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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25E59C61DD3 for ; Thu, 3 Sep 2026 06:36:49 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4hb8yS2LKZz2y2X; Thu, 03 Sep 2026 16:36:48 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2001:41d0:1004:224b::57" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1788417408; cv=none; b=h+QEi/MKFmbfJX2ABIYYhUFyfS0jjA00pChKS22j1dz663ftU4WL7MzP2LkNt1Ewwinwj9EJacwZxP1J1s4g1NucfFIh9m6r9TIUXQsd/KsCMBAQoPliIlvT8Tbv09Ybw+w/Bj4DIBPnKMs1U5IHv402R2VRQVdXIhCrTaILEur+fscY14PgBjTN687hJ45ZmwxqjqA851gkiF81ENUAPV0Zqd2FP9SSiM+oJNdZ3OiCcc7hG6jPpgHOA6gUxEg8efFYEcmdQwY45qRPcw3XUJ7w9F+eND3xhimoHmsk3J+p0b3I8hv91r2MjlNk9czYViJh0QU6PztyzP+nED3rSg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1788417408; c=relaxed/relaxed; bh=/AOQl8uMLb7yaSSuMA/y+PSrYIOL2fdOT9lQ+lxwGTs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nnxxmR/u2MPNCfKfoHw859fJdG2MEmJjwVSQ0Bomc/D8ZHMbtzH1DWDg+AzJ/2Di4IKtKX0LQVLprfOy1dz3nSlpKms3OJ1Q86beb+yBhpuAx7QpemkzcCkfLamRC01WD8T+D//pK1Rj7SjosGXP6IXSeeOhi+DorFM9SIxMrXdnihJL4SSjiuXPTIghjUBX/P5OMezsE0iQm5LBBYbfx9goEZfvYmc1u5aZlgBI0b80RtB2XGqDJU50HrmdiGeaXG85GDlno1S04zXJKr1bXHC4nAZ6yWJZrZWt8Fo3N+scr46oKbYoYRXpm7LGEZaZAurCRAValZKgL52oHAi5Zg== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.dev; dkim=pass (1024-bit key; unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=BDPYwWUG; dkim-atps=neutral; spf=pass (client-ip=2001:41d0:1004:224b::57; helo=mta0.migadu.com; envelope-from=qi.zheng@linux.dev; receiver=lists.ozlabs.org) smtp.mailfrom=linux.dev Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=BDPYwWUG; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.dev (client-ip=2001:41d0:1004:224b::57; helo=mta0.migadu.com; envelope-from=qi.zheng@linux.dev; receiver=lists.ozlabs.org) Received: from mta0.migadu.com (out-87.mta0.migadu.com [IPv6:2001:41d0:1004:224b::57]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4hb8yM1wh6z2y2Q for ; Thu, 03 Sep 2026 16:36:35 +1000 (AEST) X-Envelope-To: linuxppc-dev@lists.ozlabs.org DKIM-Signature: a=rsa-sha256; bh=/7zVF87+vSIaxGdnTGi6zl+USr7Ew+xcjHfJdu2PHXQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788417371; v=1; x=1789022171; b=BDPYwWUG2Z6bRep3T0VLBuuKDahOxIhearwYCB9Uw1og7GYuVlylNKYFuk9DYYcpN79wzQxv Jzj5HFC8/TpHPwL4N387Usg237Go+wsjMcy9922gksnD2685r3sFTvRolNcm0p8lyA42w1yhfCR 2I4StrsLfzGRP/Q1GsSuYBDA= X-Envelope-To: linuxppc-dev@lists.ozlabs.org Received: by smtp.migadu.com with ESMTPS id 8473698cd31aeb55; Thu, 03 Sep 2026 06:36:11 +0000 X-Mizu-Trace-ID: 8473698cd31aeb55 X-Migadu-Flow: FLOW_OUT Message-ID: <3775da0f-4068-4fc4-97a7-135eb975ec65@linux.dev> Date: Thu, 3 Sep 2026 14:36:01 +0800 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 04/11] mm/sparse-vmemmap: prepare DAX vmemmap population for section orders To: Muchun Song , Andrew Morton , David Hildenbrand , Oscar Salvador , Madhavan Srinivasan , Michael Ellerman , Jonathan Corbet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, Muchun Song , Lorenzo Stoakes , Mike Rapoport , Nicholas Piggin , Christophe Leroy , Randy Dunlap References: <20260831075342.57563-1-songmuchun@bytedance.com> <20260831075342.57563-5-songmuchun@bytedance.com> From: Qi Zheng In-Reply-To: <20260831075342.57563-5-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/31/26 3:53 PM, Muchun Song wrote: > Device DAX still uses vmemmap_populate_compound_pages() to populate its > compound-page vmemmap mappings. That helper allocates the head and first > tail vmemmap pages explicitly, then reuses the first tail page for the > remaining tail page mappings. > > Device DAX is being moved to the section-based vmemmap optimization > infrastructure, but it cannot switch to the generic section-based > population path yet. Once a later patch records the DAX compound-page > geometry in the section order, DAX head and first-tail PFNs can look > optimizable to the generic helpers as well. > > Add a DAX-specific population flag for this transition. It keeps DAX > head/first-tail allocations on the normal vmemmap allocation path, while > preserving the existing page reference for reused DAX tail mappings. > > Signed-off-by: Muchun Song > --- > mm/sparse-vmemmap.c | 27 +++++++++++++++------------ > 1 file changed, 15 insertions(+), 12 deletions(-) > Acked-by: Qi Zheng Thanks, Qi