From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f180.google.com (mail-qt1-f180.google.com [209.85.160.180]) (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 0D906214812 for ; Sun, 22 Feb 2026 08:49:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771750173; cv=none; b=jmr9ExFos/X1+Mhktaq0N5u0NNzP/xxVaKHWsYSu5o4Rhi2ZqDcIzv45urgCaKDdfGn/tdBOzkdm4BOk1Dsl2u8EhTG+0JYugjR0eqrxettLof93VQdURyg5ydooxmd9zI1kJt75cEulc90KI4LcELPx2Fefur7pcN9S+n1L2z0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771750173; c=relaxed/simple; bh=fY2O2ukegsBDPZTxA7RgjpegM4UC0FoSjHYp6ZA4CME=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DckMVFBy3HXsWfCSdY6CL1Jw6iFKZwjL5p9XV6Fl/S7sGNPmjnsc577KA0Rat1a1GwB4jRCgXBv+FjmSqH2q7B95okUK162t4sXgIZUankG5hhrTjaEiqHKABPMde216E9TwcXsvEXRZZlpA80CIxp+G6f67OEUts/GzzPypJ0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net; spf=pass smtp.mailfrom=gourry.net; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b=NWrp7Hpc; arc=none smtp.client-ip=209.85.160.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gourry.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b="NWrp7Hpc" Received: by mail-qt1-f180.google.com with SMTP id d75a77b69052e-50334dd44d2so41382921cf.1 for ; Sun, 22 Feb 2026 00:49:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1771750170; x=1772354970; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=H0SIufGPxfCWQh/+gXEhZXOnJbmqG7niTtTuU93HVZQ=; b=NWrp7Hpcvpj9mkZbKrSc0+P2vmdVV65cXSZPjH+K2Xh+NIPAfvZv+vXn493H2JUVGK T+4IlHJrum2kMjxxdrho7R1HzdFdlbOHn52axMOxi+/aLi7rg1VbMIkGKaFgclTaAdq5 TkKro0I9ybhO7cvYf9JxuGiLVBVlTjJvkpfaffqxeAFD1gG+4Afr5agcoSt87ynUDttx gjsL7v1JhGmXCPFpqnmNth/ykpxkv+ePTr0ikdfRbs4URShBKADvBLf48Y9emXLhteyK GF+doUpTnEg6Wx8nQF0SFOhkJFKLVjwM50YLYqUQBOle4bItkN5G9xZdpmQZ6FA9pmmp xiPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771750170; x=1772354970; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=H0SIufGPxfCWQh/+gXEhZXOnJbmqG7niTtTuU93HVZQ=; b=MWS4O3/FnKf3p904OEODyOwUO/PLNUlT/452izM6kxdpfydB8soM6UX1j5dYZ/Arne CKAuapmv+jrvxLSFytnyFNLbOR5YF9J4EkDZzPKkdpnHyzxVZM/0mXvTLYL6pg9zRtqR A3ECatd/Vkogov8M4XcFpcNrGa078FSY+KfJXWcOdsIPiSDEgbBJAzP4Zx2RYoA8pCRe 7w7xppMEM8dgWYXYzlOIiQJmJ4nWnaSI+jqu2r5l7aCsdueJTs6cNU0BtbtDK89k0oAP KnX+gusBQnMpUZKee5Id5fn7wAvsHQ7J7davuRHHviw8Xqk9KkpPb6MP8iMoqBPiqzAX sQYw== X-Forwarded-Encrypted: i=1; AJvYcCUm1GAVKwfxMu+bzHH2z+T9We+CQr6vT5S1mvEft1nZJm4/c5sK6/6wqRH3AgQVbRRgGgEBAY17RewW3bcjnNbWT28=@vger.kernel.org X-Gm-Message-State: AOJu0Yzj2Zd1XeNUG+fcD0TSOOjcA69ErZUEeYEmg1VTTlbxsZmNTOXH TNC0+t/xtVQ/BFdfYddi90EKVCxzEMaCtGG73Hh3F7kirklLBJTARqBHFJFPjwez1HoNEqmkQLv aGbyw X-Gm-Gg: AZuq6aKukSqqbHlAT1kRLfSD+X5QBnG2cK1JTCNYFN7hZWdHIXxlCfh2bQtTOaVLTXD CBxAjkYviO66pewNJFcjkBKbBx0yH7dp78OS5mj6rmhCnqYRdYjJMkX2DeQ2FIhAbdmpH3w5ivE 1dpg40gth/oyXA7YeIT1xYqgc6AgY+KRiPgfCooHTCJ+239QsBhjgfn3XzWhXARlmMNV7LMktlX E216wHFYMLpLMiawo8Plxk//8v/9vC9xUy8WUtmB0FBURXGfnxJgc1LpU+ufANwv9ubQIke77Le sjKA12Gjia1kgZInl3Fhsn4SQwUIJyhAC6+rzubJrTx8vFpslKRUH/ShJySValTbFTRYougvSDq y8pnxFyyGOJrnT/3FofjHNEbm0hJBi2nDLmOYcldB/EMQzD9HfrFryoLv7J1wMkpE1VhsBzDs35 Yeyvt/DdhKQ7SGIagzcEdplOE8DWwR4zhPsXmHKh+YJl8SqgTOh683ojqlryq4c3mfuqLLwLwKQ gaWi0EPo9RAUPo= X-Received: by 2002:ac8:7d84:0:b0:506:8a2:b1ca with SMTP id d75a77b69052e-5070bcedb32mr65601961cf.73.1771750170035; Sun, 22 Feb 2026 00:49:30 -0800 (PST) Received: from gourry-fedora-PF4VCD3F.lan (pool-96-255-20-138.washdc.ftas.verizon.net. [96.255.20.138]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5070d53f0fcsm38640631cf.9.2026.02.22.00.49.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Feb 2026 00:49:29 -0800 (PST) From: Gregory Price To: lsf-pc@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, damon@lists.linux.dev, kernel-team@meta.com, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, longman@redhat.com, akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, osalvador@suse.de, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, jackmanb@google.com, sj@kernel.org, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, muchun.song@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, jannh@google.com, linmiaohe@huawei.com, nao.horiguchi@gmail.com, pfalcato@suse.de, rientjes@google.com, shakeel.butt@linux.dev, riel@surriel.com, harry.yoo@oracle.com, cl@gentwo.org, roman.gushchin@linux.dev, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, zhengqi.arch@bytedance.com, terry.bowman@amd.com Subject: [RFC PATCH v4 09/27] mm/khugepaged: skip private node folios when trying to collapse. Date: Sun, 22 Feb 2026 03:48:24 -0500 Message-ID: <20260222084842.1824063-10-gourry@gourry.net> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260222084842.1824063-1-gourry@gourry.net> References: <20260222084842.1824063-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A collapse operation allocates a new large folio and migrates the smaller folios into it. This is an issue for private nodes: 1. The private node service may not support migration 2. Collapse may promotes pages from the private node to a local node, which may result in an LRU inversion that defeats memory tiering. Handle this just like zone_device for now. It may be possible to support this later for some private node services that report explicit support for collapse (and migration). Signed-off-by: Gregory Price --- mm/khugepaged.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 97d1b2824386..36f6bc5da53c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -571,7 +572,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, goto out; } page = vm_normal_page(vma, addr, pteval); - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { + if (unlikely(!page) || unlikely(page_is_private_managed(page))) { result = SCAN_PAGE_NULL; goto out; } @@ -1323,7 +1324,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, } page = vm_normal_page(vma, addr, pteval); - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { + if (unlikely(!page) || unlikely(page_is_private_managed(page))) { result = SCAN_PAGE_NULL; goto out_unmap; } @@ -1575,7 +1576,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, } page = vm_normal_page(vma, addr, ptent); - if (WARN_ON_ONCE(page && is_zone_device_page(page))) + if (WARN_ON_ONCE(page && page_is_private_managed(page))) page = NULL; /* * Note that uprobe, debugger, or MAP_PRIVATE may change the -- 2.53.0