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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05130C433B4 for ; Sun, 18 Apr 2021 11:21:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 64DFE61207 for ; Sun, 18 Apr 2021 11:21:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64DFE61207 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 791A96B0036; Sun, 18 Apr 2021 07:21:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 741876B006E; Sun, 18 Apr 2021 07:21:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E2286B0070; Sun, 18 Apr 2021 07:21:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0063.hostedemail.com [216.40.44.63]) by kanga.kvack.org (Postfix) with ESMTP id 42ADF6B0036 for ; Sun, 18 Apr 2021 07:21:27 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id E78795DD7 for ; Sun, 18 Apr 2021 11:21:26 +0000 (UTC) X-FDA: 78045246972.29.5D9DF4F Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) by imf11.hostedemail.com (Postfix) with ESMTP id D12602000242 for ; Sun, 18 Apr 2021 11:21:14 +0000 (UTC) Received: by mail-wr1-f44.google.com with SMTP id a4so31060513wrr.2 for ; Sun, 18 Apr 2021 04:21:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=yHuFjlT5rtKQaeRAFhvfUQECvltMrb+hYlCuEQGxGSA=; b=n705a9a7qdxMFuWE1zX7H+Gwn7R1Ph/HxlJsBZM2OwmgI8on3YCAfTIJ9VILLpPGVN U6Ei9bgVBs4WU0tgRYPLY73PulXN7X8T9DnS/lfiOp0hi2PY7rBteW4MAz4+5uRDWIzC tVQA+Ijyf20lSUQ31OC6X057HKNOPi+pz6Nzkf8RmSCB7uub+bAFeTOPAvt2BEhTUPA9 e95vVEysgGXjcAyKsinTriFeM9DFcYVac9rU5mO+CY2n1SfMhFTrdb724lZinw5eig/R DWL2UVgqLZFgwGhAmloMkMPTn1qsrnfB8ZvGBiW/SI8QnW3O/4TL6LEClDzNGo9C+X4Y G8Ag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=yHuFjlT5rtKQaeRAFhvfUQECvltMrb+hYlCuEQGxGSA=; b=RkEGQ+6bqYDKbNn466/kms0pfHhsBQoQrHqD8PAFLdYibOMs/u0EAoUs2tWRwoQFet hRb7LlmoAw3qBHMIcJTmDvDZF59m/9Z9Vg5c8YhywY7ZHT2G5ggb3Kh7PEgTa1XJ7kSh hDV3h55Cmz94WSF0SjFSBZbFj4GtT99Jc3DsSFp8fFhsWwLzj7GQu7+DrO3ot3c6/7gu f//92yFJ05qTXcWo2gIa4WEGHMgaqNsmLvPi40SIA9/r2a7JSwYmOXHXbwx4WHd+DHgE eQpof5tzFpSAe4fK9SPQ8JEkb5e82g45uG9B+Xqx7rEp0WEc6JKlLzPBN2CE3yW/hTTs tAmw== X-Gm-Message-State: AOAM533frTnVWDMXNo2p4+py/RNB7eb+KroLMyDE1tbXgq4aouwzaP46 +AFNOBSE4h3Cf83vPfoLti+2Xw== X-Google-Smtp-Source: ABdhPJy/WC+K/XtmqLOKo5IrEBVbL+R26kxzPf1pRpKWFGvT15zr5cY0imTHGxHtMkaaPLJEz/z5Qw== X-Received: by 2002:a5d:5146:: with SMTP id u6mr8768015wrt.408.1618744885216; Sun, 18 Apr 2021 04:21:25 -0700 (PDT) Received: from apalos.home (ppp-94-65-92-88.home.otenet.gr. [94.65.92.88]) by smtp.gmail.com with ESMTPSA id i12sm17113748wrm.77.2021.04.18.04.21.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 18 Apr 2021 04:21:24 -0700 (PDT) Date: Sun, 18 Apr 2021 14:21:21 +0300 From: Ilias Apalodimas To: Matthew Wilcox Cc: brouer@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, mcroce@linux.microsoft.com, grygorii.strashko@ti.com, arnd@kernel.org, hch@lst.de, linux-snps-arc@lists.infradead.org, mhocko@kernel.org, mgorman@suse.de Subject: Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems Message-ID: References: <20210416230724.2519198-1-willy@infradead.org> <20210416230724.2519198-2-willy@infradead.org> <20210417024522.GP2531743@casper.infradead.org> <20210417202240.GS2531743@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210417202240.GS2531743@casper.infradead.org> X-Stat-Signature: 9rkgxa6i3ryazbqsws3ub8c8kza68kwm X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D12602000242 Received-SPF: none (linaro.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-wr1-f44.google.com; client-ip=209.85.221.44 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618744874-598996 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 Sat, Apr 17, 2021 at 09:22:40PM +0100, Matthew Wilcox wrote: > On Sat, Apr 17, 2021 at 09:32:06PM +0300, Ilias Apalodimas wrote: > > > +static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr) > > > +{ > > > + page->dma_addr[0] = addr; > > > + if (sizeof(dma_addr_t) > sizeof(unsigned long)) > > > + page->dma_addr[1] = addr >> 16 >> 16; > > > > The 'error' that was reported will never trigger right? > > I assume this was compiled with dma_addr_t as 32bits (so it triggered the > > compilation error), but the if check will never allow this codepath to run. > > If so can we add a comment explaining this, since none of us will remember why > > in 6 months from now? > > That's right. I compiled it all three ways -- 32-bit, 64-bit dma, 32-bit long > and 64-bit. The 32/64 bit case turn into: > > if (0) > page->dma_addr[1] = addr >> 16 >> 16; > > which gets elided. So the only case that has to work is 64-bit dma and > 32-bit long. > > I can replace this with upper_32_bits(). > Ok up to you, I don't mind either way and thanks for solving this! Acked-by: Ilias Apalodimas