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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B47DFC433EF for ; Thu, 24 Feb 2022 01:37:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229671AbiBXBiD (ORCPT ); Wed, 23 Feb 2022 20:38:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229723AbiBXBhz (ORCPT ); Wed, 23 Feb 2022 20:37:55 -0500 Received: from mail-ed1-x535.google.com (mail-ed1-x535.google.com [IPv6:2a00:1450:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BCBE4506E for ; Wed, 23 Feb 2022 17:37:26 -0800 (PST) Received: by mail-ed1-x535.google.com with SMTP id m3so773437eda.10 for ; Wed, 23 Feb 2022 17:37:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=7rPcGmjhZFqQTd6oy57LGwV/NoXmOrL2/XyqSHiSpT4=; b=FPo99/LglWlYagpTblc5f8caCXuee5xCf55PzVYNgc9j6cWtHyBIxglPXvRcfnlUfF cywQpV10FBgt4cKrkKe0LJ/U3hQXJp1QC/+D50STQzk0+YKVpJURbmhFsWT/+lzTVZQE E6BF+NnkCbYmiGfAQBjZDa0h61YTfQReUC3CubR63oyJluP/1mihSDEvMBNSzPH9iJQf ikH/xinsV5cJeL8NVK32g18s6nnNRNqoXvY1QzMFmxsMjLgslHtoBiTAvdASyKY9JoxR DSEA6OPujdQkZLd75KtuahF641dPHXe9rUDo7acoO9641UUS4jqiapSpN0XlZAOTKeeM wadA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=7rPcGmjhZFqQTd6oy57LGwV/NoXmOrL2/XyqSHiSpT4=; b=I8MfV+iAagRXYRlQT2Srq851ZoGMS2Rjs8JRu2L44sHbXHjSQC08rh43hTlKKhWXPr +cEssZEsEciHf1gjQD93PCp2vT/95zrFpprL/PdMSsMUvtYUqEmIEXg3l9WhI0ScsDZm 5zafZKfnhxSvKshxs6JmPLy3qyA+DImYEIAmVB/rGmM6q+XQlr2u4+taWMdVh1uLZqQ3 UO7TIGtbfoLUuBh0ybusDdXJmSExd0jz79MeWVHtbyqk0oJ13ubH1Y2ctGc28AW96MU5 y8pyjhWfCKmJnM1yc8FI22dfpEPInhs9+jTYZYFn0LUjAYwogc9chUVHE9jxflSiAoga iMrQ== X-Gm-Message-State: AOAM531YJ3lZ84xILLgNWigygCIEicO1cHHBJzrYq4a9DzAGrQV4Uv+e ed0DbcXmQtxNfFppVAdS4VcI9DrliAw= X-Google-Smtp-Source: ABdhPJxqnInks01QQ2dUwRfitRyQdke9fhVXSXZXi2eqzfWyttrlAy/FsDrWU5MrfhqLAvbzzS8VLw== X-Received: by 2002:a17:906:3ac7:b0:6ce:c3a1:3dcf with SMTP id z7-20020a1709063ac700b006cec3a13dcfmr284921ejd.182.1645664639761; Wed, 23 Feb 2022 17:03:59 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id er17sm555582edb.34.2022.02.23.17.03.59 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 23 Feb 2022 17:03:59 -0800 (PST) Date: Thu, 24 Feb 2022 01:03:58 +0000 From: Wei Yang To: Vlastimil Babka Cc: Wei Yang , Matthew Wilcox , Andrew Morton , peterz@infradead.org, will@kernel.org, linyunsheng@huawei.com, aarcange@redhat.com, feng.tang@intel.com, ebiederm@xmission.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: remove offset check on page->compound_head and folio->lru Message-ID: <20220224010358.ttc2mgdevfqddvea@master> Reply-To: Wei Yang References: <20220106235254.19190-1-richard.weiyang@gmail.com> <20220107134059.flxr2hcd6ilb6vt7@master> <20220107160825.13c71fdd871d7d5611d116b9@linux-foundation.org> <20220108081340.3oi2z2rm3cbqozzt@master> <20220123013852.mm7eyn3z26v3hkc2@master> <93c48e68-2266-72ee-0763-65805b94c968@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <93c48e68-2266-72ee-0763-65805b94c968@suse.cz> User-Agent: NeoMutt/20170113 (1.7.2) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 24, 2022 at 11:30:10AM +0100, Vlastimil Babka wrote: [...] >> Hi, Matthew >> >> Are you back from vocation? If you could give more insight on this check, I >> would be appreciated. > >I can offer my insight (which might be of course wrong). Ideally one day >page.lru will be gone and only folio will be used for LRU pages. Then there >won't be a FOLIO_MATCH(lru, lru); and FOLIO_MATCH(compound_head, lru); >won't appear to be redundant anymore. lru is list_head so two pointers and >thus valid pointers are aligned in such a way they can't accidentaly set the >bit 0. > Hmm... I see your change on struct slab. I guess I got your point. Seems we would shrink struct page... -- Wei Yang Help you, Help me