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 42D62CA5FA5 for ; Wed, 30 Sep 2026 01:26:59 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4hvcpT4fG5z2yYd; Wed, 30 Sep 2026 11:26:57 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2001:41d0:1004:224b::27" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1790731617; cv=none; b=bMLPYFLpAxgHm2J4hiJ9ylYAGKy+kkPJbiONWfLHBpdU3DDryufG9e+v7jO4C2Gusm2zqVfVA4KKpcRCYXw7wgNGjxNDNL4lcPPM2Y5507PJUxd1zyHF5/CWj3FM33rRpwk3UDYwIREDcbsR4j2kFq5y4wt+gL70cCIKCnJ7nogZTc//+KO6zt+J6fCBnCPwOc9mplatmYuKJ/27wjXwfpH/IBxAAyyNPVA1o/kOw2ClL8WMc4UbpTzfWaP5ul+iYB1LGwMHzRmuOV87pdEDzTLeMIGPnoTNivR9pfdQ1ED2OwUResdeyG2cFVKlawb59S1jpM/lD7iTAlJs2t5LHA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1790731617; c=relaxed/relaxed; bh=wCIueztMn6qtMBchJfx2etXVyYzxHf3iBKEIk5t2QtY=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=FLOGEMDvC99GSXduX+IWVvgXTw724J/09Is8GrfH+A6z8Yo5THXolIVCqsRXQ9Jzh4NHN6r1ROB/YNj165BIgZZyhusff148cQn4ufzWimMzMrsBIGTCbd0j614mdeeyQ324cBuTSIB3WXvXZFogDrNVMKjFlSLO28ZIe0kNE8Oa5Og8MBHIznzMDxuYSEqaegqlH1brPW+lsA8VEmAkw6trceIoY0XGDAIA9E1hBF20SGSkCI1bMJzWNtSnti+/2rYTKArnilwRNIfp1P2TXXj3ssWNX8Iey/MyGNUCJrGDqL4tMxEo2PF7J05vzNvDpbg7HA8y6+yYiVbuq+5GtQ== 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=WDOIv36O; dkim-atps=neutral; spf=pass (client-ip=2001:41d0:1004:224b::27; helo=mta0.migadu.com; envelope-from=muchun.song@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=WDOIv36O; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.dev (client-ip=2001:41d0:1004:224b::27; helo=mta0.migadu.com; envelope-from=muchun.song@linux.dev; receiver=lists.ozlabs.org) Received: from mta0.migadu.com (out-39.mta0.migadu.com [IPv6:2001:41d0:1004:224b::27]) (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 4hvcpQ35fbz2xSV for ; Wed, 30 Sep 2026 11:26:52 +1000 (AEST) X-Envelope-To: linuxppc-dev@lists.ozlabs.org DKIM-Signature: a=rsa-sha256; bh=IQRBqTSVWWALaW1mPWAac9TGAVH6p8Unuj/FQbT1y4Y=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790731588; v=1; x=1791336388; b=WDOIv36OO9lrltIsdKn1p/Dl5TCsZQOqtzhZ8Dh1WEGBKT/HjfCUvVmpfOfIXp1XoKlaFc5q Z3PVdE5TDYrfp7jP531Qv+J/ZtxbQfGTyP0S81oSGM/0+/SL5QyDC3zfxAlgMxdGtO07+QVXXD2 I9GSrh5b69ZqKxDrURbeoZXg= X-Envelope-To: linuxppc-dev@lists.ozlabs.org Received: by mta10.migadu.com with ESMTPS id c8969253a912e5f2; Wed, 30 Sep 2026 01:26:28 +0000 X-Mizu-Trace-ID: c8969253a912e5f2 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii 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 (Mac OS X Mail 16.0 \(3901.100.1.1.11\)) Subject: Re: [PATCH v3 0/6] mm: Unify device DAX and HugeTLB vmemmap population paths From: Muchun Song In-Reply-To: <20260929143214.9061bcf284369163192968d1@linux-foundation.org> Date: Wed, 30 Sep 2026 09:26:09 +0800 Cc: Muchun Song , Madhavan Srinivasan , Mike Rapoport , David Hildenbrand , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Qi Zheng , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260929053231.66085-1-songmuchun@bytedance.com> <20260929143214.9061bcf284369163192968d1@linux-foundation.org> To: Andrew Morton X-Mailer: Apple Mail (2.3901.100.1.1.11) > On Sep 30, 2026, at 05:32, Andrew Morton = wrote: >=20 > On Tue, 29 Sep 2026 13:32:25 +0800 Muchun Song = wrote: >=20 >> This v3 is based on mm-new commit 2ddb90ee544a, which contains v5 of >> "mm: Switch device DAX to section-based vmemmap optimization" [1]. >>=20 >> This series is split out from the earlier, larger series "mm: = Generalize >> HVO for HugeTLB and device DAX" [2]. While the parent series = generalizes >> vmemmap optimization across HugeTLB and device DAX, this subset = addresses >> a single, self-contained step: unifying their vmemmap population = paths. >>=20 >> After the preceding Device DAX conversion, both HugeTLB and Device = DAX >> describe optimized vmemmap mappings through memory-section metadata = and >> use per-zone shared tail vmemmap pages. The generic code, however, = still >> carries a Device DAX-specific population flag and compound-page = population >> path, along with arguments and helpers needed only by that path. >>=20 >> This series first removes VMEMMAP_POPULATE_DAX and moves selection = and >> reference handling for the shared tail page into the common vmemmap >> population path. It then removes the generic Device DAX-specific >> compound-page population path and routes section vmemmap population >> through vmemmap_populate(). The powerpc radix path continues to use = its >> architecture-specific compound-page population implementation for >> optimizable sections. >>=20 >> The remaining patches remove the unused ptpfn argument, open-code >> vmemmap_populate_address() now that no caller needs its returned PTE, = and >> add a warning for inconsistent zone initialization of shared tail = vmemmap >> pages. >>=20 >> This is the fourth smaller step toward the broader HVO = generalization. >> After this series, HugeTLB and Device DAX use the same population = model >> instead of parallel generic paths, while powerpc keeps its >> architecture-specific implementation. >=20 > afaict the whole series is "no functional changes intended". Apart > from [6/6]'s new WARN_ON. Yes. >=20 > And [3/6] is the one which could cause unintended fuctional changes! Understood. However, the resulting vmemmap layout is intended to remain unchanged. >=20 > Thanks. I'll queue it. Reluctantly. We're up to 688 MM patches this > cycle and it's time to stop. Thanks for taking it despite the load. Muchun, Thanks.