From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC89F1A6811 for ; Wed, 30 Sep 2026 01:26:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790731593; cv=none; b=JUf2ODbE8TdyuZnWXTFWKn977X9we75IMm/rgTD3o/kqKkpsi21Vf9p+OgGi1wcm01F0MPHujZyZyUyDSkPPKMcKcas943gyFh7VNhxTQ5kMSsdw3f4oH17oAMGbrD+CBSROaEub8aDpae0H0PyxPMMNK/JFa8jeBap3zS4iqwQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790731593; c=relaxed/simple; bh=IQRBqTSVWWALaW1mPWAac9TGAVH6p8Unuj/FQbT1y4Y=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=Wgn7JvexUlghwWRtKWE7p50UmVb0+uiBn3VoblM14sZaotyKPhQpANQAOJu+nK1zaBE1/G0FsLMhqnJithMx7GTN9KfTQM2MSwIUDG1GzltULBJAVRaef2T9CVFa4r+pv2PiPOcR04YfCrwnJ3PsG/XIsbp8qs0WME8PpRtOuJY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=WDOIv36O; arc=none smtp.client-ip=95.215.58.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="WDOIv36O" X-Envelope-To: linux-kernel@vger.kernel.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: linux-kernel@vger.kernel.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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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.