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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37804C43219 for ; Tue, 1 Nov 2022 17:39:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9FA3C6B0071; Tue, 1 Nov 2022 13:39:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9AA916B0073; Tue, 1 Nov 2022 13:39:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 899D96B0074; Tue, 1 Nov 2022 13:39:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 799C26B0071 for ; Tue, 1 Nov 2022 13:39:46 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3A643AAEB5 for ; Tue, 1 Nov 2022 17:39:46 +0000 (UTC) X-FDA: 80085585972.12.EB9E0EA Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf11.hostedemail.com (Postfix) with ESMTP id 749B140002 for ; Tue, 1 Nov 2022 17:39:45 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 0B7336732D; Tue, 1 Nov 2022 18:39:41 +0100 (CET) Date: Tue, 1 Nov 2022 18:39:40 +0100 From: Christoph Hellwig To: Catalin Marinas Cc: Christoph Hellwig , Greg Kroah-Hartman , Linus Torvalds , Arnd Bergmann , Will Deacon , Marc Zyngier , Andrew Morton , Herbert Xu , Ard Biesheuvel , Isaac Manjarres , Saravana Kannan , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 2/2] treewide: Add the __GFP_PACKED flag to several non-DMA kmalloc() allocations Message-ID: <20221101173940.GA20821@lst.de> References: <20221030084718.GC5278@lst.de> <20221030091349.GA5600@lst.de> <20221101105919.GA13872@lst.de> <20221101172416.GB20381@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667324385; a=rsa-sha256; cv=none; b=lcnPy+FreqKXI793fFEQHawgPgcgKHGlYKLs+Kjm9HKaG9NRnH4sLhuTWeXvKYHCKblkLJ zdPu4+kCmrXFdhAog7qqwgvIqGWRod427DFj78umkjP+XVawD6ZhOp5+xBPme1LgeJPkYV OgIOMKKkvG8kRdCuzzXVCz4dCoZBTSc= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none; dmarc=none; spf=none (imf11.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667324385; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5xxElhvOVhxZJKduOS2Sd+Yccc16nvDci9hxObWvjP4=; b=3mvh6Pnv7w7x7sC2D29tw9wP9kv47S838Ad8hVNWEsBD4doF0gAsB5WER961E0YR6eO7Nx tVbV8JzaAn1Ygu1Gno/40CM1/In85csheRk6yjke2SZUvNaxUaKq3nBqu17DkfJ9/NM9B3 ZAtqkuz7IkxT9Nna8l7UaLiqCMufKjI= X-Stat-Signature: qtn6knpn6spxfr9f4661xtx5tgz4rfqn X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 749B140002 X-Rspam-User: Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=none; spf=none (imf11.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de X-HE-Tag: 1667324385-8643 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 01, 2022 at 05:32:14PM +0000, Catalin Marinas wrote: > There's also the case of low-end phones with all RAM below 4GB and arm64 > doesn't allocate the swiotlb. Not sure those vendors would go with a > recent kernel anyway. > > So the need for swiotlb now changes from 32-bit DMA to any DMA > (non-coherent but we can't tell upfront when booting, devices may be > initialised pretty late). Yes. The other option would be to use the dma coherent pool for the bouncing, which must be present on non-coherent systems anyway. But it would require us to write a new set of bounce buffering routines.