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 11DE5C001B0 for ; Tue, 15 Aug 2023 19:26:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233852AbjHOTZ6 (ORCPT ); Tue, 15 Aug 2023 15:25:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239926AbjHOTZo (ORCPT ); Tue, 15 Aug 2023 15:25:44 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF9FB1FF1 for ; Tue, 15 Aug 2023 12:24:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692127461; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5iwNtXyVC59To71ph/ZKdTniHJJAlun4JMzYFhELgT0=; b=U3bJZhCfZt9BXQkaED6xb/uQTYN//XkIY+1DWV0m64VOu99MyYQCUUcAsqyW0R78tIvSFQ Z/1GabmfCJAQju5OtDoSdrVvLx/T3LSMeNlx2Gz4tSSe2DG1C/jiPi8QMkqprMpKgpWjjG untahbQhDyPO2MFQvITNe42hQo3tG4U= Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-132-bvII6brRMXyjddBjOOyuuw-1; Tue, 15 Aug 2023 15:24:19 -0400 X-MC-Unique: bvII6brRMXyjddBjOOyuuw-1 Received: by mail-oi1-f199.google.com with SMTP id 5614622812f47-3a716f3b5b9so2111455b6e.1 for ; Tue, 15 Aug 2023 12:24:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692127459; x=1692732259; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=5iwNtXyVC59To71ph/ZKdTniHJJAlun4JMzYFhELgT0=; b=A3sqn2/hmARvj6b/QEltdnvCA5TeZalx0SlyMhNUHNej2xP/8KbKhCszEKIx5IX/WE x59KfqY9B3U2fDjLYKm5oAVDzNQ/Pua2DY99rawlK5oU280tRfYju4Cpuw+YyMpSF/nM J3tHC0I8nctGO6qgRf/YaqgLSvdckjzKDDz1N9Cuh/l+wXXSKqytXg+xxfWWBOdtmzxM Xrsqh5hn0KfIDHnBxzSi/Z+o7piGEAQi4+0mT6ygn0VpDftBDJqBOt/Y6CjLil9DuTZc fdyPCOY/e3j66YjbVUQCrf3GRdzhpzS3I54C85YLQbNvpCH/9SNpBnFrMN0U98Lz4h0f tyYw== X-Gm-Message-State: AOJu0YyuRyLljdLLFMACbNzcpf+S/A0wIt3WoHLTwIYUBjHqpFCmxZTr XhWk3EIkPce4Bwcm8cX3H91ntU0AhJ2ypXtCxSxPB8N6RGXwPCSl/CylSvO7jOuaUjHuZ37Y9O8 Mf1bXg7ZC0+spp0BmH+VULQzhcf8= X-Received: by 2002:a05:6808:6509:b0:39e:ab5c:91db with SMTP id fm9-20020a056808650900b0039eab5c91dbmr11345208oib.2.1692127458936; Tue, 15 Aug 2023 12:24:18 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFFjuXoNAblX6khjjlI+bkcGZYW+5MOM2WN4wnXD+J4kH0OodENV23nCGnKZAqUA0vn3/im3g== X-Received: by 2002:a05:6808:6509:b0:39e:ab5c:91db with SMTP id fm9-20020a056808650900b0039eab5c91dbmr11345197oib.2.1692127458625; Tue, 15 Aug 2023 12:24:18 -0700 (PDT) Received: from x1n (cpe5c7695f3aee0-cm5c7695f3aede.cpe.net.cable.rogers.com. [99.254.144.39]) by smtp.gmail.com with ESMTPSA id op29-20020a05620a535d00b0076c84240467sm3941292qkn.52.2023.08.15.12.24.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Aug 2023 12:24:18 -0700 (PDT) Date: Tue, 15 Aug 2023 15:24:16 -0400 From: Peter Xu To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , Jens Axboe , io-uring@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 8/9] mm: Rearrange page flags Message-ID: References: <20230815032645.1393700-1-willy@infradead.org> <20230815032645.1393700-9-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230815032645.1393700-9-willy@infradead.org> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Tue, Aug 15, 2023 at 04:26:44AM +0100, 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. PG_active and PG_workingset move into the second > byte to make room for them. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > include/linux/page-flags.h | 24 +++++++++++------------- > 1 file changed, 11 insertions(+), 13 deletions(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index aabf50dc71a3..6a0dd94b2460 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -99,13 +99,15 @@ > */ > enum pageflags { > PG_locked, /* Page is locked. Don't touch. */ > + PG_writeback, /* Page is under writeback */ > PG_referenced, > PG_uptodate, > PG_dirty, > PG_lru, > + PG_head, /* Must be in bit 6 */ Could there be some explanation on "must be in bit 6" here? Thanks, -- Peter Xu