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 C3D75E95A91 for ; Mon, 9 Oct 2023 08:23:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234394AbjJIIXA (ORCPT ); Mon, 9 Oct 2023 04:23:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234375AbjJIIW5 (ORCPT ); Mon, 9 Oct 2023 04:22:57 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E745A6 for ; Mon, 9 Oct 2023 01:22:54 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id D66BF1F381; Mon, 9 Oct 2023 08:22:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1696839772; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ltim8RkRSSqPgm0ql2XAEhJ6hUxAtgiV2v1yn1uhPQM=; b=Dnp9qdIkDf2OXVviSN1s+N/4/lXQO89UbuJsLcH0zIqIDaWyQPlRxUDnV/mjeQhyf6qFYC 0ELbIZJNi5Tqvg9BY8+Y4+f4BihLv1RyKBeOPP/V3vk8o21eRzK583DhmEGexY2D3GgDjL y33/+gBBASG4oaEF8quNzihBeNZtrQ8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1696839772; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ltim8RkRSSqPgm0ql2XAEhJ6hUxAtgiV2v1yn1uhPQM=; b=Jf2niAiYSKt+zb609/CfRb5OzE2JbOUud7bw+DR6dAyIF359So3j+SgdFtIO/Wg65uDdNg W+cv6vXq63XUlYDA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id B1E4B13586; Mon, 9 Oct 2023 08:22:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id JjK5Kly4I2WkPwAAMHmgww (envelope-from ); Mon, 09 Oct 2023 08:22:52 +0000 Message-ID: Date: Mon, 9 Oct 2023 10:22:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [RESEND PATCH] mm: slab: Do not create kmalloc caches smaller than arch_slab_minalign() Content-Language: en-US To: Catalin Marinas , linux-mm@kvack.org, Andrew Morton Cc: linux-kernel@vger.kernel.org, Mark Rutland , Peter Collingbourne , Petr Tesarik References: <20231006163934.3273940-1-catalin.marinas@arm.com> From: Vlastimil Babka In-Reply-To: <20231006163934.3273940-1-catalin.marinas@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/6/23 18:39, Catalin Marinas wrote: > 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. It also touches only slab files so I can take it via slab tree. > 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()); Could it be max() instead of ALIGN()? It would be more obvious, at least to me :) > } > > void __init