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=unavailable 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 CB033C4361B for ; Wed, 12 May 2021 17:02:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D53B613D3 for ; Wed, 12 May 2021 17:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239071AbhELRDw (ORCPT ); Wed, 12 May 2021 13:03:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343571AbhELQxS (ORCPT ); Wed, 12 May 2021 12:53:18 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F3AFC034618 for ; Wed, 12 May 2021 09:47:51 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id o6-20020a05600c4fc6b029015ec06d5269so3397209wmq.0 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=IDJqT2k2Zg9McOYUq/7fhcGSSWBM75Z9davgvuLpqfIfTZTpy/Kx0q6HjTJ43z77L3 XQPNjBnSXFmMxsYrcZ8cQYe3lcBk4gsfdI2Wqh7Ozh5iH4bxXBQOA5nJqDieTye7jmS5 ugcIHqnl49Es03JOb+yMRz8wd/qsQeyzBcP+Q/1U9P02LFDGnrhaS311X7k6XtJ6Qlyt QxzWeANi8o4FkJCRVQq1q6n872wuwGmeyFbwvS57ZgGZw4KRyAdjd9vPcNZy1K0wx6ZP mB0np3DMq1mdl5+TPKvXRV72XBcCzVfLYw/A5ij5y7mTGLO5JtHnLmAjdBDnYXri8lJ7 cnAw== X-Gm-Message-State: AOAM5326ygMeR83LD+rE/rwt23z5lZPQJrZdxIgs+1z+hLbGvGnksbwW Fm1IhVHPU8mnfjKr3UvhfdadFA== 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: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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 >