-1-git-send-email-catalin.marinas@arm.com> References: <20151105043155.GA20374@js1304-P5Q-DELUXE> <1446724235-31400-1-git-send-email-catalin.marinas@arm.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 31 On Thu, 5 Nov 2015 11:50:35 +0000 Catalin Marinas wrote: > 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. That all seems to be quite minor stuff. > Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab") > Cc: # 3.15+ Yet you believe the fix should be backported. So, the usual refrain: when fixing a bug, please describe the end-user visible effects of that bug. -- 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/