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 26C85C0015E for ; Tue, 15 Aug 2023 04:32:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233883AbjHOEcE (ORCPT ); Tue, 15 Aug 2023 00:32:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231424AbjHOEbg (ORCPT ); Tue, 15 Aug 2023 00:31:36 -0400 Received: from mail-lj1-x22a.google.com (mail-lj1-x22a.google.com [IPv6:2a00:1450:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2045DEE for ; Mon, 14 Aug 2023 21:31:33 -0700 (PDT) Received: by mail-lj1-x22a.google.com with SMTP id 38308e7fff4ca-2b9dc1bff38so74163761fa.1 for ; Mon, 14 Aug 2023 21:31:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1692073891; x=1692678691; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=DBlFKKqfybtx8tz9xk8muyf7F4xpNnCFr4X/1vnivn8=; b=VRJDrmJ3m+x1zee6kxS971ngY43vMD+leBkxiSjfk+LOCfKaeTHJ2RLRsHEzKK4yLX qGhEcQEBqN6yli5SdXLnrAR6jvak/EJGWLE/jtawFBlR3lLmcZS8hRoFo1uTuTRAJ2tm R/P4aOKHUlBADAXaYtANS+vpjorqNJnaGadXKr+ZrzNcLxtp4Cce7Hqpl+jCS9qt5CQ3 oeXGsTKMW7AlAR6n+j4iS2VIrKckqGlVRHknu3bYHqjMHwvz1viNCB7KbpR3REZZ4qHI 988PcgPM8MwkT6ppuQHCaW8AK1WtrDZokr3ZxtiMYsqPPP7ql6DzjsCqOlzedrcfofCy 6/iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692073891; x=1692678691; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=DBlFKKqfybtx8tz9xk8muyf7F4xpNnCFr4X/1vnivn8=; b=DlE8miDE82XLSjIgaXTkWwD/bWOPWUz0LQXDUbxaP19JvKqSplM6vGM8S0hTZXYHnU CllYZNtgypBG2XpYYcIbGNGSLHCYBcRfM4Z2qpVYFVxETBdQbeeK1KExQz97dqE01Z3Z trmSeJn/X49qv+rb5p1OnIL+qyP/KKgpXz1r2n+wdZx3CTkYSIpqDJgy04oobsMoKbLk aMSXe1sPSAPZkr2au+ASxMDULQrQDu3xTpoaqQWyeX74PqASkCKSaykro3BvahH+PFvI x/50EIS9BMem5+7eb93qNkGEhVnd2rYQRXFraPRWNax+VAgV6HOq36PMgtrfaUJ1jGoN 8A1w== X-Gm-Message-State: AOJu0YyqtSxZsKH5C5c4u3It3tQ3CS2j9fo7HSrSIdXYZ8Qbo59/x8VT KzjbQaeCOG7Ec2mBWQUaL1WB6rx33xNhYqaKgBfiFg== X-Google-Smtp-Source: AGHT+IEMFtSNin2OGXKyImz6ibXziYrcLSULtnM6cKYCRJUZ/wsdK2qyyN/WaHJv0VMDynk0WlFBYzLHXnGnAWX74tE= X-Received: by 2002:a2e:96d9:0:b0:2bb:8cd9:ea29 with SMTP id d25-20020a2e96d9000000b002bb8cd9ea29mr338543ljj.39.1692073891005; Mon, 14 Aug 2023 21:31:31 -0700 (PDT) MIME-Version: 1.0 References: <20230815032645.1393700-1-willy@infradead.org> <20230815032645.1393700-9-willy@infradead.org> In-Reply-To: <20230815032645.1393700-9-willy@infradead.org> From: Yosry Ahmed Date: Mon, 14 Aug 2023 21:30:54 -0700 Message-ID: Subject: Re: [PATCH 8/9] mm: Rearrange page flags To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , Jens Axboe , io-uring@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Mon, Aug 14, 2023 at 8:27=E2=80=AFPM Matthew Wilcox (Oracle) wrote: > > Move PG_writeback into bottom byte so that it can use PG_waiters in a > later patch. Move PG_head into bottom byte as well to match with where > 'order' is moving next. Sorry if that's obvious, but why do we want to move PG_head to where 'order' is moving? I thought we would want to avoid an overlap to avoid mistaking the first tail page of a high-order compound page as a head page?