From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EADA0256D for ; Fri, 9 Jun 2023 12:33:05 +0000 (UTC) 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 46B5B1FDFC; Fri, 9 Jun 2023 12:32:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1686313978; 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=1ZsrEHzsYnyHtsbKLymBWtLxiNzEIMAt6EujZ9H8hQ8=; b=Q3kyfEg8qtDawtF0d9l8bcuIQMXUBls1bY9nnx+FmpdW6CEZBW7leROyAMRuVh7JqWEa03 8o1+LRoCt6PB9j1MtWa4rnl1dnPSXhMsBU2G7choTB/bZuKR4JNjHCHJEq6b9lyS+4Rkyk 8QwY/xh5gDSCLp1bOmjCh6TbBwR2pLE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1686313978; 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=1ZsrEHzsYnyHtsbKLymBWtLxiNzEIMAt6EujZ9H8hQ8=; b=7FncRbw0qFhiQvgGLLF0qQYbko8s1TtF8MAVcJVh/VMUTLs+7VQ20/c5ZDDmuSiTsdry7P 5CkFpj54l/mw5CDg== 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 05BE613A47; Fri, 9 Jun 2023 12:32:58 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id iu1XAPobg2QbQgAAMHmgww (envelope-from ); Fri, 09 Jun 2023 12:32:58 +0000 Message-ID: Date: Fri, 9 Jun 2023 14:32:57 +0200 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH v6 01/17] mm/slab: Decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN Content-Language: en-US To: Catalin Marinas , Linus Torvalds , Christoph Hellwig , Robin Murphy Cc: Arnd Bergmann , Greg Kroah-Hartman , Will Deacon , Marc Zyngier , Andrew Morton , Herbert Xu , Ard Biesheuvel , Isaac Manjarres , Saravana Kannan , Alasdair Kergon , Daniel Vetter , Joerg Roedel , Mark Brown , Mike Snitzer , "Rafael J. Wysocki" , Jonathan Cameron , linux-mm@kvack.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org References: <20230531154836.1366225-1-catalin.marinas@arm.com> <20230531154836.1366225-2-catalin.marinas@arm.com> From: Vlastimil Babka In-Reply-To: <20230531154836.1366225-2-catalin.marinas@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/31/23 17:48, Catalin Marinas wrote: > In preparation for supporting a kmalloc() minimum alignment smaller than > the arch DMA alignment, decouple the two definitions. This requires that > either the kmalloc() caches are aligned to a (run-time) cache-line size > or the DMA API bounces unaligned kmalloc() allocations. Subsequent > patches will implement both options. > > After this patch, ARCH_DMA_MINALIGN is expected to be used in static > alignment annotations and defined by an architecture to be the maximum > alignment for all supported configurations/SoCs in a single Image. > Architectures opting in to a smaller ARCH_KMALLOC_MINALIGN will need to > define its value in the arch headers. > > Since ARCH_DMA_MINALIGN is now always defined, adjust the #ifdef in > dma_get_cache_alignment() so that there is no change for architectures > not requiring a minimum DMA alignment. > > Signed-off-by: Catalin Marinas > Cc: Andrew Morton > Cc: Christoph Hellwig > Cc: Robin Murphy > --- > include/linux/dma-mapping.h | 2 +- > include/linux/slab.h | 14 +++++++++++--- > 2 files changed, 12 insertions(+), 4 deletions(-) > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index 0ee20b764000..3288a1339271 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -545,7 +545,7 @@ static inline int dma_set_min_align_mask(struct device *dev, > > static inline int dma_get_cache_alignment(void) > { > -#ifdef ARCH_DMA_MINALIGN > +#ifdef ARCH_HAS_DMA_MINALIGN > return ARCH_DMA_MINALIGN; > #endif > return 1; > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 6b3e155b70bf..50dcf9cfbf62 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -235,12 +235,20 @@ void kmem_dump_obj(void *object); > * alignment larger than the alignment of a 64-bit integer. > * Setting ARCH_DMA_MINALIGN in arch headers allows that. > */ > -#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8 > +#ifdef ARCH_DMA_MINALIGN > +#define ARCH_HAS_DMA_MINALIGN > +#if ARCH_DMA_MINALIGN > 8 && !defined(ARCH_KMALLOC_MINALIGN) > #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN > -#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN > -#define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN) > +#endif > #else > +#define ARCH_DMA_MINALIGN __alignof__(unsigned long long) > +#endif It seems weird to make slab.h responsible for this part, especially for #define ARCH_HAS_DMA_MINALIGN, which dma-mapping.h consumes. Maybe it would be difficult to do differently due to some dependency hell, but minimally I don't see dma-mapping.h including slab.h so the result is include-order-dependent? Maybe it's included transitively, but then it's fragile and would be better to do explicitly? > + > +#ifndef ARCH_KMALLOC_MINALIGN > #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long) > +#elif ARCH_KMALLOC_MINALIGN > 8 > +#define KMALLOC_MIN_SIZE ARCH_KMALLOC_MINALIGN > +#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE) > #endif > > /* >