From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0842E81E17 for ; Fri, 6 Oct 2023 16:39:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232851AbjJFQjl (ORCPT ); Fri, 6 Oct 2023 12:39:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232496AbjJFQjj (ORCPT ); Fri, 6 Oct 2023 12:39:39 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E666AD for ; Fri, 6 Oct 2023 09:39:38 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7730C433C8; Fri, 6 Oct 2023 16:39:36 +0000 (UTC) From: Catalin Marinas To: linux-mm@kvack.org, Andrew Morton Cc: linux-kernel@vger.kernel.org, Mark Rutland , Vlastimil Babka , Peter Collingbourne Subject: [RESEND PATCH] mm: slab: Do not create kmalloc caches smaller than arch_slab_minalign() Date: Fri, 6 Oct 2023 17:39:34 +0100 Message-Id: <20231006163934.3273940-1-catalin.marinas@arm.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible") allows architectures with non-coherent DMA to define a small ARCH_KMALLOC_MINALIGN (e.g. sizeof(unsigned long long)) and this has been enabled on arm64. With KASAN_HW_TAGS enabled, however, ARCH_SLAB_MINALIGN becomes 16 on arm64 (arch_slab_minalign() dynamically selects it since commit d949a8155d13 ("mm: make minimum slab alignment a runtime property")). This can lead to a situation where kmalloc-8 caches are attempted to be created with a kmem_caches.size aligned to 16. When the cache is mergeable, it can lead to kernel warnings like: sysfs: cannot create duplicate filename '/kernel/slab/:d-0000016' CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.0-rc1-00001-gda98843cd306-dirty #5 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: dump_backtrace+0x90/0xe8 show_stack+0x18/0x24 dump_stack_lvl+0x48/0x60 dump_stack+0x18/0x24 sysfs_warn_dup+0x64/0x80 sysfs_create_dir_ns+0xe8/0x108 kobject_add_internal+0x98/0x264 kobject_init_and_add+0x8c/0xd8 sysfs_slab_add+0x12c/0x248 slab_sysfs_init+0x98/0x14c do_one_initcall+0x6c/0x1b0 kernel_init_freeable+0x1c0/0x288 kernel_init+0x24/0x1e0 ret_from_fork+0x10/0x20 kobject: kobject_add_internal failed for :d-0000016 with -EEXIST, don't try to register things with the same name in the same directory. SLUB: Unable to add boot slab dma-kmalloc-8 to sysfs Limit the __kmalloc_minalign() return value (used to create the kmalloc-* caches) to arch_slab_minalign() so that kmalloc-8 caches are skipped when KASAN_HW_TAGS is enabled (both config and runtime). Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible") Signed-off-by: Catalin Marinas Reported-by: Mark Rutland Cc: Andrew Morton Cc: Vlastimil Babka Cc: Peter Collingbourne Cc: # 6.5.x --- The previous post was messed up by my git send-email configuration, so sending it again. Also cc'ing Vlastimil since he reviewed the previous slab changes for ARCH_KMALLOC_MINALIGN. Thanks. mm/slab_common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index cd71f9581e67..8b45922ed295 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -895,10 +895,13 @@ void __init setup_kmalloc_cache_index_table(void) static unsigned int __kmalloc_minalign(void) { + unsigned int minalign = dma_get_cache_alignment(); + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && is_swiotlb_allocated()) - return ARCH_KMALLOC_MINALIGN; - return dma_get_cache_alignment(); + minalign = ARCH_KMALLOC_MINALIGN; + + return ALIGN(minalign, arch_slab_minalign()); } void __init