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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,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 DF514C433ED for ; Wed, 12 May 2021 16:47:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 471206101B for ; Wed, 12 May 2021 16:47:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 471206101B 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 ACCAD6B0070; Wed, 12 May 2021 12:47:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AA3D96B0071; Wed, 12 May 2021 12:47:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8CF236B0072; Wed, 12 May 2021 12:47:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0207.hostedemail.com [216.40.44.207]) by kanga.kvack.org (Postfix) with ESMTP id 575FF6B0070 for ; Wed, 12 May 2021 12:47:52 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id F0527181AEF3E for ; Wed, 12 May 2021 16:47:51 +0000 (UTC) X-FDA: 78133160742.32.C1CE3C6 Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) by imf20.hostedemail.com (Postfix) with ESMTP id 7C7D23F7 for ; Wed, 12 May 2021 16:47:51 +0000 (UTC) Received: by mail-wm1-f42.google.com with SMTP id b11-20020a7bc24b0000b0290148da0694ffso77819wmj.2 for ; Wed, 12 May 2021 09:47:51 -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=bDKYc6juyaymxPVjFoz4H55W1iGwXmuC+dG6aoLf7OA=; b=oYirGOrNIcNwMpkAHzcPYl0Qh5mhW1k7/1qO+qzT05aC765M6Vsg9BuZtavalWCBO4 o0QFswgOc95tPHp89yndOoxlZuw/0PdSI92mJB+WH7RbEltI1ssXo8LnPWsjipjaUxDk zU7GzUCqM+wMOsQSQfe0hfqEA6EwcKRXkr5EipMQ3f2eGD+NfX7ZFw3a50AXswFhUYWK yhuezdiXWJFTiSqM7Rq1vNWZ3erRdlRa6DfSFrGgIEAGl6M4KcuKaH7Yr9vq6BjeuAxR yi8+3GK4WThFGnMUvhKKqAgImphjXzMWiWeHz9bUnHWmnabS4XKRe88d/uG97oFfql2n lr3w== 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=bDKYc6juyaymxPVjFoz4H55W1iGwXmuC+dG6aoLf7OA=; b=gQfQYxgxT0sI535Sp/xqxCr0ocCB7k7lL2tnAgltP1Ygp65RyF9hnBMo3XLowB4w6g apJCeUZ7rEzLwfi1+QBfNc9G1oRpVzW5RB1C5viNLFgz4gon3c9goJjqoIZWxFCc6ACM +MosJfmEX/ZiXk3mJIAO7pOO0eSTSLnc+1tGGTbc4wf1yGd/Viqi6pHs65ABZ1omG5JA bfafPILZ+pWKLazPux9fvcOOi7RjwmwLtndHULSCutU5a8+059CjcPOZlLffrtMfWyjB KnYTjBc5U/5HuGcRBXe2sbEOx9c8fvcCsPHhy5gqbJmkx5/eIM0Iz+rsP6jfptT2YjV9 Tyag== X-Gm-Message-State: AOAM533yjzJ5vRybips9qcpClJmFV8Nc67ouNfGBn0eZqSLiF69q96Yq pHI0rPa8I3zfy+MijYJOtsTBhA== X-Google-Smtp-Source: ABdhPJzDMlMeT7C3maJdPrl7Y+VmQFC0wDQfotNCrVBtjxuloaDP335rfrwZkK1gstgOHCj/mFuZ5w== X-Received: by 2002:a7b:c841:: with SMTP id c1mr39895803wml.123.1620838070248; Wed, 12 May 2021 09:47:50 -0700 (PDT) Received: from apalos.home ([94.69.77.156]) by smtp.gmail.com with ESMTPSA id d9sm210203wrp.47.2021.05.12.09.47.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 May 2021 09:47:49 -0700 (PDT) Date: Wed, 12 May 2021 19:47:44 +0300 From: Ilias Apalodimas To: Matthew Wilcox Cc: Matteo Croce , Networking , Linux-MM , Ayush Sawal , Vinay Kumar Yadav , Rohit Maheshwari , "David S. Miller" , Jakub Kicinski , Thomas Petazzoni , Marcin Wojtas , Russell King , Mirko Lindner , Stephen Hemminger , Tariq Toukan , Jesper Dangaard Brouer , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Boris Pismenny , Arnd Bergmann , Andrew Morton , "Peter Zijlstra (Intel)" , Vlastimil Babka , Yu Zhao , Will Deacon , Michel Lespinasse , Fenghua Yu , Roman Gushchin , Hugh Dickins , Peter Xu , Jason Gunthorpe , Jonathan Lemon , Alexander Lobakin , Cong Wang , wenxu , Kevin Hao , Jakub Sitnicki , Marco Elver , Willem de Bruijn , Miaohe Lin , Yunsheng Lin , Guillaume Nault , open list , linux-rdma@vger.kernel.org, bpf , Eric Dumazet , David Ahern , Lorenzo Bianconi , Saeed Mahameed , Andrew Lunn , Paolo Abeni , Sven Auhagen Subject: Re: [PATCH net-next v4 1/4] mm: add a signature in struct page Message-ID: References: <20210511133118.15012-1-mcroce@linux.microsoft.com> <20210511133118.15012-2-mcroce@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linaro.org header.s=google header.b=oYirGOrN; dmarc=pass (policy=none) header.from=linaro.org; spf=pass (imf20.hostedemail.com: domain of ilias.apalodimas@linaro.org designates 209.85.128.42 as permitted sender) smtp.mailfrom=ilias.apalodimas@linaro.org X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7C7D23F7 X-Stat-Signature: 671gb7iojadptd3jooaqxeswxnnd7b1x Received-SPF: none (linaro.org>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-wm1-f42.google.com; client-ip=209.85.128.42 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620838071-899790 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 Wed, May 12, 2021 at 04:57:25PM +0100, Matthew Wilcox wrote: > On Tue, May 11, 2021 at 05:25:36PM +0300, Ilias Apalodimas wrote: > > Nope not at all, either would work. we'll switch to that > > You'll need something like this because of the current use of > page->index to mean "pfmemalloc". > Yes, I was somehow under the impression that was already merged. We'll include it in the series, with your Co-developed-by tag. Thanks /Ilias > From ecd6d912056a21bbe55d997c01f96b0b8b9fbc31 Mon Sep 17 00:00:00 2001 > From: "Matthew Wilcox (Oracle)" > Date: Fri, 16 Apr 2021 18:12:33 -0400 > Subject: [PATCH] mm: Indicate pfmemalloc pages in compound_head > > The net page_pool wants to use a magic value to identify page pool pages. > The best place to put it is in the first word where it can be clearly a > non-pointer value. That means shifting dma_addr up to alias with ->index, > which means we need to find another way to indicate page_is_pfmemalloc(). > Since page_pool doesn't want to set its magic value on pages which are > pfmemalloc, we can use bit 1 of compound_head to indicate that the page > came from the memory reserves. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > include/linux/mm.h | 12 +++++++----- > include/linux/mm_types.h | 7 +++---- > 2 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index bd21864449bf..4f9b2007efad 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1670,10 +1670,12 @@ struct address_space *page_mapping(struct page *page); > static inline bool page_is_pfmemalloc(const struct page *page) > { > /* > - * Page index cannot be this large so this must be > - * a pfmemalloc page. > + * This is not a tail page; compound_head of a head page is unused > + * at return from the page allocator, and will be overwritten > + * by callers who do not care whether the page came from the > + * reserves. > */ > - return page->index == -1UL; > + return page->compound_head & 2; > } > > /* > @@ -1682,12 +1684,12 @@ static inline bool page_is_pfmemalloc(const struct page *page) > */ > static inline void set_page_pfmemalloc(struct page *page) > { > - page->index = -1UL; > + page->compound_head = 2; > } > > static inline void clear_page_pfmemalloc(struct page *page) > { > - page->index = 0; > + page->compound_head = 0; > } > > /* > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 5aacc1c10a45..1352e278939b 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -96,10 +96,9 @@ struct page { > unsigned long private; > }; > struct { /* page_pool used by netstack */ > - /** > - * @dma_addr: might require a 64-bit value on > - * 32-bit architectures. > - */ > + unsigned long pp_magic; > + struct page_pool *pp; > + unsigned long _pp_mapping_pad; > unsigned long dma_addr[2]; > }; > struct { /* slab, slob and slub */ > -- > 2.30.2 >