Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754587AbbLIJkj (ORCPT ); Wed, 9 Dec 2015 04:40:39 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45277 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754455AbbLIJk2 (ORCPT ); Wed, 9 Dec 2015 04:40:28 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Catalin Marinas , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linus Torvalds , Luis Henriques Subject: [PATCH 3.16.y-ckt 064/126] mm: slab: only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE Date: Wed, 9 Dec 2015 09:37:14 +0000 Message-Id: <1449653896-5236-65-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> References: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3898 Lines: 92 3.16.7-ckt21 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Catalin Marinas commit d4322d88f5fdf92729dd40f923013414fbb2184d upstream. On systems with a KMALLOC_MIN_SIZE of 128 (arm64, some mips and powerpc configurations defining ARCH_DMA_MINALIGN to 128), the first kmalloc_caches[] entry to be initialised after slab_early_init = 0 is "kmalloc-128" with index 7. Depending on the debug kernel configuration, sizeof(struct kmem_cache) can be larger than 128 resulting in an INDEX_NODE of 8. Commit 8fc9cf420b36 ("slab: make more slab management structure off the slab") enables off-slab management objects for sizes starting with PAGE_SIZE >> 5 (128 bytes for a 4KB page configuration) and the creation of the "kmalloc-128" cache would try to place the management objects off-slab. However, since KMALLOC_MIN_SIZE is already 128 and freelist_size == 32 in __kmem_cache_create(), kmalloc_slab(freelist_size) returns NULL (kmalloc_caches[7] not populated yet). This triggers the following bug on arm64: kernel BUG at /work/Linux/linux-2.6-aarch64/mm/slab.c:2283! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.3.0-rc4+ #540 Hardware name: Juno (DT) PC is at __kmem_cache_create+0x21c/0x280 LR is at __kmem_cache_create+0x210/0x280 [...] Call trace: __kmem_cache_create+0x21c/0x280 create_boot_cache+0x48/0x80 create_kmalloc_cache+0x50/0x88 create_kmalloc_caches+0x4c/0xf4 kmem_cache_init+0x100/0x118 start_kernel+0x214/0x33c This patch introduces an OFF_SLAB_MIN_SIZE definition to avoid off-slab management objects for sizes equal to or smaller than KMALLOC_MIN_SIZE. Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab") Signed-off-by: Catalin Marinas Reported-by: Geert Uytterhoeven Acked-by: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- mm/slab.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 9a8dc5470e5e..084985404fec 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -279,6 +279,7 @@ 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 /* @@ -2328,7 +2329,7 @@ __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 @@ -2392,7 +2393,7 @@ __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. */ -- 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/